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?otorola inc., 1993 m68000 8-/16-/32-bit microprocessors user? manual motorola reserves the right to make changes without further notice to any products herein. motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. "typical" parameters can and do vary in different applications. all operating parameters, including "typicals" must be validated for each customer application by customer's technical experts. motorola does not convey any license under its patent rights nor the rights of others. motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the motorola product could create a situation where personal injury or death may occur. should buyer purchase or use motorola products for any such unintended or unauthorized application, buyer shall indemnify and hold motorola and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that motorola was negligent regarding the design or manufacture of the part. motorola and are registered trademarks of motorola, inc. motorola, inc. is an equal opportunity/affirmative action employer. motorola ninth edition
motorola m68000 user? manual vii table of contents paragraph page number title number section 1 overview 1.1 mc68000................................................................................................ ..... 1-1 1.2 mc68008................................................................................................ ..... 1-2 1.3 MC68010................................................................................................ ..... 1-2 1.4 mc68hc000................................................................................................ 1-2 1.5 mc68hc001................................................................................................ 1-3 1.6 mc68ec000 ................................................................................................ 1-3 section 2 introduction 2.1 programmer's model ................................................................................... 2-1 2.1.1 user's programmer's model .................................................................... 2-1 2.1.2 supervisor programmer's model ............................................................. 2-2 2.1.3 status register ........................................................................................ 2-3 2.2 data types and addressing modes ............................................................ 2-3 2.3 data organization in registers ................................................................... 2-5 2.3.1 data registers ......................................................................................... 2-5 2.3.2 address registers ................................................................................... 2-6 2.4 data organization in memory ..................................................................... 2-6 2.5 instruction set summary ............................................................................. 2-8 section 3 signal description 3.1 address bus ................................................................................................ 3-3 3.2 data bus...................................................................................................... 3-4 3.3 asynchronous bus control.......................................................................... 3-4 3.4 bus arbitration control ................................................................................ 3-5 3.5 interrupt control .......................................................................................... 3-6 3.6 system control............................................................................................ 3-7 3.7 m6800 peripheral control ........................................................................... 3-8 3.8 processor function codes .......................................................................... 3-8 3.9 clock ........................................................................................................... 3-9 3.10 power supply .............................................................................................. 3-9 3.11 signal summary ......................................................................................... 3-10
viii m68000 user? manual motorola table of contents (continued) paragraph page number title number section 4 8-bit bus operations 4.1 data transfer operations............................................................................. 4-1 4.1.1 read operations ...................................................................................... 4-1 4.1.2 write cycle ............................................................................................... 4-3 4.1.3 read-modify-write cycle.......................................................................... 4-5 4.2 other bus operations............................................................................... 4-8 section 5 16-bit bus operations 5.1 data transfer operations............................................................................ 5-1 5.1.1 read operations ..................................................................................... 5-1 5.1.2 write cycle .............................................................................................. 5-4 5.1.3 read-modify-write cycle......................................................................... 5-7 5.1.4 cpu space cycle.................................................................................... 5-9 5.2 bus arbitration .......................................................................................... 5-11 5.2.1 requesting the bus .............................................................................. 5-14 5.2.2 receiving the bus grant ...................................................................... 5-15 5.2.3 acknowledgment of mastership (3-wire arbitration only)..................... 5-15 5.3 bus arbitration control .............................................................................. 5-15 5.4 bus error and halt operation .................................................................... 5-23 5.4.1 bus error operation .............................................................................. 5-24 5.4.2 retrying the bus cycle......................................................................... 5-26 5.4.3 halt operation ....................................................................................... 5-27 5.4.4 double bus fault ................................................................................... 5-28 5.5 reset operation ........................................................................................ 5-29 5.6 the relationship of dtack, berr , and halt ......................................... 5-30 5.7 asynchronous operation .......................................................................... 5-32 5.8 synchronous operation ............................................................................ 5-35 section 6 exception processing 6.1 privilege modes............................................................................................ 6-1 6.1.1 supervisor mode ...................................................................................... 6-2 6.1.2 user mode ................................................................................................ 6-2 6.1.3 privilege mode changes .......................................................................... 6-2 6.1.4 reference classification........................................................................... 6-3 6.2 exception processing................................................................................... 6-4 6.2.1 exception vectors .................................................................................... 6-4 6.2.2 kinds of exceptions ................................................................................. 6-5 6.2.3 multiple exceptions................................................................................... 6-8
motorola m68000 user? manual ix table of contents (continued) paragraph page number title number section 6 exception processing 6.2.4 exception stack frames.......................................................................... 6-9 6.2.5 exception processing sequence ............................................................ 6-11 6.3 processing of specific exceptions ............................................................. 6-11 6.3.1 reset ...................................................................................................... 6-11 6.3.2 interrupts ................................................................................................ 6-12 6.3.3 uninitialized interrupt .............................................................................. 6-13 6.3.4 spurious interrupt ................................................................................... 6-13 6.3.5 instruction traps ..................................................................................... 6-13 6.3.6 illegal and unimplemented instructions .................................................. 6-14 6.3.7 privilege violations ................................................................................. 6-15 6.3.8 tracing .................................................................................................... 6-15 6.3.9 bus errors ............................................................................................... 6-16 6.3.9.1 bus error ............................................................................................. 6-16 6.3.9.2 bus error (MC68010) .......................................................................... 6-17 6.3.10 address error ......................................................................................... 6-19 6.4 return from exception (MC68010) ........................................................... 6-20 section 7 8-bit instruction timing 7.1 operand effective address calculation times............................................ 7-1 7.2 move instruction execution times .............................................................. 7-2 7.3 standard instruction execution times......................................................... 7-3 7.4 immediate instruction execution times ...................................................... 7-4 7.5 single operand instruction execution times .............................................. 7-5 7.6 shift/rotate instruction execution times .................................................... 7-6 7.7 bit manipulation instruction execution times ............................................. 7-7 7.8 conditional instruction execution times ..................................................... 7-7 7.9 jmp, jsr, lea, pea, and movem instruction execution times............... 7-8 7.10 multiprecision instruction execution times ................................................. 7-8 7.11 miscellaneous instruction execution times ................................................ 7-9 7.12 exception processing instruction execution times ................................... 7-10
x m68000 user? manual motorola table of contents (continued) paragraph page number title number section 8 16-bit instruction timing 8.1 operand effective address calculation times ........................................... 8-1 8.2 move instruction execution times .............................................................. 8-2 8.3 standard instruction execution times ........................................................ 8-3 8.4 immediate instruction execution times ...................................................... 8-4 8.5 single operand instruction execution times .............................................. 8-5 8.6 shift/rotate instruction execution times .................................................... 8-6 8.7 bit manipulation instruction execution times ............................................. 8-7 8.8 conditional instruction execution times ..................................................... 8-7 8.9 jmp, jsr, lea, pea, and movem instruction execution times .............. 8-8 8.10 multiprecision instruction execution times ................................................. 8-8 8.11 miscellaneous instruction execution times ................................................ 8-9 8.12 exception processing instruction execution times .................................. 8-10 section 9 MC68010 instruction timing 9.1 operand effective address calculation times ........................................... 9-2 9.2 move instruction execution times .............................................................. 9-2 9.3 standard instruction execution times ........................................................ 9-4 9.4 immediate instruction execution times ...................................................... 9-6 9.5 single operand instruction execution times .............................................. 9-6 9.6 shift/rotate instruction execution times .................................................... 9-8 9.7 bit manipulation instruction execution times ............................................. 9-9 9.8 conditional instruction execution times ..................................................... 9-9 9.9 jmp, jsr, lea, pea, and movem instruction execution times ............ 9-10 9.10 multiprecision instruction execution times ............................................... 9-11 9.11 miscellaneous instruction execution times .............................................. 9-11 9.12 exception processing instruction execution times .................................. 9-13 section 10 electrical and thermal characteristics 10.1 maximum ratings ..................................................................................... 10-1 10.2 thermal characteristics ............................................................................ 10-1 10.3 power considerations ............................................................................... 10-2 10.4 cmos considerations .............................................................................. 10-4 10.5 ac electrical specifications definitions..................................................... 10-5 10.6 mc68000/68008/68010 dc electrical characteristics .............................. 10-7 10.7 dc electrical characteristics .................................................................... 10-8 10.8 ac electrical specifications?lock timing .............................................. 10-8
motorola m68000 user? manual xi table of contents (continued) paragraph page number title number section 10 electrical and thermal characteristics 10.9 mc68008 ac electrical specifications?lock timing ............................. 10-9 10.10 ac electrical specifications?ead and write cycles ............................ 10-10 10.11 ac electrical specifications?c68000 to m6800 peripheral............... 10-15 10.12 ac electrical specifications?us arbitration ......................................... 10-17 10.13 mc68ec000 dc electrical spec ifications.............................................. 10-23 10.14 mc68ec000 ac electrical specifications?ead and write .................. 10-24 10.15 mc68ec000 ac electrical specifications?us arbitration .................... 10-28 section 11 ordering information and mechanical data 11.1 pin assignments........................................................................................ 11-1 11.2 package dimensions ................................................................................ 11-7 appendix a MC68010 loop mode operation appendix b m6800 peripheral interface b.1 data transfer operation............................................................................. b-1 b.2 interrupt interface operation ...................................................................... b-4
xii m68000 user? manual motorola list of illustrations figure page number title number 2-1 user programmer's model ................................................................................... 2-2 2-2 supervisor programmer's model supplement ..................................................... 2-2 2-3 supervisor programmer's model supplement (MC68010) .................................. 2-3 2-4 status register .................................................................................................... 2-3 2-5 word organization in memory ............................................................................. 2-6 2-6 data organization in memory .............................................................................. 2-7 2-7 memory data organization (mc68008) ............................................................... 2-3 3-1 input and output signals (mc68000, mc68hc000, MC68010) .......................... 3-1 3-2 input and output signals ( mc68hc001) ............................................................ 3-2 3-3 input and output signals (mc68ec000) ............................................................. 3-2 3-4 input and output signals (mc68008 48-pin version) .......................................... 3-3 3-5 input and output signals (mc68008 52-pin version) .......................................... 3-3 4-1 byte read-cycle flowchart.................................................................................. 4-2 4-2 read and write-cycle timing diagram................................................................ 4-2 4-3 byte write-cycle flowchart .................................................................................. 4-4 4-4 write-cycle timing diagram ................................................................................ 4-4 4-5 read-modify-write cycle flowchart .................................................................... 4-6 4-6 read-modify-write cycle timing diagram........................................................... 4-7 5-1 word read-cycle flowchart ................................................................................ 5-2 5-2 byte read-cycle flowchart.................................................................................. 5-2 5-3 read and write-cycle timing diagram................................................................ 5-3 5-4 word and byte read-cycle timing diagram ....................................................... 5-3 5-5 word write-cycle flowchart ................................................................................ 5-5 5-6 byte write-cycle flowchart .................................................................................. 5-5 5-7 word and byte write-cycle timing diagram ....................................................... 5-6 5-8 read-modify-write cycle flowchart .................................................................... 5-7 5-9 read-modify-write cycle timing diagram........................................................... 5-8 5-10 cpu space address encoding ............................................................................ 5-9 5-11 interrupt acknowledge cycle timing diagram ................................................... 5-10 5-12 breakpoint acknowledge cycle timing diagram ............................................... 5-11 5-13 3-wire bus arbitration flowchart (na to 48-pin mc68008 and mc68ec000 ........................................................ 5-12 5-14 2-wire bus arbitration cycle flowchart ............................................................. 5-13
motorola m68000 user? manual xiii list of illustrations (continued) figure page number title number 5-15 3-wire bus arbitration timing diagram (na to 48-pin mc68008 and mc68ec000 ........................................................ 5-13 5-16 2-wire bus arbitration timing diagram.............................................................. 5-14 5-17 external asynchronous signal synchronization ................................................. 5-16 5-18 bus arbitration unit state diagrams................................................................... 5-17 5-19 3-wire bus arbitration timing diagram?rocessor active ............................... 5-18 5-20 3-wire bus arbitration timing diagram?us active ......................................... 5-19 5-21 3-wire bus arbitration timing diagram?pecial case ................................ ..... 5-20 5-22 2-wire bus arbitration timing diagram?rocessor active ............................... 5-21 5-23 2-wire bus arbitration timing diagram?us active ......................................... 5-22 5-24 2-wire bus arbitration timing diagram?pecial case ................................ ..... 5-23 5-25 bus error timing diagram .................................................................................. 5-24 5-26 delayed bus error timing diagram (MC68010)................................................. 5-25 5-27 retry bus cycle timing diagram ....................................................................... 5-26 5-28 delayed retry bus cycle timing diagram ......................................................... 5-27 5-29 halt operation timing diagram.......................................................................... 5-28 5-30 reset operation timing diagram....................................................................... 5-29 5-31 fully asynchronous read cycle ........................................................................ 5-32 5-32 fully asynchronous write cycle......................................................................... 5-33 5-33 pseudo-asynchronous read cycle ................................................................... 5-34 5-34 pseudo-asynchronous write cycle.................................................................... 5-35 5-35 synchronous read cycle................................................................................... 5-37 5-36 synchronous write cycle ................................................................................... 5-38 5-37 input synchronizers ........................................................................................... 5-38 6-1 exception vector format...................................................................................... 6-4 6-2 peripheral vector number format ....................................................................... 6-5 6-3 address translated from 8-bit vector number ................................................... 6-5 6-4 exception vector address calculation (MC68010) .............................................. 6-5 6-5 group 1 and 2 exception stack frame .............................................................. 6-10 6-6 MC68010 stack frame ...................................................................................... 6-10 6-7 supervisor stack order for bus or address error exception ............................. 6-17 6-8 exception stack order (bus and address error) ............................................... 6-18 6-9 special status word format .............................................................................. 6-19 10-1 mc68000 power dissipation (p d ) vs ambient temperature (t a ) ..................... 10-3 10-2 drive levels and test points for ac specifications ........................................... 10-6 10-3 clock input timing diagram ............................................................................... 10-9 10-4 read cycle timing diagram ............................................................................ 10-13 10-5 write cycle timing diagram............................................................................. 10-14 10-6 mc68000 to m6800 peripheral timing diagram (best case) .......................... 10-16
xiv m68000 user? manual motorola list of illustrations (concluded) figure page number title number 10-7 bus arbitration timing...................................................................................... 10-18 10-8 bus arbitration timing...................................................................................... 10-19 10-9 bus arbitration timing?dle bus case ............................................................ 10-20 10-10 bus arbitration timing?ctive bus case........................................................ 10-21 10-11 bus arbitration timing?ultiple bus request ................................................ 10-22 10-12 mc68ec000 read cycle timing diagram ...................................................... 10-26 10-13 mc68ec000 write cycle timing diagram....................................................... 10-27 10-14 mc68ec000 bus arbitration timing diagram ................................................. 10-29 11-1 64-pin dual in line ............................................................................................ 11-2 11-2 68-lead pin grid array ...................................................................................... 11-3 11-3 68-lead quad pack ........................................................................................... 11-4 11-4 52-lead quad pack ........................................................................................... 11-5 11-5 48-pin dual in line ............................................................................................ 11-6 11-6 64-lead quad flat pack .................................................................................... 11-7 11-7 case 740-03? suffix ....................................................................................... 11-8 11-8 case 767-02? suffix ...................................................................................... 11-9 11-9 case 746-01?c suffix .................................................................................. 11-10 11-10 case ?suffix ...................................................................................................... 11- 11-11 case 765a-05?c suffix ............................................................................... 11-12 11-12 case 778-02?n suffix .................................................................................. 11-13 11-13 case 779-02?n suffix .................................................................................. 11-14 11-14 case 847-01?c suffix .................................................................................. 11-15 11-15 case 840b-01?u suffix................................................................................ 11-16 a-1 dbcc loop mode program example................................................................... a-1 b-1 m6800 data transfer flowchart ......................................................................... b-1 b-2 example external vma circuit ............................................................................ b-2 b-3 external vma timing .......................................................................................... b-2 b-4 m6800 peripheral timing?est case................................................................ b-3 b-5 m6800 peripheral timing?orst case ............................................................. b-3 b-6 autovector operation timing diagram................................................................ b-5
motorola m68000 user? manual xv list of tables table page number title number 2-1 data addressing modes ....................................................................................... 2-4 2-2 instruction set summary .................................................................................... 2-11 3-1 data strobe control of data bus.......................................................................... 3-5 3-2 data strobe control of data bus (mc68008)....................................................... 3-5 3-3 function code output .......................................................................................... 3-9 3-4 signal summary ................................................................................................. 3-10 5-1 dtack, berr , and halt assertion results ..................................................... 5-31 6-1 reference classification....................................................................................... 6-3 6-2 exception vector assignment .............................................................................. 6-7 6-3 exception grouping and priority........................................................................... 6-9 6-4 MC68010 format code...................................................................................... 6-11 7-1 effective address calculation times.................................................................... 7-2 7-2 move byte instruction execution times ............................................................... 7-2 7-3 move word instruction execution times.............................................................. 7-3 7-4 move long instruction execution times .............................................................. 7-3 7-5 standard instruction execution times.................................................................. 7-4 7-6 immediate instruction execution times ............................................................... 7-5 7-7 single operand instruction execution times ....................................................... 7-6 7-8 shift/rotate instruction execution times ............................................................. 7-6 7-9 bit manipulation instruction execution times ...................................................... 7-7 7-10 conditional instruction execution times .............................................................. 7-7 7-11 jmp, jsr, lea, pea, and movem instruction execution times........................ 7-8 7-12 multiprecision instruction execution times .......................................................... 7-9 7-13 miscellaneous instruction execution times ....................................................... 7-10 7-14 move peripheral instruction execution times .................................................... 7-10 7-15 exception processing instruction execution times ........................................... 7-11 8-1 effective address calculation times.................................................................... 8-2 8-2 move byte instruction execution times ............................................................... 8-2 8-3 move word instruction execution times.............................................................. 8-3 8-4 move long instruction execution times .............................................................. 8-3
xvi m68000 user? manual motorola list of tables (concluded) table page number title number 8-5 standard instruction execution times ................................................................. 8-4 8-6 immediate instruction execution times ............................................................... 8-5 8-7 single operand instruction execution times ....................................................... 8-6 8-8 shift/rotate instruction execution times ............................................................. 8-6 8-9 bit manipulation instruction execution times ...................................................... 8-7 8-10 conditional instruction execution times .............................................................. 8-7 8-11 jmp, jsr, lea, pea, and movem instruction execution times ....................... 8-8 8-12 multiprecision instruction execution times .......................................................... 8-9 8-13 miscellaneous instruction execution times ....................................................... 8-10 8-14 move peripheral instruction execution times.................................................... 8-10 8-15 exception processing instruction execution times ........................................... 8-11 9-1 effective address calculation times ................................................................... 9-2 9-2 move byte and word instruction execution times .............................................. 9-3 9-3 move byte and word instruction loop mode execution times ........................... 9-3 9-4 move long instruction execution times .............................................................. 9-4 9-5 move long instruction loop mode execution times ........................................... 9-4 9-6 standard instruction execution times ................................................................. 9-5 9-7 standard instruction loop mode execution times .............................................. 9-5 9-8 immediate instruction execution times ............................................................... 9-6 9-9 single operand instruction execution times ....................................................... 9-7 9-10 clear instruction execution times ....................................................................... 9-7 9-11 single operand instruction loop mode execution times .................................... 9-8 9-12 shift/rotate instruction execution times ............................................................. 9-8 9-13 shift/rotate instruction loop mode execution times .......................................... 9-9 9-14 bit manipulation instruction execution times ...................................................... 9-9 9-15 conditional instruction execution times ............................................................ 9-10 9-16 jmp, jsr, lea, pea, and movem instruction execution times ..................... 9-10 9-17 multiprecision instruction execution times ........................................................ 9-11 9-18 miscellaneous instruction execution times ....................................................... 9-12 9-19 exception processing instruction execution times ........................................... 9-13 10-1 power dissipation and junction temperature vs temperature ( q j c = q j a ) ........................................................................................................ 10-4 10-2 power dissipation and junction temperature vs temperature ( q j c = q j c ) ........................................................................................................ 10-4 a-1 MC68010 loop mode instructions ...................................................................... a-3
motorola m68000 8-/16-/32-bit microprocessors user? manual 1- 1 section 1 overview this manual includes hardware details and programming information for the mc68000, the mc68hc000, the mc68hc001, the mc68008, the MC68010, and the mc68ec000. for ease of reading, the name m68000 mpus will be used when referring to all processors. refer to m68000pm/ad, m68000 programmer's reference manual , for detailed information on the mc68000 instruction set. the six microprocessors are very similar. they all contain the following features ?16 32-bit data and address registers ?16-mbyte direct addressing range ?program counter ?6 powerful instruction types ?operations on five main data types ?memory-mapped input/output (i/o) ?14 addressing modes the following processors contain additional features: ?MC68010 ?irtual memory/machine support ?igh-performance looping instructions ?mc68hc001/mc68ec000 ?tatically selectable 8- or 16-bit data bus ?mc68hc000/mc68ec000/mc68hc001 ?ow-power all the processors are basically the same with the exception of the mc68008. the mc68008 differs from the others in that the data bus size is eight bits, and the address range is smaller. the MC68010 has a few additional instructions and instructions that operate differently than the corresponding instructions of the other devices.
1- 2 m68000 8-/16-/32-bit microprocessors user? manual motorola 1.1 mc68000 the mc68000 is the first implementation of the m68000 16/-32 bit microprocessor architecture. the mc68000 has a 16-bit data bus and 24-bit address bus while the full architecture provides for 32-bit address and data buses. it is completely code-compatible with the mc68008 8-bit data bus implementation of the m68000 and is upward code compatible with the MC68010 virtual extensions and the mc68020 32-bit implementation of the architecture. any user-mode programs using the mc68000 instruction set will run unchanged on the mc68008, MC68010, mc68020, mc68030, and mc68040. this is possible because the user programming model is identical for all processors and the instruction sets are proper subsets of the complete architecture. 1.2 mc68008 the mc68008 is a member of the m68000 family of advanced microprocessors. this device allows the design of cost-effective systems using 8-bit data buses while providing the benefits of a 32-bit microprocessor architecture. the performance of the mc68008 is greater than any 8-bit microprocessor and superior to several 16-bit microprocessors. the mc68008 is available as a 48-pin dual-in-line package (plastic or ceramic) and 52-pin plastic leaded chip carrier. the additional four pins of the 52-pin package allow for additional signals: a20, a21, bgack , and ipl2 . the 48-pin version supports a 20-bit address that provides a 1-mbyte address space; the 52-pin version supports a 22-bit address that extends the address space to 4 mbytes. the 48-pin mc68008 contains a simple two-wire arbitration circuit; the 52-pin mc68008 contains a full three-wire mc68000 bus arbitration control. both versions are designed to work with daisy-chained networks, priority encoded networks, or a combination of these techniques. a system implementation based on an 8-bit data bus reduces system cost in comparison to 16-bit systems due to a more effective use of components and byte-wide memories and peripherals. in addition, the nonmultiplexed address and data buses eliminate the need for external demultiplexers, further simplifying the system. the large nonsegmented linear address space of the mc68008 allows large modular programs to be developed and executed efficiently. a large linear address space allows program segment sizes to be determined by the application rather than forcing the designer to adopt an arbitrary segment size without regard to the application's individual requirements. 1.3 MC68010 the MC68010 utilizes vlsi technology and is a fully implemented 16-bit microprocessor with 32-bit registers, a rich basic instruction set, and versatile addressing modes. the vector base register (vbr) allows the vector table to be dynamically relocated
motorola m68000 8-/16-/32-bit microprocessors user? manual 1- 3 1.4 mc68hc000 the primary benefit of the mc68hc000 is reduced power consumption. the device dissipates an order of magnitude less power than the hmos mc68000. the mc68hc000 is an implementation of the m68000 16/-32 bit microprocessor architecture. the mc68hc000 has a 16-bit data bus implementation of the mc68000 and is upward code-compatible with the MC68010 virtual extensions and the mc68020 32-bit implementation of the architecture. 1.5 mc68hc001 the mc68hc001 provides a functional extension to the mc68hc000 hcmos 16-/32-bit microprocessor with the addition of statically selectable 8- or 16-bit data bus operation. the mc68hc001 is object-code compatible with the mc68hc000, and code written for the mc68hc001 can be migrated without modification to any member of the m68000 family. 1.6 mc68ec000 the mc68ec000 is an economical high-performance embedded controller designed to suit the needs of the cost-sensitive embedded controller market. the hcmos mc68ec000 has an internal 32-bit architecture that is supported by a statically selectable 8- or 16-bit data bus. this architecture provides a fast and efficient processing device that can satisfy the requirements of sophisticated applications based on high-level languages. the mc68ec000 is object-code compatible with the mc68000, and code written for the mc68ec000 can be migrated without modification to any member of the m68000 family. the mc68ec000 brings the performance level of the m68000 family to cost levels previously associated with 8-bit microprocessors. the mc68ec000 benefits from the rich m68000 instruction set and its related high code density with low memory bandwidth requirements.
motorola m68000 8-/16-/32-bit microprocessor user? manual 2-1 section 2 introduction the section provide a brief introduction to the m68000 microprocessors (mpus). detailed information on the programming model, data types, addressing modes, data organization and instruction set can be found in m68000pm/ad, m68000 programmer's reference manual . all the processors are identical from the programmer's viewpoint, except that the mc68000 can directly access 16 mbytes (24-bit address) and the mc68008 can directly access 1 mbyte (20-bit address on 48-pin version or 22-bit address on 52-pin version). the MC68010, which also uses a 24-bit address, has much in common with the other devices; however, it supports additional instructions and registers and provides full virtual machine/memory capability. unless noted, all information pertains to all the m68000 mpus. 2.1 programmer's model all the microprocessors executes instructions in one of two modes?ser mode or supervisor mode. the user mode provides the execution environment for the majority of application programs. the supervisor mode, which allows some additional instructions and privileges, is used by the operating system and other system software. 2.1.1 user' programmer's model the user programmer's model (see figure 2-1) is common to all m68000 mpus. the user programmer's model, contains 16, 32-bit, general-purpose registers (d0?7, a0 a7), a 32-bit program counter, and an 8-bit condition code register. the first eight registers (d0?7) are used as data registers for byte (8-bit), word (16-bit), and long-word (32-bit) operations. the second set of seven registers (a0?6) and the user stack pointer (usp) can be used as software stack pointers and base address registers. in addition, the address registers can be used for word and long-word operations. all of the 16 registers can be used as index registers.
2-2 m68000 8-/16-/32-bit microprocessor user? manual motorola 31 16 15 8 7 0 31 16 15 0 d0 d1 d2 d3 d4 d5 d6 d7 a1 a2 a3 a4 a5 a6 a0 a7 (usp) pointer pc ccr status register program counter user stack seven address registers eight data registers 31 70 0 figure 2-1. user programmer's model (mc68000/mc68hc000/mc68008/MC68010) 2.1.2 supervisor programmer's model the supervisor programmer's model consists of supplementary registers used in the supervisor mode. the m68000 mpus contain identical supervisor mode register resources, which are shown in figure 2-2, including the status register (high-order byte) and the supervisor stack pointer (ssp/a7'). supervisor stack pointer 31 16 15 0 15 8 7 0 status register a7' (ssp) sr ccr figure 2-2. supervisor programmer's model supplement the supervisor programmer's model supplement of the MC68010 is shown in figure 2- 3. in addition to the supervisor stack pointer and status register, it includes the vector base register (vrb) and the alternate function code registers (afc).the vbr is used to determine the location of the exception vector table in memory to support multiple vector
motorola m68000 8-/16-/32-bit microprocessor user? manual 2-3 tables. the sfc and dfc registers allow the supervisor to access user data space or emulate cpu space cycles. 31 16 15 0 15 8 7 0 a7' (ssp) supervisor stack pointer ccr sr status register 31 0 vbr vector base register 20 sfc dfc alternate function code registers figure 2-3. supervisor programmer's model supplement (MC68010) 2.1.3 status register the status register (sr),contains the interrupt mask (eight levels available) and the following condition codes: overflow (v), zero (z), negative (n), carry (c), and extend (x). additional status bits indicate that the processor is in the trace (t) mode and/or in the supervisor (s) state (see figure 2-4). bits 5, 6, 7, 11, 12, and 14 are undefined and reserved for future expansion t s iii xnzvc 210 15 13 10 8 4 0 trace mode supervisor state interrupt mask extend negative zero overflow carry condition codes system byte user byte figure 2-4. status register 2.2 data types and addressing modes the five basic data types supported are as follows: 1. bits 2. binary-coded-decimal (bcd) digits (4 bits) 3. bytes (8 bits) 4. words (16 bits) 5. long words (32 bits)
2-4 m68000 8-/16-/32-bit microprocessor user? manual motorola in addition, operations on other data types, such as memory addresses, status word data, etc., are provided in the instruction set. the 14 flexible addressing modes, shown in table 2-1, include six basic types: 1. register direct 2. register indirect 3. absolute 4. immediate 5. program counter relative 6. implied the register indirect addressing modes provide postincrementing, predecrementing, offsetting, and indexing capabilities. the program counter relative mode also supports indexing and offsetting. for detail information on addressing modes refer to m68000pm/ad, m68000 programmer reference manual .
motorola m68000 8-/16-/32-bit microprocessor user? manual 2-5 table 2-1. data addressing modes mode generation syntax register direct addressing data register direct address register direct ea=dn ea=an dn an absolute data addressing absolute short absolute long ea = (next word) ea = (next two words) (xxx).w (xxx).l program counter relative addressing relative with offset relative with index and offset ea = (pc)+d 16 ea = (pc)+d 8 (d 16 ,pc) (d 8 ,pc,xn) register indirect addressing register indirect postincrement register indirect predecrement register indirect register indirect with offset indexed register indirect with offset ea = (an) ea = (an), an ? an+n an ? an?, ea=(an) ea = (an)+d 16 ea = (an)+(xn)+d 8 (an) (an)+ -(an) (d 16 ,an) (d 8 ,an,xn) immediate data addressing immediate quick immediate data = next word(s) inherent data # implied addressing 1 implied register ea = sr, usp, ssp, pc, vbr, sfc, dfc sr,usp,ssp,pc, vbr, sfc,dfc notes: 1. the vbr, sfc, and dfc apply to the MC68010 only ea = effective address dn = data register an = address register ( ) = contents of pc = program counter d 8 = 8-bit offset (displacement) d 16 = 16-bit offset (displacement) n = 1 for byte, 2 for word, and 4 for long word. if an is the stack pointer and the operand size is byte, n = 2 to keep the stack pointer on a word boundary. ? = replaces xn = address or data register used as index register sr = status register usp = user stack pointer ssp = supervisor stack pointer cp = program counter vbr = vector base register 2.3 data organization in registers the eight data registers support data operands of 1, 8, 16, or 32 bits. the seven address registers and the active stack pointer support address operands of 32 bits. 2.3.1 data registers each data register is 32 bits wide. byte operands occupy the low-order 8 bits, word operands the low-order 16 bits, and long-word operands, the entire 32 bits. the least significant bit is addressed as bit zero; the most significant bit is addressed as bit 31.
2-6 m68000 8-/16-/32-bit microprocessor user? manual motorola when a data register is used as either a source or a destination operand, only the appropriate low-order portion is changed; the remaining high-order portion is neither used nor changed. 2.3.2 address registers each address register (and the stack pointer) is 32 bits wide and holds a full, 32-bit address. address registers do not support byte-sized operands. therefore, when an address register is used as a source operand, either the low-order word or the entire long-word operand is used, depending upon the operation size. when an address register is used as the destination operand, the entire register is affected, regardless of the operation size. if the operation size is word, operands are sign-extended to 32 bits before the operation is performed. 2.4 data organization in memory bytes are individually addressable. as shown in figure 2-5, the high-order byte of a word has the same address as the word. the low-order byte has an odd address, one count higher. instructions and multibyte data are accessed only on word (even byte) boundaries. if a long-word operand is located at address n (n even), then the second word of that operand is located at address n+2. byte 000000 byte 000001 word 0 word 1 byte 000003 byte 000002 byte fffffe byte fffffe word 7fffff 1514131211109876543210 address $000000 $000002 $fffffe figure 2-5. word organization in memory the data types supported by the m68000 mpus are bit data, integer data of 8, 16, and 32 bits, 32-bit addresses, and binary-coded-decimal data. each data type is stored in memory as shown in figure 2-6. the numbers indicate the order of accessing the data from the processor. for the mc68008 with its 8-bit bus, the appearance of data in memory is identical to the all the m68000 mpus. the organization of data in the memory of the mc68008 is shown in figure 2-7.
motorola m68000 8-/16-/32-bit microprocessor user? manual 2-7 1514131211109876 543210 msb byte 0 byte 2 byte 1 byte 3 lsb integer data 1 byte = 8 bits 1 word = 16 bits bit data 1 byte = 8 bits 76 543210 151413121110 9876 543210 word 0 word 1 word 2 lsb msb even byte odd byte 1 long word = 32 bits long word 0 long word 1 long word 2 low order high order lsb msb 1514131211109876 543210 76 54321 0 76 54321 0 address 1 address 2 low order high order lsb msb 151413121110 9876 543210 addresses 1 address = 32 bits msb = most significant bit lsb = least significant bit address 0 decimal data 2 binary-coded-decimal digits = 1 byte 151413121110 9876 543210 msd bcd 0 bcd 4 bcd 1 bcd 5 bcd 2 bcd 6 bcd 3 bcd 7 msd = most significant digit lsd = least significant digit lsd figure 2-6. data organization in memory
2-8 m68000 8-/16-/32-bit microprocessor user? manual motorola bit data 1 byte = 8 bits 76543210 integer data 1 byte = 8 bits byte 0 byte 1 byte 2 byte 3 higher addresses 76 543210 lower addresses lower addresses byte 0 byte 1 byte 1 (ms byte) (ls byte) (ms byte) (ls byte) word 0 word 1 higher addresses 1 word = 2 bytes = 16 bits byte 0 1 long word = 2 words = 4 bytes = 32 bits byte 0 byte 1 byte 2 byte 3 byte 0 byte 1 byte 2 byte 3 high-order word low-order word long word 1 long word 0 high-order word low-order word lower addresses higher addresses figure 2-7. memory data organization of the mc68008 2.5 instruction set summary table 2-2 provides an alphabetized listing of the m68000 instruction set listed by opcode, operation, and syntax. in the syntax descriptions, the left operand is the source operand, and the right operand is the destination operand. the following list contains the notations used in table 2-2.
motorola m68000 8-/16-/32-bit microprocessor user? manual 2-9 notation for operands: pc program counter sr status register v overflow condition code immediate data immediate data from the instruction source source contents destination destination contents vector location of exception vector +inf positive infinity ?nf negative infinity operand data format: byte (b), word (w), long (l), single (s), double (d), extended (x), or packed (p). fpm one of eight floating-point data registers (always specifies the source register) fpn one of eight floating-point data registers (always specifies the destination register) notation for subfields and qualifiers: of selects a single bit of the operand {offset:width} selects a bit field () the contents of the referenced location 10 the operand is bina ry-coded decimal, operations are performed in decimal (

) the register indirect operator ?

) indicates that the operand register points to the memory (

)+ location of the instruction operand?he optional mode qualifiers are ? +, (d), and (d, ix) #xxx or # immediate data that follows the instruction word(s) notations for operations that have two operands, written , where is one of the following: ? the source operand is moved to the destination operand ? the two operands are exchanged + the operands are added the destination operand is subtracted from the source operand the operands are multiplied ? the source operand is divided by the destination operand < relational test, true if source operand is less than destination operand > relational test, true if source operand is greater than destination operand v logical or ? logical exclusive or l logical and
2-10 m68000 8-/16-/32-bit microprocessor user? manual motorola shifted by, rotated by the source operand is shifted or rotated by the number of positions specified by the second operand notation for single-operand operations: ~ the operand is logically complemented sign-extended the operand is sign-extended, all bits of the upper portion are made equal to the high-order bit of the lower portion tested the operand is compared to zero and the condition codes are set appropriately notation for other operations: trap equivalent to format/offset word ? (ssp); ssp? ? ssp; pc ? (ssp); ssp? ? ssp; sr ? (ssp); ssp? ? ssp; (vector) ? pc stop enter the stopped state, waiting for interrupts if then the condition is tested. if true, the operations after "then" else are performed. if the condition is false and the optional "else" clause is present, the operations after "else" are performed. if the condition is false and else is omitted, the instruction performs no operation. refer to the bcc instruction description as an example.
motorola m68000 8-/16-/32-bit microprocessor user? manual 2-11 table 2-2. instruction set summary (sheet 1 of 4) opcode operation syntax abcd source 10 + destination 10 + x ? destination abcd dy,dx abcd ?ay), ?ax) add source + destination ? destination add ,dn add dn, adda source + destination ? destination adda ,an addi immediate data + destination ? destination addi # , addq immediate data + destination ? destination addq # , addx source + destination + x ? destination addx dy, dx addx ?ay), ?ax) and source l destination ? destination and ,dn and dn, andi immediate data l destination ? destination andi # , andi to ccr source l ccr ? ccr andi # , ccr andi to sr if supervisor state then source l sr ? sr else trap andi # , sr asl, asr destination shifted by ? destination asd dx,dy asd # ,dy asd bcc if (condition true) then pc + d ? pc bcc bchg ~ ( of destination) ? z; ~ ( of destination) ? of destination bchg dn, bchg # , bclr ~ ( of destination) ? z; 0 ? of destination bclr dn, bclr # , bkpt run breakpoint acknowledge cycle; trap as illegal instruction bkpt # bra pc + d ? pc bra bset ~ ( of destination) ? z; 1 ? of destination bset dn, bset # , bsr sp ?4 ? sp; pc ? (sp); pc + d ? pc bsr btst ( of destination) ? z; btst dn, btst # , chk if dn < 0 or dn > source then trap chk ,dn clr 0 ? destination clr cmp destination?ource ? cc cmp ,dn cmpa destination?ource cmpa ,an cmpi destination ?mmediate data cmpi # , cmpm destination?ource ? cc cmpm (ay)+, (ax)+ dbcc if condition false then (dn ?1 ? dn; if dn 1 ? then pc + d ? pc) dbcc dn,
2-12 m68000 8-/16-/32-bit microprocessor user? manual motorola table 2-2. instruction set summary (sheet 2 of 4) opcode operation syntax divs destination/source ? destination divs.w ,dn 32/16 ? 16r:16q divu destination/source ? destination divu.w ,dn 32/16 ? 16r:16q eor source ? destination ? destination eor dn, eori immediate data ? destination ? destination eori # , eori to ccr source ? ccr ? ccr eori # ,ccr eori to sr if supervisor state then source ? sr ? sr else trap eori # ,sr exg rx ? ry exg dx,dy exg ax,ay exg dx,ay exg ay,dx ext destination sign-extended ? destination ext.w dn extend byte to word ext.l dn extend word to long word illegal ssp ?2 ? ssp; vector offset ? (ssp); ssp ?4 ? ssp; pc ? (ssp); ssp ?2 ? ssp; sr ? (ssp); illegal instruction vector address ? pc illegal jmp destination address ? pc jmp jsr sp ?4 ? sp; pc ? (sp) destination address ? pc jsr lea ? an lea ,an link sp 4 ? sp; an ? (sp) sp ? an, sp + d ? sp link an, # lsl,lsr destination shifted by ? destination lsd 1 dx,dy lsd 1 # ,dy lsd 1 move source ? destination move , movea source ? destination movea ,an move from ccr ccr ? destination move ccr, move to ccr source ? ccr move ,ccr move from sr sr ? destination if supervisor state then sr ? destination else trap (MC68010 only) move sr, move to sr if supervisor state then source ? sr else trap move ,sr
motorola m68000 8-/16-/32-bit microprocessor user? manual 2-13 table 2-2. instruction set summary (sheet 3 of 4) opcode operation syntax move usp if supervisor state then usp ? an or an ? usp else trap move usp,an move an,usp movec if supervisor state then rc ? rn or rn ? rc else trap movec rc,rn movec rn,rc movem registers ? destination source ? registers movem register list, movem ,register list movep source ? destination movep dx,(d,ay) movep (d,ay),dx moveq immediate data ? destination moveq # ,dn moves if supervisor state then rn ? destination [dfc] or source [sfc] ? rn else trap moves rn, moves ,rn muls source destination ? destination muls.w ,dn 16 x 16 ? 32 mulu source destination ? destination mulu.w ,dn 16 x 16 ? 32 nbcd 0 (destination 10 ) ?x ? destination nbcd neg 0 ?(destination) ? destination neg negx 0 (destination) ?x ? destination negx nop none nop not ~destination ? destination not or source v destination ? destination or ,dn or dn, ori immediate data v destination ? destination ori # , ori to ccr source v ccr ? ccr ori # ,ccr ori to sr if supervisor state then source v sr ? sr else trap ori # ,sr pea sp ?4 ? sp; ? (sp) pea reset if supervisor state then assert reset line else trap reset rol, ror destination rotated by ? destination rod 1 rx,dy rod 1 # ,dy rod 1 roxl, roxr destination rotated with x by ? destination roxd 1 dx,dy roxd 1 # ,dy roxd 1 rtd (sp) ? pc; sp + 4 + d ? sp rtd #
2-14 m68000 8-/16-/32-bit microprocessor user? manual motorola table 2-2. instruction set summary (sheet 4 of 4) opcode operation syntax rte if supervisor state then (sp) ? sr; sp + 2 ? sp; (sp) ? pc; sp + 4 ? sp; restore state and deallocate stack according to (sp) else trap rte rtr (sp) ? ccr; sp + 2 ? sp; (sp) ? pc; sp + 4 ? sp rtr rts (sp) ? pc; sp + 4 ? sp rts sbcd destination 10 ?source 10 ?x ? destination sbcd dx,dy sbcd ?ax),?ay) scc if condition true then 1s ? destination else 0s ? destination scc stop if supervisor state then immediate data ? sr; stop else trap stop # sub destination ?source ? destination sub ,dn sub dn, suba destination ?source ? destination suba ,an subi destination ?immediate data ? destination subi # , subq destination ?immediate data ? destination subq # , subx destination ?source ?x ? destination subx dx,dy subx ?ax),?ay) swap register [31:16] ? register [15:0] swap dn tas destination tested ? condition codes; 1 ? bit 7 of destination tas trap ssp ?2 ? ssp; format/offset ? (ssp); ssp ?4 ? ssp; pc ? (ssp); ssp? ? ssp; sr ? (ssp); vector address ? pc trap # trapv if v then trap trapv tst destination tested ? condition codes tst unlk an ? sp; (sp) ? an; sp + 4 ? sp unlk an note: d is direction, l or r.
motorola m68000 8-/16-/32-bit microprocessors user's manual 3- 1 section 3 signal description this section contains descriptions of the input and output signals. the input and output signals can be functionally organized into the groups shown in figure 3-1 (for the mc68000, the mc68hc000 and the MC68010), figure 3-2 ( for the mc68hc001), figure 3-3 (for the mc68ec000), figure 3-4 (for the mc68008, 48-pin version), and figure 3-5 (for the mc68008, 52-pin version). the following paragraphs provide brief descriptions of the signals and references (where applicable) to other paragraphs that contain more information about the signals. note the terms assertion and negation are used extensively in this manual to avoid confusion when describing a mixture of "active-low" and "active-high" signals. the term assert or assertion is used to indicate that a signal is active or true, independently of whether that level is represented by a high or low voltage. the term negate or negation is used to indicate that a signal is inactive or false. v cc (2) gnd(2) clk address bus a23?1 data bus d15?0 as r/w uds lds dtack asynchronous bus control br bg bgack ipl1 ipl2 interrupt control bus arbitration control fc1 fc2 e vma vpa berr reset halt processor status mc6800 peripheral control system control ipl0 fc0 figure 3-1. input and output signals (mc68000, mc68hc000 and MC68010)
3- 2 m68000 8-/16-/32-bit microprocessors user's manual motorola v cc (2) gnd(2) clk address bus a23?0 data bus d15?0 as r/w uds lds dtack asynchronous bus control br bg bgack ipl1 ipl2 interrupt control bus arbitration control fc1 fc2 e vma vpa berr reset halt processor status mc6800 peripheral control system control ipl0 fc0 mode figure 3-2. input and output signals (mc68hc001) v cc (2) gnd(2) clk address bus a23?0 data bus d15?0 as r/w uds lds dtack asynchronous bus control br bg ipl1 ipl2 interrupt control bus arbitration control fc1 fc2 berr reset halt processor status system control ipl0 fc0 mode avec mc68ec000 figure 3-3. input and output signals (mc68ec000)
motorola m68000 8-/16-/32-bit microprocessors user's manual 3- 3 ipl2/ipl0 address bus a19?0 data bus d7?0 as r/w ds dtack br bg ipl1 e vpa asynchronous bus control interrupt control bus arbitration control mc6800 peripheral control v cc (2) gnd(2) clk fc0 fc1 fc2 berr reset halt processor status system control mc6808 figure 3-4. input and output signals (mc68008, 48-pin version) a21?0 bgack ipl2 address bus data bus d7?0 as r/w ds dtack br bg ipl1 e vpa asynchronous bus control interrupt control bus arbitration control mc6800 peripheral control v cc gnd(2) clk fc0 fc1 fc2 berr reset halt processor status system control mc68008 ipl0 figure 3-5. input and output signals (mc68008, 52-pin version) 3.1 address bus (a23?1) this 23-bit, unidirectional, three-state bus is capable of addressing 16 mbytes of data. this bus provides the address for bus operation during all cycles except interrupt acknowledge cycles and breakpoint cycles. during interrupt acknowledge cycles, address lines a1, a2, and a3 provide the level number of the interrupt being acknowledged, and address lines a23?4 are driven to logic high.
3- 4 m68000 8-/16-/32-bit microprocessors user's manual motorola address bus (a23?0) this 24-bit, unidirectional, three-state bus is capable of addressing 16 mbytes of data. this bus provides the address for bus operation during all cycles except interrupt acknowledge cycles and breakpoint cycles. during interrupt acknowledge cycles, address lines a1, a2, and a3 provide the level number of the interrupt being acknowledged, and address lines a23?4 and a0 are driven to logic high. in 16-bit mode, a0 is always driven high. mc68008 address bus the unidirectional, three-state buses in the two versions of the mc68008 differ from each other and from the other processor bus only in the number of address lines and the addressing range. the 20-bit address (a19?0) of the 48-pin version provides a 1- mbyte address space; the 52-pin version supports a 22-bit address (a21?0), extending the address space to 4 mbytes. during an interrupt acknowledge cycle, the interrupt level number is placed on lines a1, a2, and a3. lines a0 and a4 through the most significant address line are driven to logic high. 3.2 data bus (d15?0; mc68008: d7?0) this bidirectional, three-state bus is the general-purpose data path. it is 16 bits wide in the all the processors except the mc68008 which is 8 bits wide. the bus can transfer and accept data of either word or byte length. during an interrupt acknowledge cycle, the external device supplies the vector number on data lines d7?0. the mc68ec000 and mc68hc001 use d7?0 in 8-bit mode, and d15?8 are undefined. 3.3 asynchronous bus control asynchronous data transfers are controlled by the following signals: address strobe, read/write, upper and lower data strobes, and data transfer acknowledge. these signals are described in the following paragraphs. address strobe ( as ). this three-state signal indicates that the information on the address bus is a valid address. read/write (r/ w ). this three-state signal defines the data bus transfer as a read or write cycle. the r/ w signal relates to the data strobe signals described in the following paragraphs. upper and lower data strobes ( uds , lds ). these three-state signals and r/ w control the flow of data on the data bus. table 3-1 lists the combinations of these signals and the corresponding data on the bus. when the r/ w line is high, the processor reads from the data bus. when the r/ w line is low, the processor drives the data bus. in 8-bit mode, uds is always forced high and the lds signal is used.
motorola m68000 8-/16-/32-bit microprocessors user's manual 3- 5 table 3-1. data strobe control of data bus uds lds r/ w d8?15 d0?7 high high no valid data no valid data low low high valid data bits 15? valid data bits 7? high low high no valid data valid data bits 7? low high high valid data bus 15? no valid data low low low valid data bits 15? valid data bits 7? high low low valid data bits 7?* valid data bits 7? low high low valid data bits 15? valid data bits 15?* *these conditions are a result of current implementation and may not appear on future devices. data strobe ( ds ) (mc68008) this three-state signal and r/ w control the flow of data on the data bus of the mc68008 . table 3-2 lists the combinations of these signals and the corresponding data on the bus. when the r/ w line is high, the processor reads from the data bus. when the r/ w line is low, the processor drives the data bus. table 3-2. data strobe control of data bus (mc68008) ds r/ w d0?7 1 no valid data 0 1 valid data bits 7? (read cycle) 0 0 valid data bits 7? (write cycle) data transfer acknowledge ( dtack ). this input signal indicates the completion of the data transfer. when the processor recognizes dtack during a read cycle, data is latched, and the bus cycle is terminated. when dtack is recognized during a write cycle, the bus cycle is terminated. 3.4 bus arbitration control the bus request, bus grant, and bus grant acknowledge signals form a bus arbitration circuit to determine which device becomes the bus master device. in the 48-pin version of the mc68008 and mc68ec000, no pin is available for the bus grant acknowledge signal; this microprocessor uses a two-wire bus arbitration scheme. all m68000 processors can use two-wire bus arbitration.
3- 6 m68000 8-/16-/32-bit microprocessors user's manual motorola bus request ( br ). this input can be wire-ored with bus request signals from all other devices that could be bus masters. this signal indicates to the processor that some other device needs to become the bus master. bus requests can be issued at any time during a cycle or between cycles. bus grant ( bg ). this output signal indicates to all other potential bus master devices that the processor will relinquish bus control at the end of the current bus cycle. bus grant acknowledge ( bgack ). this input indicates that some other device has become the bus master. this signal should not be asserted until the following conditions are met: 1. a bus grant has been received. 2. address strobe is inactive, which indicates that the microprocessor is not using the bus. 3. data transfer acknowledge is inactive, which indicates that neither memory nor peripherals are using the bus. 4. bus grant acknowledge is inactive, which indicates that no other device is still claiming bus mastership. the 48-pin version of the mc68008 has no pin available for the bus grant acknowledge signal and uses a two-wire bus arbitration scheme instead. if another device in a system supplies a bus grant acknowledge signal, the bus request input signal to the processor should be asserted when either the bus request or the bus grant acknowledge from that device is asserted. 3.5 interrupt control ( ipl0 , ipl1 , ipl2 ) these input signals indicate the encoded priority level of the device requesting an interrupt. level seven, which cannot be masked, has the highest priority; level zero indicates that no interrupts are requested. ipl0 is the least significant bit of the encoded level, and ipl2 is the most significant bit. for each interrupt request, these signals must remain asserted until the processor signals interrupt acknowledge (fc2?c0 and a19 a16 high) for that request to ensure that the interrupt is recognized. note the 48-pin version of the mc68008 has only two interrupt control signals: ipl0 / ipl2 and ipl1 . ipl0 / ipl2 is internally connected to both ipl0 and ipl2 , which provides four interrupt priority levels: levels 0, 2, 5, and 7. in all other respects, the interrupt priority levels in this version of the mc68008 are identical to those levels in the other microprocessors described in this manual.
motorola m68000 8-/16-/32-bit microprocessors user's manual 3- 7 3.6 system control the system control inputs are used to reset the processor, to halt the processor, and to signal a bus error to the processor. the outputs reset the external devices in the system and signal a processor error halt to those devices. the three system control signals are described in the following paragraphs. bus error ( berr ) this input signal indicates a problem in the current bus cycle. the problem may be the following: 1. no response from a device. 2. no interrupt vector number returned. 3. an illegal access request rejected by a memory management unit. 4. some other application-dependent error. either the processor retries the bus cycle or performs exception processing, as determined by interaction between the bus error signal and the halt signal. reset ( reset ) the external assertion of this bidirectional signal along with the assertion of halt starts a system initialization sequence by resetting the processor. the processor assertion of reset (from executing a reset instruction) resets all external devices of a system without affecting the internal state of the processor. to reset both the processor and the external devices, the reset and halt input signals must be asserted at the same time. halt ( halt ) an input to this bidirectional signal causes the processor to stop bus activity at the completion of the current bus cycle. this operation places all control signals in the inactive state and places all three-state lines in the high-impedance state (refer to table 3-4). when the processor has stopped executing instructions (in the case of a double bus fault condition, for example), the halt line is driven by the processor to indicate the condition to external devices. mode (mode) (mc68hc001/68ec000) the mode input selects between the 8-bit and 16-bit operating modes. if this input is grounded at reset, the processor will come out of reset in the 8-bit mode. if this input is tied high or floating at reset, the processor will come out of reset in the 16-bit mode. this input should be changed only at reset and must be stable two clocks after reset is negated. changing this input during normal operation may produce unpredictable results.
3- 8 m68000 8-/16-/32-bit microprocessors user's manual motorola 3.7 m6800 peripheral control these control signals are used to interface the asynchronous m68000 processors with the synchronous m6800 peripheral devices. these signals are described in the following paragraphs. enable (e) this signal is the standard enable signal common to all m6800 family peripheral devices. a single period of clock e consists of 10 mc68000 clock periods (six clocks low, four clocks high). this signal is generated by an internal ring counter that may come up in any state. (at power-on, it is impossible to guarantee phase relationship of e to clk.) the e signal is a free-running clock that runs regardless of the state of the mpu bus. valid peripheral address ( vpa ) this input signal indicates that the device or memory area addressed is an m6800 family device or a memory area assigned to m6800 family devices and that data transfer should be synchronized with the e signal. this input also indicates that the processor should use automatic vectoring for an interrupt. refer to appendix b m6800 peripheral interface . valid memory address ( vma ) this output signal indicates to m6800 peripheral devices that the address on the address bus is valid and that the processor is synchronized to the e signal. this signal only responds to a vpa input that identifies an m6800 family device. the mc68008 does not supply a vma signal. this signal can be produced by a transistor-to-transistor logic (ttl) circuit; an example is described in appendix b m6800 peripheral interface . 3.8 processor function codes (fc0, fc1, fc2) these function code outputs indicate the mode (user or supervisor) and the address space type currently being accessed, as shown in table 3-3. the function code outputs are valid whenever as is active.
motorola m68000 8-/16-/32-bit microprocessors user's manual 3- 9 table 3-3. function code outputs function code output fc2 fc1 fc0 address space type low low low (undefined, reserved) low low high user data low high low user program low high high (undefined, reserved) high low low (undefined, reserved) high low high supervisor data high high low supervisor program high high high cpu space 3.9 clock (clk) the clock input is a ttl-compatible signal that is internally buffered for development of the internal clocks needed by the processor. this clock signal is a constant frequency square wave that requires no stretching or shaping. the clock input should not be gated off at any time, and the clock signal must conform to minimum and maximum pulse-width times listed in section 10 electrical characteristics . 3.10 power supply (v cc and gnd) power is supplied to the processor using these connections. the positive output of the power supply is connected to the v cc pins and ground is connected to the gnd pins.
3- 10 m68000 8-/16-/32-bit microprocessors user's manual motorola 3.11 signal summary table 3-4 summarizes the signals discussed in the preceding paragraphs. table 3-4. signal summary hi-z signal name mnemonic input/output active state on halt on bus relinquish address bus a0?23 output high yes yes data bus d0?15 input/output high yes yes address strobe as output low no yes read/write r/ w output read-high write-low no yes data strobe ds output low no yes upper and lower data strobes uds , lds output low no yes data transfer acknowledge dtack input low no no bus request br input low no no bus grant bg output low no no bus grant acknowledge bgack input low no no interrupt priority level ipl 0, ipl 1, ipl 2 input low no no bus error berr input low no no mode mode input high reset reset input/output low no* no* halt halt input/output low no* no* enable e output high no no valid memory address vma output low no yes valid peripheral address vpa input low no no function code output fc0, fc1, fc2 output high no yes clock clk input high no no power input v cc input ground gnd input *open drain.
motorola m68000 8-/16-/32-bit microprocessors user's manual 4- 1 section 4 8-bit bus operation the following paragraphs describe control signal and bus operation for 8-bit operation during data transfer operations, bus arbitration, bus error and halt conditions, and reset operation. the 8-bit bus operations devices are the mc68008, mc68hc001 in 8-bit mode, and mc68ec000 in 8-bit mode. the mc68hc001 and mc68ec000 select 8-bit mode by grounding mode during reset. 4.1 data transfer operations transfer of data between devices involves the following signals: 1. address bus a0 through highest numbered address line 2. data bus d0 through d7 3. control signals the address and data buses are separate parallel buses used to transfer data using an asynchronous bus structure. in all cases, the bus master must deskew all signals it issues at both the start and end of a bus cycle. in addition, the bus master must deskew the acknowledge and data signals from the slave device. for the mc68hc001 and mc68ec000, uds is held negated and d15?8 are undefined in 8-bit mode. the following paragraphs describe the read, write, read-modify-write, and cpu space cycles. the indivisible read-modify-write cycle implements interlocked multiprocessor communications. a cpu space cycle is a special processor cycle. 4.1.1 read cycle during a read cycle, the processor receives one byte of data from the memory or from a peripheral device. when the data is received, the processor internally positions the byte appropriately. the 8-bit operation must perform two or four read cycles to access a word or long word, asserting the data strobe to read a single byte during each cycle. the address bus in 8-bit operation includes a0, which selects the appropriate byte for each read cycle. figure 4-1 and 4-2 illustrate the byte read-cycle operation.
4- 2 m68000 8-/16-/32-bit microprocessors user's manual motorola bus master address the device 1) set r/w to read 2) place function code on fc2?c0 3) place address on a23-a0 4) assert address strobe (as) 5) assert lower data strobe (lds) (ds on mc68008) acquire the data 1) latch data 2) negate lds (ds for mc68008) 3) negate as terminate the cycle input the data 1) decode address 2) place data on d7?0 3) assert data transfer acknowledge (dtack) 1) remove data from d7?0 2) negate dtack slave start next cycle figure 4-1. byte read-cycle flowchart s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 w w w w s5 s6 s7 clk fc2?c0 a23?0 as lds r/w dtack d7?0 read write 2 wait state read (ds) figure 4-2. read and write-cycle timing diagram
motorola m68000 8-/16-/32-bit microprocessors user's manual 4- 3 a bus cycle consists of eight states. the various signals are asserted during specific states of a read cycle, as follows: state 0 the read cycle starts in state 0 (s0). the processor places valid function codes on fc0?c2 and drives r/ w high to identify a read cycle. state 1 entering state 1 (s1), the processor drives a valid address on the address bus. state 2 on the rising edge of state 2 (s2), the processor asserts as and lds , or ds . state 3 during state 3 (s3), no bus signals are altered. state 4 during state 4 (s4), the processor waits for a cycle termination signal ( dtack or berr ) or vpa , an m6800 peripheral signal. when vpa is asserted during s4, the cycle becomes a peripheral cycle (refer to appendix b m6800 peripheral interface ). if neither termination signal is asserted before the falling edge at the end of s4, the processor inserts wait states (full clock cycles) until either dtack or berr is asserted. state 5 during state 5 (s5), no bus signals are altered. state 6 during state 6 (s6), data from the device is driven onto the data bus. state 7 on the falling edge of the clock entering state 7 (s7), the processor latches data from the addressed device and negates as and lds , or ds . at the rising edge of s7, the processor places the address bus in the high- impedance state. the device negates dtack or berr at this time. note during an active bus cycle, vpa and berr are sampled on every falling edge of the clock beginning with s4, and data is latched on the falling edge of s6 during a read cycle. the bus cycle terminates in s7, except when berr is asserted in the absence of dtack . in that case, the bus cycle terminates one clock cycle later in s9. 4.1.2 write cycle during a write cycle, the processor sends bytes of data to the memory or peripheral device. figures 4-3 and 4-4 illustrate the write-cycle operation the 8-bit operation performs two write cycles for a word write operation, issuing the data strobe signal during each cycle. the address bus includes the a0 bit to select the desired byte.
4- 4 m68000 8-/16-/32-bit microprocessors user's manual motorola bus master address the device 1) place function code on fc2?c0 2) place address on a23?0 3) assert address strobe (as) 4) set r/w to write 5) place data on d0?7 6) assert lower data strobe (lds) or ds 1) negate lds or ds 2) negate as 3) remove data from d7-d0 4) set r/w to read terminate the cycle input the data 1) decode address 2) store data on d7?0 3) assert data transfer acknowledge (dtack) slave start next cycle terminate output transfer 1) negate dtack figure 4-3. byte write-cycle flowchart s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 s5 s6 s7 clk fc2?c0 a23?0 as lds r/w dtack d7?0 even byte write odd byte write odd byte write figure 4-4. write-cycle timing diagram
motorola m68000 8-/16-/32-bit microprocessors user's manual 4- 5 the descriptions of the eight states of a write cycle are as follows: state 0 the write cycle starts in s0. the processor places valid function codes on fc2?c0 and drives r/ w high (if a preceding write cycle has left r/ w low). state 1 entering s1, the processor drives a valid address on the address bus. state 2 on the rising edge of s2, the processor asserts as and drives r/ w low. state 3 during s3, the data bus is driven out of the high-impedance state as the data to be written is placed on the bus. state 4 at the rising edge of s4, the processor asserts lds , or ds . the processor waits for a cycle termination signal ( dtack or berr ) or vpa , an m6800 peripheral signal. when vpa is asserted during s4, the cycle becomes a peripheral cycle (refer to appendix b m6800 peripheral interface ). if neither termination signal is asserted before the falling edge at the end of s4, the processor inserts wait states (full clock cycles) until either dtack or berr is asserted. state 5 during s5, no bus signals are altered. state 6 during s6, no bus signals are altered. state 7 on the falling edge of the clock entering s7, the processor negates as , lds , and ds . as the clock rises at the end of s7, the processor places the address and data buses in the high-impedance state, and drives r/ w high. the device negates dtack or berr at this time. 4.1.3 read-modify-write cycle. the read-modify-write cycle performs a read operation, modifies the data in the arithmetic logic unit, and writes the data back to the same address. the address strobe ( as ) remains asserted throughout the entire cycle, making the cycle indivisible. the test and set (tas) instruction uses this cycle to provide a signaling capability without deadlock between processors in a multiprocessing environment. the tas instruction (the only instruction that uses the read-modify-write cycle) only operates on bytes. thus, all read-modify-write cycles are byte operations. figure 4-5 and 4-6 illustrate the read-modify-write cycle operation.
4- 6 m68000 8-/16-/32-bit microprocessors user's manual motorola bus master address the device 1) set r/w to read 2) place function code on fc2?c0 3) place address on a23?0 4) assert address strobe (as) 5) assert lower data strobe (lds) (ds on mc68008) terminate the cycle input the data 1) decode address 2) place data on d7?0 3) assert data transfer acknowledge (dtack) slave start next cycle 1) remove data from d7?0 2) negate dtack 1) latch data 1) negate lds or ds 2) start data modification acquire the data start output transfer 1) set r/w to write 2) place data on d7?0 3) assert lower data strobe (lds) (ds on mc68008) terminate output transfer 1) negate ds or lds 2) negate as 3) remove data from d7?0 4) set r/w to read input the data 1) store data on d7?0 2) assert data transfer acknowledge (dtack) terminate the cycle 1) negate dtack figure 4-5. read-modify-write cycle flowchart
motorola m68000 8-/16-/32-bit microprocessors user's manual 4- 7 clk a23?0 as s0 s1 s2 s3 s4 s5 s6 s7 s8 s9 s10 s11 s12 s13 s14 s15 s16 s17 s18 s19 indivisible cycle ds or lds r/w dtack d7?0 fc2?c0 figure 4-6. read-modify-write cycle timing diagram the descriptions of the read-modify-write cycle states are as follows: state 0 the read cycle starts in s0. the processor places valid function codes on fc2?c0 and drives r/ w high to identify a read cycle. state 1 entering s1, the processor drives a valid address on the address bus. state 2 on the rising edge of s2, the processor asserts as and lds , or ds . state 3 during s3, no bus signals are altered. state 4 during s4, the processor waits for a cycle termination signal ( dtack or berr ) or vpa , an m6800 peripheral signal. when vpa is asserted during s4, the cycle becomes a peripheral cycle (refer to appendix b m6800 peripheral interface ). if neither termination signal is asserted before the falling edge at the end of s4, the processor inserts wait states (full clock cycles) until either dtack or berr is asserted. state 5 during s5, no bus signals are altered. state 6 during s6, data from the device are driven onto the data bus. state 7 on the falling edge of the clock entering s7, the processor accepts data from the device and negates lds , and ds . the device negates dtack or berr at this time. states 8?1 the bus signals are unaltered during s8?11, during which the arithmetic logic unit makes appropriate modifications to the data.
4- 8 m68000 8-/16-/32-bit microprocessors user's manual motorola state 12 the write portion of the cycle starts in s12. the valid function codes on fc2?c0, the address bus lines, as , and r/ w remain unaltered. state 13 during s13, no bus signals are altered. state 14 on the rising edge of s14, the processor drives r/ w low. state 15 during s15, the data bus is driven out of the high-impedance state as the data to be written are placed on the bus. state 16 at the rising edge of s16, the processor asserts lds or ds . the processor waits for dtack or berr or vpa , an m6800 peripheral signal. when vpa is asserted during s16, the cycle becomes a peripheral cycle (refer to appendix b m6800 peripheral interface ). if neither termination signal is asserted before the falling edge at the close of s16, the processor inserts wait states (full clock cycles) until either dtack or berr is asserted. state 17 during s17, no bus signals are altered. state 18 during s18, no bus signals are altered. state 19 on the falling edge of the clock entering s19, the processor negates as , lds , and ds . as the clock rises at the end of s19, the processor places the address and data buses in the high-impedance state, and drives r/ w high. the device negates dtack or berr at this time. 4.2 other bus operations refer to section 5 16-bit bus operations for information on the following items: cpu space cycle bus arbitration ?bus request ?bus grant ?bus acknowledgment bus control bus errors and halt operations reset operations asynchronous operations synchronous operations
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 1 section 5 16-bit bus operation the following paragraphs describe control signal and bus operation for 16-bit bus operations during data transfer operations, bus arbitration, bus error and halt conditions, and reset operation. the 16-bit bus operation devices are the mc68000, mc68hc000, MC68010, and the mc68hc001 and mc68ec000 in 16-bit mode. the mc68hc001 and mc68ec000 select 16-bit mode by pulling mode high or leave it floating during reset. 5.1 data transfer operations transfer of data between devices involves the following signals: 1. address bus a1 through highest numbered address line 2. data bus d0 through d15 3. control signals the address and data buses are separate parallel buses used to transfer data using an asynchronous bus structure. in all cases, the bus master must deskew all signals it issues at both the start and end of a bus cycle. in addition, the bus master must deskew the acknowledge and data signals from the slave device. the following paragraphs describe the read, write, read-modify-write, and cpu space cycles. the indivisible read-modify-write cycle implements interlocked multiprocessor communications. a cpu space cycle is a special processor cycle. 5.1.1 read cycle during a read cycle, the processor receives either one or two bytes of data from the memory or from a peripheral device. if the instruction specifies a word or long-word operation, the mc68000, mc68hc000, mc68hc001, mc68ec000, or MC68010 processor reads both upper and lower bytes simultaneously by asserting both upper and lower data strobes. when the instruction specifies byte operation, the processor uses the internal a0 bit to determine which byte to read and issues the appropriate data strobe. when a0 equals zero, the upper data strobe is issued; when a0 equals one, the lower data strobe is issued. when the data is received, the processor internally positions the byte appropriately. the word read-cycle flowchart is shown in figure 5-1 and the byte read-cycle flowchart is shown in figure 5-2. the read and write cycle timing is shown in figure 5-3 and the word and byte read-cycle timing diagram is shown in figure 5-4.
5- 2 m68000 8-/16-/32-bit microprocessors user's manual motorola bus master address the device 1) set r/w to read 2) place function code on fc2?c0 3) place address on a23?1 4) assert address strobe (as) 5) assert upper data strobe (uds) and lower data strobe (lds) acquire the data 1) latch data 2) negate uds and lds 3) negate as terminate the cycle input the data 1) decode address 2) place data on d15?0 3) assert data transfer acknowledge (dtack) 1) remove data from d15?0 2) negate dtack slave start next cycle figure 5-1. word read-cycle flowchart bus master address the device 1) set r/w to read 2) place function code on fc2?c0 3) place address on a23-a1 4) assert address strobe (as) 5) assert upper data strobe (uds) or lower data strobe (lds) (based on internal a0) acquire the data 1) latch data 2) negate uds and lds 3) negate as terminate the cycle input the data 1) decode address 2) place data on d7?0 or d15?8 (based on uds or lds) 3) assert data transfer acknowledge (dtack) 1) remove data from d7?0 or d15?8 2) negate dtack slave start next cycle figure 5-2. byte read-cycle flowchart
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 3 s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 w w w w s5 s6 s7 clk fc2?c0 a23?1 as uds lds r/w dtack d15?8 d7?0 read write 2 wait state read figure 5-3. read and write-cycle timing diagram s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 s5 s6 s7 *internal signal only clk fc2?c0 a23?1 as uds lds r/w dtack d15?8 d7?0 read write read a0 * figure 5-4. word and byte read-cycle timing diagram
5- 4 m68000 8-/16-/32-bit microprocessors user's manual motorola a bus cycle consists of eight states. the various signals are asserted during specific states of a read cycle, as follows: state 0 the read cycle starts in state 0 (s0). the processor places valid function codes on fc0?c2 and drives r/ w high to identify a read cycle. state 1 entering state 1 (s1), the processor drives a valid address on the address bus. state 2 on the rising edge of state 2 (s2), the processor asserts as and uds , lds , or ds . state 3 during state 3 (s3), no bus signals are altered. state 4 during state 4 (s4), the processor waits for a cycle termination signal ( dtack or berr ) or vpa , an m6800 peripheral signal. when vpa is asserted during s4, the cycle becomes a peripheral cycle (refer to appendix b m6800 peripheral interface ). if neither termination signal is asserted before the falling edge at the end of s4, the processor inserts wait states (full clock cycles) until either dtack or berr is asserted. state 5 during state 5 (s5), no bus signals are altered. state 6 during state 6 (s6), data from the device is driven onto the data bus. state 7 on the falling edge of the clock entering state 7 (s7), the processor latches data from the addressed device and negates as, uds , and lds . at the rising edge of s7, the processor places the address bus in the high- impedance state. the device negates dtack or berr at this time. note during an active bus cycle, vpa and berr are sampled on every falling edge of the clock beginning with s4, and data is latched on the falling edge of s6 during a read cycle. the bus cycle terminates in s7, except when berr is asserted in the absence of dtack . in that case, the bus cycle terminates one clock cycle later in s9. 5.1.2 write cycle during a write cycle, the processor sends bytes of data to the memory or peripheral device. if the instruction specifies a word operation, the processor issues both uds and lds and writes both bytes. when the instruction specifies a byte operation, the processor uses the internal a0 bit to determine which byte to write and issues the appropriate data strobe. when the a0 bit equals zero, uds is asserted; when the a0 bit equals one, lds is asserted.
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 5 the word and byte write-cycle timing diagram and flowcharts in figures 5-5, 5-6, and 5-7 applies directly to the mc68000, the mc68hc000, the mc68hc001 (in 16-bit mode), the mc68ec000 (in 16-bit mode), and the MC68010. bus master address the device 1) place function code on fc2?c0 2) place address on a23?1 3) assert address strobe (as) 4) set r/w to write 5) place data on d15?0 6) assert upper data strobe (uds) and lower data strobe (lds) terminate the cycle input the data 1) decode address 2) store data on d15?0 3) assert data transfer acknowledge (dtack) slave start next cycle 1) negate dtack terminate output transfer 1) negate uds and lds 2) negate as 3) remove data from d15?0 4) set r/w to read figure 5-5. word write-cycle flowchart bus master address the device 1) place function code on fc2?c0 2) place address on a23?1 3) assert address strobe (as) 4) set r/w to write 5) place data on d0?7 or d15?8 (according to internal a0) 6) assert upper data strobe (uds) or lower data strobe (lds) (based on internal a0) 1) negate uds and lds 2) negate as 3) remove data from d7-d0 or d15-d8 4) set r/w to read terminate the cycle input the data 1) decode address 2) store data on d7?0 if lds is asserted. store data on d15?8 if uds is asserted 3) assert data transfer acknowledge (dtack) slave start next cycle terminate output transfer 1) negate dtack figure 5-6. byte write-cycle flowchart
5- 6 m68000 8-/16-/32-bit microprocessors user's manual motorola s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 s5 s6 s7 *internal signal only a0 * clk fc2?c0 a23?1 as uds lds r/w dtack d15?8 d7?0 even byte write word write odd byte write figure 5-7. word and byte write-cycle timing diagram the descriptions of the eight states of a write cycle are as follows: state 0 the write cycle starts in s0. the processor places valid function codes on fc2?c0 and drives r/ w high (if a preceding write cycle has left r/ w low). state 1 entering s1, the processor drives a valid address on the address bus. state 2 on the rising edge of s2, the processor asserts as and drives r/ w low. state 3 during s3, the data bus is driven out of the high-impedance state as the data to be written is placed on the bus. state 4 at the rising edge of s4, the processor asserts uds , or lds . the processor waits for a cycle termination signal ( dtack or berr ) or vpa , an m6800 peripheral signal. when vpa is asserted during s4, the cycle becomes a peripheral cycle (refer to appendix b m6800 peripheral interface . if neither termination signal is asserted before the falling edge at the end of s4, the processor inserts wait states (full clock cycles) until either dtack or berr is asserted. state 5 during s5, no bus signals are altered. state 6 during s6, no bus signals are altered.
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 7 state 7 on the falling edge of the clock entering s7, the processor negates as , uds , or lds . as the clock rises at the end of s7, the processor places the address and data buses in the high-impedance state, and drives r/ w high. the device negates dtack or berr at this time. 5.1.3 read-modify-write cycle. the read-modify-write cycle performs a read operation, modifies the data in the arithmetic logic unit, and writes the data back to the same address. the address strobe ( as ) remains asserted throughout the entire cycle, making the cycle indivisible. the test and set (tas) instruction uses this cycle to provide a signaling capability without deadlock between processors in a multiprocessing environment. the tas instruction (the only instruction that uses the read-modify-write cycle) only operates on bytes. thus, all read-modify-write cycles are byte operations. the read-modify-write flowchart shown in figure 5-8 and the timing diagram in figure 5-9, applies to the mc68000, the mc68hc000, the mc68hc001 (in 16-bit mode), the mc68ec000 (in 16-bit mode), and the MC68010. bus master address the device 1) set r/w to read 2 ) place function code on fc2?c0 3 ) place address on a23?1 4 ) assert address strobe (as) 5 ) assert upper data strobe (uds) or lower data strobe (lds) terminate the cycle input the data 1) decode address 2 ) place data on d7?0 or d15?0 3 ) assert data transfer acknowledge (dtack) slave start next cycle 1) remove data from d7?0 or d15?8 2 ) negate dtack 1) latch data 1 ) negate uds and lds 2 ) start data modification acquire the data start output transfer 1) set r/w to write 2 ) place data on d7?0 or d15?8 3 ) assert upper data strobe (uds) or lower data strobe (lds) terminate output transfer 1) negate uds or lds 2 ) negate as 3 ) remove data from d7?0 or d15?8 4 ) set r/w to read input the data 1) store data on d7?0 or d15?8 2 ) assert data transfer acknowledge (dtack) terminate the cycle 1) negate dtack figure 5-8. read-modify-write cycle flowchart
5- 8 m68000 8-/16-/32-bit microprocessors user's manual motorola clk a23?1 as s0 s1 s2 s3 s4 s5 s6 s7 s8 s9 s10 s11 s12 s13 s14 s15 s16 s17 s18 s19 indivisible cycle uds or lds r/w dtack d15?8 fc2?c0 figure 5-9. read-modify-write cycle timing diagram the descriptions of the read-modify-write cycle states are as follows: state 0 the read cycle starts in s0. the processor places valid function codes on fc2?c0 and drives r/ w high to identify a read cycle. state 1 entering s1, the processor drives a valid address on the address bus. state 2 on the rising edge of s2, the processor asserts as and uds , or lds . state 3 during s3, no bus signals are altered. state 4 during s4, the processor waits for a cycle termination signal ( dtack or berr ) or vpa , an m6800 peripheral signal. when vpa is asserted during s4, the cycle becomes a peripheral cycle (refer to appendix b m6800 peripheral interface ). if neither termination signal is asserted before the falling edge at the end of s4, the processor inserts wait states (full clock cycles) until either dtack or berr is asserted. state 5 during s5, no bus signals are altered. state 6 during s6, data from the device are driven onto the data bus. state 7 on the falling edge of the clock entering s7, the processor accepts data from the device and negates uds , and lds . the device negates dtack or berr at this time. states 8?1 the bus signals are unaltered during s8?11, during which the arithmetic logic unit makes appropriate modifications to the data.
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 9 state 12 the write portion of the cycle starts in s12. the valid function codes on fc2?c0, the address bus lines, as , and r/ w remain unaltered. state 13 during s13, no bus signals are altered. state 14 on the rising edge of s14, the processor drives r/ w low. state 15 during s15, the data bus is driven out of the high-impedance state as the data to be written are placed on the bus. state 16 at the rising edge of s16, the processor asserts uds or lds . the processor waits for dtack or berr or vpa , an m6800 peripheral signal. when vpa is asserted during s16, the cycle becomes a peripheral cycle (refer to appendix b m6800 peripheral interface ). if neither termination signal is asserted before the falling edge at the close of s16, the processor inserts wait states (full clock cycles) until either dtack or berr is asserted. state 17 during s17, no bus signals are altered. state 18 during s18, no bus signals are altered. state 19 on the falling edge of the clock entering s19, the processor negates as , uds , and lds . as the clock rises at the end of s19, the processor places the address and data buses in the high-impedance state, and drives r/ w high. the device negates dtack or berr at this time. 5.1.4 cpu space cycle a cpu space cycle, indicated when the function codes are all high, is a special processor cycle. bits a16?19 of the address bus identify eight types of cpu space cycles. only the interrupt acknowledge cycle, in which a16?19 are high, applies to all the microprocessors described in this manual. the MC68010 defines an additional type of cpu space cycle, the breakpoint acknowledge cycle, in which a16?19 are all low. other configurations of a16?19 are reserved by motorola to define other types of cpu cycles used in other m68000 family microprocessors. figure 5-10 shows the encoding of cpu space addresses. breakpoint acknowledge (MC68010 only) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1111111111111111111111111111 111 11 1 interrupt acknowledge function code 2031 31 23 19 16 0 cpu space type field level 1 310 address bus figure 5-10. cpu space address encoding
5- 10 m68000 8-/16-/32-bit microprocessors user's manual motorola the interrupt acknowledge cycle places the level of the interrupt being acknowledged on address bits a3?1 and drives all other address lines high. the interrupt acknowledge cycle reads a vector number when the interrupting device places a vector number on the data bus and asserts dtack to acknowledge the cycle. the timing diagram for an interrupt acknowledge cycle is shown in figure 5-11. alternately, the interrupt acknowledge cycle can be autovectored. the interrupt acknowledge cycle is the same, except the interrupting device asserts vpa instead of dtack . for an autovectored interrupt, the vector number used is $18 plus the interrupt level. this is generated internally by the microprocessor when vpa (or avec ) is asserted on an interrupt acknowledge cycle. dtack and vpa ( avec ) should never be simultaneously asserted. clk fc2?c0 a23?4 as uds * lds r/w dtack d15?8 d7?0 ipl2?pl0 stack pcl (ssp) iack cycle (vector number acquisition) stack and vector fetch a3?1 although a vector number is one byte, both data strobes are asserted due to the microcode used for exception processing. the processor does not recognize anything on data lines d8 through d15 at this time. last bus cycle of instruction (read or write) s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 w w w w s5 s6 * ipl2?pl0 transition ipl2?pl0 sampled ipl2?pl0 valid internally figure 5-11. interrupt acknowledge cycle timing diagram
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 11 the breakpoint acknowledge cycle is performed by the MC68010 to provide an indication to hardware that a software breakpoint is being executed when the processor executes a breakpoint (bkpt) instruction. the processor neither accepts nor sends data during this cycle, which is otherwise similar to a read cycle. the cycle is terminated by either dtack , berr , or as an m6800 peripheral cycle when vpa is asserted, and the processor continues illegal instruction exception processing. figure 5-12 illustrates the timing diagram for the breakpoint acknowledge cycle. s0 s2 s4 s6 s0 s2 s4 s6 s0 s2 s4 s6 word read clk fc2?c0 a23?1 as uds lds r/w dtack d15?8 d7?0 breakpoint cycle stack pc low figure 5-12. breakpoint acknowledge cycle timing diagram 5.2 bus arbitration bus arbitration is a technique used by bus master devices to request, to be granted, and to acknowledge bus mastership. bus arbitration consists of the following: 1. asserting a bus mastership request 2. receiving a grant indicating that the bus is available at the end of the current cycle 3. acknowledging that mastership has been assumed there are two ways to arbitrate the bus, 3-wire and 2-wire bus arbitration. the mc68000, mc68hc000, mc68ec000, mc68hc001, mc68008, and MC68010 can do 2-wire bus arbitration. the mc68000, mc68hc000, mc68hc001, and MC68010 can do 3-wire bus arbitration. figures 5-13 and 5-15 show 3-wire bus arbitration and figures 5-14 and 5-16 show 2-wire bus arbitration. bus arbitration on all microprocessors, except the 48-pin mc68008 and mc68ec000, bgack must be pulled high for 2-wire bus arbitration.
5- 12 m68000 8-/16-/32-bit microprocessors user's manual motorola grant bus arbitration request the bus 1) assert bus request (br) requesting device 1) external arbitration deter- mines next bus master 2) next bus master waits for current cycle to complete 3) next bus master asserts bus grant acknowledge (bgack) to become new master 4) bus master negates br terminate arbitration 1) negate bgack processor 1) assert bus grant (bg) acknowledge bus mastership operate as bus master 1) perform data transfers (read and write cycles) according to the same rules the pro- cessor uses rearbitrate or resume processor operation release bus mastership 1) negate bg (and wait for bgack to be negated) figure 5-13. 3-wire bus arbitration cycle flowchart (not applicable to 48-pin mc68008 or mc68ec000)
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 13 grant bus arbitration request the bus 1) assert bus request (br) requesting device 1) negate bus request (br) processor 1) assert bus grant (bg) operate as bus master rearbitrate or resume processor operation release bus mastership acknowledge release of bus mastership 1) negate bus grant (bg) 1) external arbitration deter- mines next bus master 2) next bus master waits for current cycle to complete figure 5-14. 2-wire bus arbitration cycle flowchart clk fc2?c0 a23?1 as lds/ uds r/w dtack d15?0 processor dma device processor dma device br bg bgack figure 5-15. 3-wire bus arbitration timing diagram (not applicable to 48-pin mc68008 or mc68ec000)
5- 14 m68000 8-/16-/32-bit microprocessors user's manual motorola clk fc2?c0 a19?0 as ds r/w dtack d7?0 processor br bg s0 s6 s2 s4 s0 s2 s4 s6 s0 s2 s4 s6 s0 s2 s4 s6 dma device processor dma device figure 5-16. 2-wire bus arbitration timing diagram the timing diagram in figure 5-15 shows that the bus request is negated at the time that an acknowledge is asserted. this type of operation applies to a system consisting of a processor and one other device capable of becoming bus master. in systems having several devices that can be bus masters, bus request lines from these devices can be wire-ored at the processor, and more than one bus request signal could occur. the bus grant signal is negated a few clock cycles after the assertion of the bus grant acknowledge signal. however, if bus requests are pending, the processor reasserts bus grant for another request a few clock cycles after bus grant (for the previous request) is negated. in response to this additional assertion of bus grant, external arbitration circuitry selects the next bus master before the current bus master has completed the bus activity. the timing diagram in figure 5-15 also applies to a system consisting of a processor and one other device capable of becoming bus master. since the 48-pin version of the mc68008 and the mc68ec000 does not recognize a bus grant acknowledge signal, this processor does not negate bus grant until the current bus master has completed the bus activity. 5.2.1 requesting the bus external devices capable of becoming bus masters assert br to request the bus. this signal can be wire-ored (not necessarily constructed from open-collector devices) from any of the devices in the system that can become bus master. the processor, which is at a lower bus priority level than the external devices, relinquishes the bus after it completes the current bus cycle. the bus grant acknowledge signal on all the processors except the 48-pin mc68008 and mc68ec000 helps to prevent the bus arbitration circuitry from responding to noise on the
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 15 bus request signal. when no acknowledge is received before the bus request signal is negated, the processor continues the use of the bus. 5.2.2 receiving the bus grant the processor asserts bg as soon as possible. normally, this process immediately follows internal synchronization, except when the processor has made an internal decision to execute the next bus cycle but has not yet asserted as for that cycle. in this case, bg is delayed until as is asserted to indicate to external devices that a bus cycle is in progress. bg can be routed through a daisy-chained network or through a specific priority-encoded network. any method of external arbitration that observes the protocol can be used. 5.2.3 acknowledgment of mastership (3-wire bus arbitration only) upon receiving bg , the requesting device waits until as , dtack , and bgack are negated before asserting bgack . the negation of as indicates that the previous bus master has completed its cycle. (no device is allowed to assume bus mastership while as is asserted.) the negation of bgack indicates that the previous master has released the bus. the negation of dtack indicates that the previous slave has terminated the connection to the previous master. (in some applications, dtack might not be included in this function; general-purpose devices would be connected using as only.) when bgack is asserted, the asserting device is bus master until it negates bgack . bgack should not be negated until after the bus cycle(s) is complete. a device relinquishes control of the bus by negating bgack . the bus request from the granted device should be negated after bgack is asserted. if another bus request is pending, bg is reasserted within a few clocks, as described in 5.3 bus arbitration control . the processor does not perform any external bus cycles before reasserting bg . 5.3 bus arbitration control all asynchronous bus arbitration signals to the processor are synchronized before being used internally. as shown in figure 5-17, synchronization requires a maximum of one cycle of the system clock, assuming that the asynchronous input setup time (#47, defined in section 10 electrical characteristic ) has been met. the input asynchronous signal is sampled on the falling edge of the clock and is valid internally after the next falling edge.
5- 16 m68000 8-/16-/32-bit microprocessors user's manual motorola clk br (external) br (internal) 47 internal signal valid external signal sampled figure 5-17. external asynchronous signal synchronization bus arbitration control is implemented with a finite-state machine. state diagram (a) in figure 5-18 applies to all processors using 3-wire bus arbitration and state diagram (b) applies to processors using 2-wire bus arbitration, in which bgack is permanently negated internally or externally. the same finite-state machine is used, but it is effectively a two-state machine because bgack is always negated. in figure 5-18, input signals r and a are the internally synchronized versions of br and bgack . the bg output is shown as g, and the internal three-state control signal is shown as t. if t is true, the address, data, and control buses are placed in the high-impedance state when as is negated. all signals are shown in positive logic (active high), regardless of their true active voltage level. state changes (valid outputs) occur on the next rising edge of the clock after the internal signal is valid. a timing diagram of the bus arbitration sequence during a processor bus cycle is shown in figure 5-19. the bus arbitration timing while the bus is inactive (e.g., the processor is performing internal operations for a multiply instruction) is shown in figure 5-20. when a bus request is made after the mpu has begun a bus cycle and before as has been asserted (s0), the special sequence shown in figure 5-21 applies. instead of being asserted on the next rising edge of clock, bg is delayed until the second rising edge following its internal assertion.
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 17 ra xx ra ra ra xx r+a xa ra rx 1 1 r = bus request internal a = bus grant acknowledge internal g = bus grant t = three-state control to bus control logic x = don't care notes: 1. state machine will not change if the bus is s0 or s1. refer to 5.2.3. bus arbitration control. 2. the address bus will be placed in the high-impedance state if t is asserted and as is negated. r r r x r x r r (a) 3-wire bus arbitration (b) 2-wire bus arbitration gt gt gt gt ra ra ra ra xa ra gt ra gt gt gt gt gt gt gt state 1 state 0 state 4 state 2 state 3 figure 5-18. bus arbitration unit state diagrams figures 5-19, 5-20, and 5-21 applies to all processors using 3-wire bus arbitration. figures 5-22, 5-23, and 5-24 applies to all processors using 2-wire bus arbitration.
5- 18 m68000 8-/16-/32-bit microprocessors user's manual motorola s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 clk bus three-stated b g asserted b r valid interna l b r sampled b r asserted bus released from three state and p rocessor starts next bus cycle b gack negated internal b gack sampled b gack negated br bg bgack fc2?c0 a23?1 as uds lds r/w dtack d15?0 processor alternate bus master processor figure 5-19. 3-wire bus arbitration timing diagram?rocessor active
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 19 s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 clk bgack negated b g asserted and bus three stated b r valid internal b r sampled b r asserted br bg bgack fc2?c0 a23?1 as uds lds r/w dtack d15?0 processor bus released from three state and processor starts next bus cycle processor bus i nactive alternate bus master figure 5-20. 3-wire bus arbitration timing diagram?us inactive
5- 20 m68000 8-/16-/32-bit microprocessors user's manual motorola bus three-stated b g asserted b r valid interna l b r sampled b r asserted bus released from three state and p rocessor starts next bus cycle b gack negated internal b gack sampled b gack negated br bg bgack as uds lds r/w dtack d15?0 processor alternate bus master processor s0 s2 s4 s6 s0 s2 s4 s6 s0 clk fc2?c0 a23?1 figure 5-21. 3-wire bus arbitration timing diagram?pecial case
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 21 s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 clk bus three-stated bg asserted br valid internal br sampled br asserted bus released from three state and processor starts next bus cycle br negated internal br sampled br negated br bg bgack fc2?c0 a23?1 as uds lds r/w dtack d15?0 processor alternate bus master processor figure 5-22. 2-wire bus arbitration timing diagram?rocessor active
5- 22 m68000 8-/16-/32-bit microprocessors user's manual motorola s0 s1 s2 s3 s4 s5 s6 s7 s0 s1 s2 s3 s4 clk br negated bg asserted and bus three stated br valid internal br sampled br asserted br bg bgack fc2?c0 a23?1 as uds lds r/w dtack d15?0 bus released from three state and processor starts next bus cycle processor processor bus inactive alternate bus master figure 5-23. 2-wire bus arbitration timing diagram?us inactive
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 23 bus three-stated bg asserted br valid internal br sampled br asserted bus released from three state and processor starts next bus cycle br negated internal br sampled br negated br bg bgack as uds lds r/w dtack d15?0 s0 s2 s4 s6 s0 s2 s4 s6 s0 clk fc2?c0 a23?1 processor alternate bus master processor figure 5-24. 2-wire bus arbitration timing diagram?pecial case 5.4. bus error and halt operation in a bus architecture that requires a handshake from an external device, such as the asynchronous bus used in the m68000 family, the handshake may not always occur. a bus error input is provided to terminate a bus cycle in error when the expected signal is not asserted. different systems and different devices within the same system require different maximum-response times. external circuitry can be provided to assert the bus error signal after the appropriate delay following the assertion of address strobe. in a virtual memory system, the bus error signal can be used to indicate either a page fault or a bus timeout. an external memory management unit asserts bus error when the page that contains the required data is not resident in memory. the processor suspends execution of the current instruction while the page is loaded into memory. the MC68010 pushes enough information on the stack to be able to resume execution of the instruction following return from the bus error exception handler.
5- 24 m68000 8-/16-/32-bit microprocessors user's manual motorola the MC68010 also differs from the other microprocessors described in this manual regarding bus errors. the MC68010 can detect a late bus error signal asserted within one clock cycle after the assertion of data transfer acknowledge. when receiving a bus error signal, the processor can either initiate a bus error exception sequence or try running the cycle again. 5.4.1 bus error operation in all the microprocessors described in this manual, a bus error is recognized when dtack and halt are negated and berr is asserted. in the MC68010, a late bus error is also recognized when halt is negated, and dtack and berr are asserted within one clock cycle. when the bus error condition is recognized, the current bus cycle is terminated in s9 for a read cycle, a write cycle, or the read portion of a read-modify-write cycle. for the write portion of a read-modify-write cycle, the current bus cycle is terminated in s21. as long as berr remains asserted, the data and address buses are in the high-impedance state. figure 5-25 shows the timing for the normal bus error, and figure 5-26 shows the timing for the MC68010 late bus error. s0 s2 s4 s6 clk fc2?c0 a23?1 ww w w s8 as lds/uds r/w dtack d15?0 berr halt initiate bus error detection initiate bus error stacking response failure read figure 5-25. bus error timing diagram
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 25 s0 s2 s4 s6 clk fc2?c0 a23?1 as uds/lds r/w dtack d15?0 berr halt initiate bus error stacking bus error read cycle detection figure 5-26. delayed bus error timing diagram (MC68010) after the aborted bus cycle is terminated and berr is negated, the processor enters exception processing for the bus error exception. during the exception processing sequence, the following information is placed on the supervisor stack: 1. status register 2. program counter (two words, which may be up to five words past the instruction being executed) 3. error information the first two items are identical to the information stacked by any other exception. the error information differs for the MC68010. the mc68000, mc68hc000, mc68hc001, mc68ec000, and mc68008 stack bus error information to help determine and to correct the error. the MC68010 stacks the frame format and the vector offset followed by 22 words of internal register information. the return from exception (rte) instruction restores the internal register information so that the MC68010 can continue execution of the instruction after the error handler routine completes. after the processor has placed the required information on the stack, the bus error exception vector is read from vector table entry 2 (offset $08) and placed in the program counter. the processor resumes execution at the address in the vector, which is the first instruction in the bus error handler routine.
5- 26 m68000 8-/16-/32-bit microprocessors user's manual motorola note in the MC68010, if a read-modify-write operation terminates in a bus error, the processor reruns the entire read-modify-write operation when the rte instruction at the end of the bus error handler returns control to the instruction in error. the processor reruns the entire operation whether the error occurred during the read or write portion. 5.4.2 retrying the bus cycle the assertion of the bus error signal during a bus cycle in which halt is also asserted by an external device initiates a retry operation. figure 5-27 is a timing diagram of the retry operation. the delayed berr signal in the MC68010 also initiates a retry operation when halt is asserted by an external device. figure 5-28 shows the timing of the delayed operation. s0 s2 s4 s6 clk fc2-fc0 a23?1 s8 s0 s2 s4 s6 as lds/uds r/w dtack d15?0 berr halt 1 clock period 3 read halt retry figure 5-27. retry bus cycle timing diagram
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 27 s0 s2 s4 s6 clk fc2?c0 a23?1 s0 s2 s4 s6 as r/w dtack d0?15 berr halt uds lds retry halt read figure 5-28. delayed retry bus cycle timing diagram the processor terminates the bus cycle, then puts the address and data lines in the high- impedance state. the processor remains in this state until halt is negated. then the processor retries the preceding cycle using the same function codes, address, and data (for a write operation). berr should be negated at least one clock cycle before halt is negated. note to guarantee that the entire read-modify-write cycle runs correctly and that the write portion of the operation is performed without negating the address strobe, the processor does not retry a read-modify-write cycle. when a bus error occurs during a read-modify-write operation, a bus error operation is performed whether or not halt is asserted. 5.4.3 halt operation ( halt) halt performs a halt/run/single-step operation similar to the halt operation of an mc68000. when halt is asserted by an external device, the processor halts and remains halted as long as the signal remains asserted, as shown in figure 5-29.
5- 28 m68000 8-/16-/32-bit microprocessors user's manual motorola s0 s2 s4 s6 clk fc2?c0 a23?1 s0 s2 s4 s6 as r/w dtack d0?15 berr halt uds lds read halt retry figure 5-29. halt operation timing diagram while the processor is halted, the address bus and the data bus signals are placed in the high-impedance state. bus arbitration is performed as usual. should a bus error occur while halt is asserted, the processor performs the retry operation previously described. the single-step mode is derived from correctly timed transitions of halt . halt is negated to allow the processor to begin a bus cycle, then asserted to enter the halt mode when the cycle completes. the single-step mode proceeds through a program one bus cycle at a time for debugging purposes. the halt operation and the hardware trace capability allow tracing of either bus cycles or instructions one at a time. these capabilities and a software debugging package provide total debugging flexibility. 5.4.4 double bus fault when a bus error exception occurs, the processor begins exception processing by stacking information on the supervisor stack. if another bus error occurs during exception processing (i.e., before execution of another instruction begins) the processor halts and asserts halt . this is called a double bus fault. only an external reset operation can restart a processor halted due to a double bus fault. a retry operation does not initiate exception processing; a bus error during a retry operation does not cause a double bus fault. the processor can continue to retry a bus cycle indefinitely if external hardware requests.
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 29 a double bus fault occurs during a reset operation when a bus error occurs while the processor is reading the vector table (before the first instruction is executed). the reset operation is described in the following paragraph. 5.5 reset operation reset is asserted externally for the initial processor reset. subsequently, the signal can be asserted either externally or internally (executing a reset instruction). for proper external reset operation, halt must also be asserted. when reset and halt are driven by an external device, the entire system, including the processor, is reset. resetting the processor initializes the internal state. the processor reads the reset vector table entry (address $00000) and loads the contents into the supervisor stack pointer (ssp). next, the processor loads the contents of address $00004 (vector table entry 1) into the program counter. then the processor initializes the interrupt level in the status register to a value of seven. in the MC68010, the processor also clears the vector base register to $00000. no other register is affected by the reset sequence. figure 5-30 shows the timing of the reset operation. t 4 clocks 23456 notes: 1. internal start-up time 2. ssp high read in here 3. ssp low read in here 4. pc high read in here 5. pc low read in here 6. first instruction fetched here bus state unknown: all control signals inactive. data bus in read mode: clk + 5 volts v cc reset halt bus cycles < t 100 milliseconds 3 1 figure 5-30. reset operation timing diagram the reset instruction causes the processor to assert reset for 124 clock periods to reset the external devices of the system. the internal state of the processor is not affected. neither the status register nor any of the internal registers is affected by an internal reset operation. all external devices in the system should be reset at the completion of the reset instruction. for the initial reset, reset and halt must be asserted for at least 100 ms. for a subsequent external reset, asserting these signals for 10 clock cycles or longer resets the processor. however, an external reset signal that is asserted while the processor is
5- 30 m68000 8-/16-/32-bit microprocessors user's manual motorola executing a reset instruction is ignored. since the processor asserts the reset signal for 124 clock cycles during execution of a reset instruction, an external reset should assert reset for at least 132 clock periods. 5.6 the relationship of dtack , berr , and halt to properly control termination of a bus cycle for a retry or a bus error condition, dtack , berr , and halt should be asserted and negated on the rising edge of the processor clock. this relationship assures that when two signals are asserted simultaneously, the required setup time (specification #47, section 9 electrical characteristics ) for both of them is met during the same bus state. external circuitry should be designed to incorporate this precaution. a related specification, #48, can be ignored when dtack , berr , and halt are asserted and negated on the rising edge of the processor clock. the possible bus cycle termination can be summarized as follows (case numbers refer to table 5-5). normal termination: dtack is asserted. berr and halt remain negated (case 1). halt termination: halt is asserted coincident with or preceding dtack , and berr remains negated (case 2). bus error termination: berr is asserted in lieu of, coincident with, or preceding dtack (case 3). in the MC68010, the late bus error also, berr is asserted following dtack (case 4). halt remains negated and berr is negated coincident with or after dtack . retry termination: halt and berr asserted in lieu of, coincident with, or before dtack (case 5). in the MC68010, the late retry also, berr and halt are asserted following dtack (case 6). berr is negated coincident with or after dtack . halt must be held at least one cycle after berr . table 5-1 shows the details of the resulting bus cycle termination in the m68000 microprocessors for various combinations of signal sequences.
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 31 table 5-1. dtack , berr , and halt assertion results case no. control signal asserted on rising edge of state mc68000/mc68hc000/001 ec000/mc68008 results MC68010 results n n+2 1 dtack berr halt a na na s na x normal cycle terminate and continue. normal cycle terminate and continue. 2 dtack berr halt a na a/s s na s normal cycle terminate and halt. continue when halt negated. normal cycle terminate and halt. continue when halt negated. 3 dtack berr halt x a na x s na terminate and take bus error trap. terminate and take bus error trap. 4 dtack berr halt a na na s a na normal cycle terminate and continue. terminate and take bus error trap. 5 dtack berr halt x a a/s x s s terminate and retry when halt removed. terminate and retry when halt removed. 6 dtack berr halt a na na s a a normal cycle terminate and continue. terminate and retry when halt removed. legend: n the number of the current even bus state (e.g., s4, s6, etc.) a signal asserted in this bus state na signal not asserted in this bus state x don't care s signal asserted in preceding bus state and remains asserted in this state note: all operations are subject to relevant setup and hold times. the negation of berr and halt under several conditions is shown in table 5-6. ( dtack is assumed to be negated normally in all cases; for reliable operation, both dtack and berr should be negated when address strobe is negated). example a: a system uses a watchdog timer to terminate accesses to unused address space. the timer asserts berr after timeout (case 3). example b: a system uses error detection on random-access memory (ram) contents. the system designer may: 1. delay dtack until the data is verified. if data is invalid, return berr and halt simultaneously to retry the error cycle (case 5). 2. delay dtack until the data is verified. if data is invalid, return berr at the same time as dtack (case 3). 3. for an MC68010, return dtack before data verification. if data is invalid, assert berr and halt to retry the error cycle (case 6).
5- 32 m68000 8-/16-/32-bit microprocessors user's manual motorola 4. for an MC68010, return dtack before data verification. if data is invalid, assert berr on the next clock cycle (case 4). table 5-6. berr and halt negation results conditions of termination in negated on rising edge of state table 4-4 control signal n n+2 results?ext cycle bus error berr halt or or takes bus error trap. rerun berr halt or illegal sequence; usually traps to vector number 0. rerun berr halt reruns the bus cycle. normal berr halt ?r may lengthen next cycle. normal berr halt ?r none if next cycle is started, it will be terminated as a bus error. ?= signal is negated in this bus state. 5.7 asynchronous operation to achieve clock frequency independence at a system level, the bus can be operated in an asynchronous manner. asynchronous bus operation uses the bus handshake signals to control the transfer of data. the handshake signals are as , uds , lds , ds (mc68008 only), dtack , berr , halt , avec (mc68ec000 only), and vpa (only for m6800 peripheral cycles). as indicates the start of the bus cycle, and uds , lds , and ds signal valid data for a write cycle. after placing the requested data on the data bus (read cycle) or latching the data (write cycle), the slave device (memory or peripheral) asserts dtack to terminate the bus cycle. if no device responds or if the access is invalid, external control logic asserts berr , or berr and halt , to abort or retry the cycle. figure 5-31 shows the use of the bus handshake signals in a fully asynchronous read cycle. figure 5-32 shows a fully asynchronous write cycle. as r/w dtack uds/lds data addr figure 5-31. fully asynchronous read cycle
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 33 addr as r/w uds/lds data dtack figure 5-32. fully asynchronous write cycle in the asynchronous mode, the accessed device operates independently of the frequency and phase of the system clock. for example, the mc68681 dual universal asynchronous receiver/transmitter (duart) does not require any clock-related information from the bus master during a bus transfer. asynchronous devices are designed to operate correctly with processors at any clock frequency when relevant timing requirements are observed. a device can use a clock at the same frequency as the system clock (e.g., 8, 10, or 12.5, 16, and 20mhz), but without a defined phase relationship to the system clock. this mode of operation is pseudo-asynchronous; it increases performance by observing timing parameters related to the system clock frequency without being completely synchronous with that clock. a memory array designed to operate with a particular frequency processor but not driven by the processor clock is a common example of a pseudo-asynchronous device. the designer of a fully asynchronous system can make no assumptions about address setup time, which could be used to improve performance. with the system clock frequency known, the slave device can be designed to decode the address bus before recognizing an address strobe. parameter #11 (refer to section 10 electrical characteristics ) specifies the minimum time before address strobe during which the address is valid. in a pseudo-asynchronous system, timing specifications allow dtack to be asserted for a read cycle before the data from a slave device is valid. the length of time that dtack may precede data is specified as parameter #31. this parameter must be met to ensure the validity of the data latched into the processor. no maximum time is specified from the assertion of as to the assertion of dtack . during this unlimited time, the processor inserts wait cycles in one-clock-period increments until dtack is recognized. figure 5-33 shows the important timing parameters for a pseudo-asynchronous read cycle.
5- 34 m68000 8-/16-/32-bit microprocessors user's manual motorola addr as r/w uds/lds data dtack 11 17 31 28 29 figure 5-33. pseudo-asynchronous read cycle during a write cycle, after the processor asserts as but before driving the data bus, the processor drives r/ w low. parameter #55 specifies the minimum time between the transition of r/ w and the driving of the data bus, which is effectively the maximum turnoff time for any device driving the data bus. after the processor places valid data on the bus, it asserts the data strobe signal(s). a data setup time, similar to the address setup time previously discussed, can be used to improve performance. parameter #29 is the minimum time a slave device can accept valid data before recognizing a data strobe. the slave device asserts dtack after it accepts the data. parameter #25 is the minimum time after negation of the strobes during which the valid data remains on the address bus. parameter #28 is the maximum time between the negation of the strobes by the processor and the negation of dtack by the slave device. if dtack remains asserted past the time specified by parameter #28, the processor may recognize it as being asserted early in the next bus cycle and may terminate that cycle prematurely. figure 5-34 shows the important timing specifications for a pseudo-asynchronous write cycle.
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 35 addr as r/w uds/lds data dtack 11 55 22 26 28 29 20a figure 5-34. pseudo-asynchronous write cycle in the MC68010, the berr signal can be delayed after the assertion of dtack . specification #48 is the maximum time between assertion of dtack and assertion of berr. if this maximum delay is exceeded, operation of the processor may be erratic. 5.8 synchronous operation in some systems, external devices use the system clock to generate dtack and other asynchronous input signals. this synchronous operation provides a closely coupled design with maximum performance, appropriate for frequently accessed parts of the system. for example, memory can operate in the synchronous mode, but peripheral devices operate asynchronously. for a synchronous device, the designer uses explicit timing information shown in section 10 electrical characteristics . these specifications define the state of all bus signals relative to a specific state of the processor clock. the standard m68000 bus cycle consists of four clock periods (eight bus cycle states) and, optionally, an integral number of clock cycles inserted as wait states. wait states are inserted as required to allow sufficient response time for the external device. the following state-by-state description of the bus cycle differs from those descriptions in 5.1.1 read cycle and 5.1.2 write cycle by including information about the important timing parameters that apply in the bus cycle states. state 0 the bus cycle starts in s0, during which the clock is high. at the rising edge of s0, the function code for the access is driven externally. parameter #6a defines the delay from this rising edge until the function codes are valid. also, the r/ w signal is driven high; parameter #18 defines the delay from the same rising edge to the transition of r/ w . the minimum value for parameter #18 applies to a read cycle preceded by a write cycle; this value
5- 36 m68000 8-/16-/32-bit microprocessors user's manual motorola is the maximum hold time for a low on r/ w beyond the initiation of the read cycle. state 1 entering s1, a low period of the clock, the address of the accessed device is driven externally with an assertion delay defined by parameter #6. state 2 on the rising edge of s2, a high period of the clock, as is asserted. during a read cycle, uds , lds , and/or ds is also asserted at this time. parameter #9 defines the assertion delay for these signals. for a write cycle, the r/ w signal is driven low with a delay defined by parameter #20. state 3 on the falling edge of the clock entering s3, the data bus is driven out of the high-impedance state with the data being written to the accessed device (in a write cycle). parameter #23 specifies the data assertion delay. in a read cycle, no signal is altered in s3. state 4 entering the high clock period of s4, uds , lds , and/or ds is asserted (during a write cycle) on the rising edge of the clock. as in s2 for a read cycle, parameter #9 defines the assertion delay from the rising edge of s4 for uds , lds , and/or ds . in a read cycle, no signal is altered by the processor during s4. until the falling edge of the clock at the end of s4 (beginning of s5), no response from any external device except reset is acknowledged by the processor. if either dtack or berr is asserted before the falling edge of s4 and satisfies the input setup time defined by parameter #47, the processor enters s5 and the bus cycle continues. if either dtack or berr is asserted but without meeting the setup time defined by parameter #47, the processor may recognize the signal and continue the bus cycle; the result is unpredictable. if neither dtack nor berr is asserted before the next rise of clock, the bus cycle remains in s4, and wait states (complete clock cycles) are inserted until one of the bus cycle termination is met. state 5 s5 is a low period of the clock, during which the processor does not alter any signal. state 6 s6 is a high period of the clock, during which data for a read operation is set up relative to the falling edge (entering s7). parameter #27 defines the minimum period by which the data must precede the falling edge. for a write operation, the processor changes no signal during s6. state 7 on the falling edge of the clock entering s7, the processor latches data and negates as and uds , lds , and/or ds during a read cycle. the hold time for these strobes from this falling edge is specified by parameter #12. the hold time for data relative to the negation of as and uds , lds , and/or ds is specified by parameter #29. for a write cycle, only as and uds , lds , and/or ds are negated; timing parameter #12 also applies.
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 37 on the rising edge of the clock, at the end of s7 (which may be the start of s0 for the next bus cycle), the processor places the address bus in the high-impedance state. during a write cycle, the processor also places the data bus in the high-impedance state and drives r/ w high. external logic circuitry should respond to the negation of the as and uds , lds , and/or ds by negating dtack and/or berr . parameter #28 is the hold time for dtack , and parameter #30 is the hold time for berr . figure 5-35 shows a synchronous read cycle and the important timing parameters that apply. the timing for a synchronous read cycle, including relevant timing parameters, is shown in figure 5-36. addr uds/lds r/w as clock dtack 6 9 s0 s1 s2 s3 s4 s5 s6 s7 s0 18 47 27 data figure 5-35. synchronous read cycle
5- 38 m68000 8-/16-/32-bit microprocessors user's manual motorola . addr uds/lds r/w as clock dtack 6 s0 s1 s2 s3 s4 s5 s6 s7 s0 18 data 23 53 47 9 figure 5-36. synchronous write cycle a key consideration when designing in a synchronous environment is the timing for the assertion of dtack and berr by an external device. to properly use external inputs, the processor must synchronize these signals to the internal clock. the processor must sample the external signal, which has no defined phase relationship to the cpu clock, which may be changing at sampling time, and must determine whether to consider the signal high or low during the succeeding clock period. successful synchronization requires that the internal machine receives a valid logic level (not a metastable signal), whether the input is high, low, or in transition. metastable signals propagating through synchronous machines can produce unpredictable operation. figure 5-37 is a conceptual representation of the input synchronizers used by the m68000 family processors. the input latches allow the input to propagate through to the output when e is high. when low, e latches the input. the three latches require one cycle of clk to synchronize an external signal. the high-gain characteristics of the devices comprising the latches quickly resolve a marginal signal into a valid state. d q g ext s igna l d q g d q g clk clk int s igna l figure 5-37. input synchronizers
motorola m68000 8-/16-/32-bit microprocessors user's manual 5- 39 parameter #47 of section 10 electrical characteristics is the asynchronous input setup time. signals that meet parameter #47 are guaranteed to be recognized at the next falling edge of the system clock. however, signals that do not meet parameter #47 are not guaranteed to be recognized. in addition, if dtack is recognized on a falling edge, valid data is latched into the processor (during a read cycle) on the next falling edge, provided the data meets the setup time required (parameter #27). when parameter #27 has been met, parameter #31 may be ignored. if dtack is asserted with the required setup time before the falling edge of s4, no wait states are incurred, and the bus cycle runs at its maximum speed of four clock periods. the late berr in an MC68010 that is operating in a synchronous mode must meet setup time parameter #27a. that is, when berr is asserted after dtack , berr must be asserted before the falling edge of the clock, one clock cycle after dtack is recognized. violating this requirement may cause the MC68010 to operate erratically.
motorola m68000 8-/16-/32-bit microprocessors user? manual 6- 1 section 6 exception processing this section describes operations of the processor outside the normal processing associated with the execution of instructions. the functions of the bits in the supervisor portion of the status register are described: the supervisor/user bit, the trace enable bit, and the interrupt priority mask. finally, the sequence of memory references and actions taken by the processor for exception conditions are described in detail. the processor is always in one of three processing states: normal, exception, or halted. the normal processing state is associated with instruction execution; the memory references are to fetch instructions and operands and to store results. a special case of the normal state is the stopped state, resulting from execution of a stop instruction. in this state, no further memory references are made. an additional, special case of the normal state is the loop mode of the MC68010, optionally entered when a test condition, decrement, and branch (dbcc) instruction is executed. in the loop mode, only operand fetches occur. see appendix a MC68010 loop mode operation . the exception processing state is associated with interrupts, trap instructions, tracing, and other exceptional conditions. the exception may be internally generated by an instruction or by an unusual condition arising during the execution of an instruction. externally, exception processing can be forced by an interrupt, by a bus error, or by a reset. exception processing provides an efficient context switch so that the processor can handle unusual conditions. the halted processing state is an indication of catastrophic hardware failure. for example, if during the exception processing of a bus error another bus error occurs, the processor assumes the system is unusable and halts. only an external reset can restart a halted processor. note that a processor in the stopped state is not in the halted state, nor vice versa. 6.1 privilege modes the processor operates in one of two levels of privilege: the supervisor mode or the user mode. the privilege mode determines which operations are legal. the mode is optionally used by an external memory management device to control and translate accesses. the mode is also used to choose between the supervisor stack pointer (ssp) and the user stack pointer (usp) in instruction references.
6- 2 m68000 8-/16-/32-bit microprocessors user's manual motorola the privilege mode is a mechanism for providing security in a computer system. programs should access only their own code and data areas and should be restricted from accessing information that they do not need and must not modify. the operating system executes in the supervisor mode, allowing it to access all resources required to perform the overhead tasks for the user mode programs. most programs execute in user mode, in which the accesses are controlled and the effects on other parts of the system are limited. 6.1.1 supervisor mode the supervisor mode has the higher level of privilege. the mode of the processor is determined by the s bit of the status register; if the s bit is set, the processor is in the supervisor mode. all instructions can be executed in the supervisor mode. the bus cycles generated by instructions executed in the supervisor mode are classified as supervisor references. while the processor is in the supervisor mode, those instructions that use either the system stack pointer implicitly or address register seven explicitly access the ssp. 6.1.2 user mode the user mode has the lower level of privilege. if the s bit of the status register is clear, the processor is executing instructions in the user mode. most instructions execute identically in either mode. however, some instructions having important system effects are designated privileged. for example, user programs are not permitted to execute the stop instruction or the reset instruction. to ensure that a user program cannot enter the supervisor mode except in a controlled manner, the instructions that modify the entire status register are privileged. to aid in debugging systems software, the move to user stack pointer (move to usp) and move from user stack pointer (move from usp) instructions are privileged. note to implement virtual machine concepts in the MC68010, the move from status register (move from sr), move to/from control register (movec), and move alternate address space (moves) instructions are also privileged. the bus cycles generated by an instruction executed in user mode are classified as user references. classifying a bus cycle as a user reference allows an external memory management device to translate the addresses of and control access to protected portions of the address space. while the processor is in the user mode, those instructions that use either the system stack pointer implicitly or address register seven explicitly access the usp. 6.1.3 privilege mode changes once the processor is in the user mode and executing instructions, only exception processing can change the privilege mode. during exception processing, the current state of the s bit of the status register is saved, and the s bit is set, putting the processor in the
motorola m68000 8-/16-/32-bit microprocessors user? manual 6- 3 supervisor mode. therefore, when instruction execution resumes at the address specified to process the exception, the processor is in the supervisor privilege mode. note the transition from supervisor to user mode can be accomplished by any of four instructions: return from exception (rte) (MC68010 only), move to status register (move to sr), and immediate to status register (andi to sr), and exclusive or immediate to status register (eori to sr). the rte instruction in the MC68010 fetches the new status register and program counter from the supervisor stack and loads each into its respective register. next, it begins the instruction fetch at the new program counter address in the privilege mode determined by the s bit of the new contents of the status register. the move to sr, andi to sr, and eori to sr instructions fetch all operands in the supervisor mode, perform the appropriate update to the status register, and then fetch the next instruction at the next sequential program counter address in the privilege mode determined by the new s bit. 6.1.4 reference classification when the processor makes a reference, it classifies the reference according to the encoding of the three function code output lines. this classification allows external translation of addresses, control of access, and differentiation of special processor states, such as cpu space (used by interrupt acknowledge cycles). table 6-1 lists the classification of references. table 6-1. reference classification function code output fc2 fc1 fc0 address space 0 0 0 (undefined, reserved)* 0 0 1 user data 0 1 0 user program 0 1 1 (undefined, reserved)* 1 0 0 (undefined, reserved)* 1 0 1 supervisor data 1 1 0 supervisor program 1 1 1 cpu space *address space 3 is reserved for user definition, while 0 and 4 are reserved for future use by motorola.
6- 4 m68000 8-/16-/32-bit microprocessors user's manual motorola 6.2 exception processing the processing of an exception occurs in four steps, with variations for different exception causes: 1. make a temporary copy of the status register and set the status register for exception processing. 2. obtain the exception vector. 3. save the current processor context. 4. obtain a new context and resume instruction processing. 6.2.1 exception vectors an exception vector is a memory location from which the processor fetches the address of a routine to handle an exception. each exception type requires a handler routine and a unique vector. all exception vectors are two words in length (see figure 6-1), except for the reset vector, which is four words long. all exception vectors reside in the supervisor data space, except for the reset vector, which is in the supervisor program space. a vector number is an 8-bit number that is multiplied by four to obtain the offset of an exception vector. vector numbers are generated internally or externally, depending on the cause of the exception. for interrupts, during the interrupt acknowledge bus cycle, a peripheral provides an 8-bit vector number (see figure 6-2) to the processor on data bus lines d7 d0. the processor forms the vector offset by left-shifting the vector number two bit positions and zero-filling the upper-order bits to obtain a 32-bit long-word vector offset. in the mc68000, the mc68hc000, mc68hc001, mc68ec000, and the mc68008, this offset is used as the absolute address to obtain the exception vector itself, which is shown in figure 6-3. note in the MC68010, the vector offset is added to the 32-bit vector base register (vbr) to obtain the 32-bit absolute address of the exception vector (see figure 6-4). since the vbr is set to zero upon reset, the MC68010 functions identically to the mc68000, mc68hc000, mc68hc001, mc68ec000, and mc68008 until the vbr is changed via the move control register movec instruction. new program counter (high) new program counter (low) a1=0 a1=1 word 0 word 1 even byte (a0=0) even byte (a0=0) figure 6-1. exception vector format
motorola m68000 8-/16-/32-bit microprocessors user? manual 6- 5 d15 d8 d7 d0 ignored v7 v6 v5 v4 v3 v2 v1 v0 where: v7 is the msb of the vector number v0 is the lsb of the vector number figure 6-2. peripheral vector number format a31 a10 a9 a8 a7 a6 a5 a4 a3 a2 a1 a0 all zeroes v7 v6 v5 v4 v3 v2 v1 v0 0 0 figure 6-3. address translated from 8-bit vector number (mc68000, mc68hc000, mc68hc001, mc68ec000, and mc68008) 31 31 0 0 10 all zeroes contents of vector base register v7 v6 v5 v4 v3 v2 v1 v0 0 0 exception vector address + figure 6-4. exception vector address calculation (MC68010) the actual address on the address bus is truncated to the number of address bits available on the bus of the particular implementation of the m68000 architecture. in all processors except the mc68008, this is 24 address bits. (a0 is implicitly encoded in the data strobes.) in the mc68008, the address is 20 or 22 bits in length. the memory map for exception vectors is shown in table 6-2. the vector table, table 6-2, is 512 words long (1024 bytes), starting at address 0 (decimal) and proceeding through address 1023 (decimal). the vector table provides 255 unique vectors, some of which are reserved for trap and other system function vectors. of the 255, 192 are reserved for user interrupt vectors. however, the first 64 entries are not protected, so user interrupt vectors may overlap at the discretion of the systems designer. 6.2.2 kinds of exceptions exceptions can be generated by either internal or external causes. the externally generated exceptions are the interrupts, the bus error, and reset. the interrupts are
6- 6 m68000 8-/16-/32-bit microprocessors user's manual motorola requests from peripheral devices for processor action; the bus error and reset inputs are used for access control and processor restart. the internal exceptions are generated by instructions, address errors, or tracing. the trap (trap), trap on overf low (trapv), check register against bounds (chk), and divide (div) instructions can generate exceptions as part of their instruction execution. in addition, illegal instructions, word fetches from odd addresses, and privilege violations cause exceptions. tracing is similar to a very high priority, internally generated interrupt following each instruction.
motorola m68000 8-/16-/32-bit microprocessors user? manual 6- 7 table 6-2. exception vector assignment vectors numbers address hex decimal dec hex space 6 assignment 0 0 0 000 sp reset: initial ssp 2 1 1 4 004 sp reset: initial pc 2 2 2 8 008 sd bus error 3 3 12 00c sd address error 4 4 16 010 sd illegal instruction 5 5 20 014 sd zero divide 6 6 24 018 sd chk instruction 7 7 28 01c sd trapv instruction 8 8 32 020 sd privilege violation 9 9 36 024 sd trace a 10 40 028 sd line 1010 emulator b 11 44 02c sd line 1111 emulator c 12 1 48 030 sd (unassigned, reserved) d 13 1 52 034 sd (unassigned, reserved) e 14 56 038 sd format error 5 f 15 60 03c sd uninitialized interrupt vector 10?7 16?3 1 64 040 sd (unassigned, reserved) 92 05c 18 24 96 060 sd spurious interrupt 3 19 25 100 064 sd level 1 interrupt autovector 1a 26 104 068 sd level 2 interrupt autovector 1b 27 108 06c sd level 3 interrupt autovector 1c 28 112 070 sd level 4 interrupt autovector 1d 29 116 074 sd level 5 interrupt autovector 1e 30 120 078 sd level 6 interrupt autovector 1f 31 124 07c sd level 7 interrupt autovector 20?f 32?7 128 080 sd trap instruction vectors 4 188 0bc 30?f 48?3 1 192 0c0 sd (unassigned, reserved) 255 0ff 40?f 64?55 256 100 sd user interrupt vectors 1020 3fc notes: 1. vector numbers 12, 13, 16?3, and 48?3 are reserved for future enhancements by motorola. no user peripheral devices should be assigned these numbers. 2. reset vector (0) requires four words, unlike the other vectors which only require two words, and is located in the supervisor program space. 3. the spurious interrupt vector is taken when there is a bus error indication during interrupt processing. 4. trap #n uses vector number 32+ n. 5. MC68010 only. this vector is unassigned, reserved on the mc68000 and mc68008. 6. sp denotes supervisor program space, and sd denotes supervisor data space.
6- 8 m68000 8-/16-/32-bit microprocessors user's manual motorola 6.2.3 multiple exceptions these paragraphs describe the processing that occurs when multiple exceptions arise simultaneously. exceptions can be grouped by their occurrence and priority. the group 0 exceptions are reset, bus error, and address error. these exceptions cause the instruction currently being executed to abort and the exception processing to commence within two clock cycles. the group 1 exceptions are trace and interrupt, privilege violations, and illegal instructions. trace and interrupt exceptions allow the current instruction to execute to completion, but pre-empt the execution of the next instruction by forcing exception processing to occur. a privilege-violating instruction or an illegal instruction is detected when it is the next instruction to be executed. the group 2 exceptions occur as part of the normal processing of instructions. the trap, trapv, chk, and zero divide exceptions are in this group. for these exceptions, the normal execution of an instruction may lead to exception processing. group 0 exceptions have highest priority, whereas group 2 exceptions have lowest priority. within group 0, reset has highest priority, followed by address error and then bus error. within group 1, trace has priority over external interrupts, which in turn takes priority over illegal instruction and privilege violation. since only one instruction can be executed at a time, no priority relationship applies within group 2. the priority relationship between two exceptions determines which is taken, or taken first, if the conditions for both arise simultaneously. therefore, if a bus error occurs during a trap instruction, the bus error takes precedence, and the trap instruction processing is aborted. in another example, if an interrupt request occurs during the execution of an instruction while the t bit is asserted, the trace exception has priority and is processed first. before instruction execution resumes, however, the interrupt exception is also processed, and instruction processing finally commences in the interrupt handler routine. a summary of exception grouping and priority is given in table 6-3. as a general rule, the lower the priority of an exception, the sooner the handler routine for that exception executes. for example, if simultaneous trap, trace, and interrupt exceptions are pending, the exception processing for the trap occurs first, followed immediately by exception processing for the trace and then for the interrupt. when the processor resumes normal instruction execution, it is in the interrupt handler, which returns to the trace handler, which returns to the trap execution handler. this rule does not apply to the reset exception; its handler is executed first even though it has the highest priority, because the reset operation clears all other exceptions.
motorola m68000 8-/16-/32-bit microprocessors user? manual 6- 9 table 6-3. exception grouping and priority group exception processing 0 reset address error bus error exception processing begins within two clock cycles 1 trace interrupt illegal privilege exception processing begins before the next instruction 2 trap, trapv, chk zero divide exception processing is started by normal instruction execution 6.2.4 exception stack frames exception processing saves the most volatile portion of the current processor context on the top of the supervisor stack. this context is organized in a format called the exception stack frame. although this information varies with the particular processor and type of exception, it always includes the status register and program counter of the processor when the exception occurred. the amount and type of information saved on the stack are determined by the processor type and exception type. exceptions are grouped by type according to priority of the exception. of the group 0 exceptions, the reset exception does not stack any information. the information stacked by a bus error or address error exception in the mc68000, mc68hc000, mc68hc001, mc68ec000, or mc68008 is described in 6.3.9.1 bus error and shown in figure 6-7. the mc68000, mc68hc000, mc68hc001, mc68ec000, and mc68008 group 1 and 2 exception stack frame is shown in figure 6-5. only the program counter and status register are saved. the program counter points to the next instruction to be executed after exception processing. the MC68010 exception stack frame is shown in figure 5-6. the number of words actually stacked depends on the exception type. group 0 exceptions (except reset) stack 29 words and group 1 and 2 exceptions stack four words. to support generic exception handlers, the processor also places the vector offset in the exception stack frame. the format code field allows the return from exception (rte) instruction to identify what information is on the stack so that it can be properly restored. table 6-4 lists the MC68010 format codes. although some formats are specific to a particular m68000 family processor, the format 0000 is always legal and indicates that just the first four words of the frame are present.
6- 10 m68000 8-/16-/32-bit microprocessors user's manual motorola even byte odd byte program counter low program counter high ssp 7 0 7 0 0 15 status register higher a ddres s figure 6-5. group 1 and 2 exception stack frame (mc68000, mc68hc000, mc68hc001, mc68ec000, and mc68008) program counter low program counter high sp 0 15 status register higher a ddres s vector offset format other information depending on exception figure 6-6. MC68010 stack frame
motorola m68000 8-/16-/32-bit microprocessors user? manual 6- 11 table 6-4. MC68010 format codes format code stacked information 0000 short format (4 words) 1000 long format (29 words) all others unassigned, reserved 6.2.5 exception processing sequence in the first step of exception processing, an internal copy is made of the status register. after the copy is made, the s bit of the status register is set, putting the processor into the supervisor mode. also, the t bit is cleared, which allows the exception handler to execute unhindered by tracing. for the reset and interrupt exceptions, the interrupt priority mask is also updated appropriately. in the second step, the vector number of the exception is determined. for interrupts, the vector number is obtained by a processor bus cycle classified as an interrupt acknowledge cycle. for all other exceptions, internal logic provides the vector number. this vector number is then used to calculate the address of the exception vector. the third step, except for the reset exception, is to save the current processor status. (the reset exception does not save the context and skips this step.) the current program counter value and the saved copy of the status register are stacked using the ssp. the stacked program counter value usually points to the next unexecuted instruction. however, for bus error and address error, the value stacked for the program counter is unpredictable and may be incremented from the address of the instruction that caused the error. group 1 and 2 exceptions use a short format exception stack frame (format = 0000 on the MC68010). additional information defining the current context is stacked for the bus error and address error exceptions. the last step is the same for all exceptions. the new program counter value is fetched from the exception vector. the processor then resumes instruction execution. the instruction at the address in the exception vector is fetched, and normal instruction decoding and execution is started. 6.3 processing of specific exceptions the exceptions are classified according to their sources, and each type is processed differently. the following paragraphs describe in detail the types of exceptions and the processing of each type. 6.3.1 reset the reset exception corresponds to the highest exception level. the processing of the reset exception is performed for system initiation and recovery from catastrophic failure. any processing in progress at the time of the reset is aborted and cannot be recovered. the processor is forced into the supervisor state, and the trace state is forced off. the
6- 12 m68000 8-/16-/32-bit microprocessors user's manual motorola interrupt priority mask is set at level 7. in the MC68010, the vbr is forced to zero. the vector number is internally generated to reference the reset exception vector at location 0 in the supervisor program space. because no assumptions can be made about the validity of register contents, in particular the ssp, neither the program counter nor the status register is saved. the address in the first two words of the reset exception vector is fetched as the initial ssp, and the address in the last two words of the reset exception vector is fetched as the initial program counter. finally, instruction execution is started at the address in the program counter. the initial program counter should point to the power- up/restart code. the reset instruction does not cause a reset exception; it asserts the reset signal to reset external devices, which allows the software to reset the system to a known state and continue processing with the next instruction. 6.3.2 interrupts seven levels of interrupt priorities are provided, numbered from 1?. all seven levels are available except for the 48-pin version for the mc68008. note the mc68008 48-pin version supports only three interrupt levels: 2, 5, and 7. level 7 has the highest priority. devices can be chained externally within interrupt priority levels, allowing an unlimited number of peripheral devices to interrupt the processor. the status register contains a 3- bit mask indicating the current interrupt priority, and interrupts are inhibited for all priority levels less than or equal to the current priority. an interrupt request is made to the processor by encoding the interrupt request levels 1? on the three interrupt request lines; all lines negated indicates no interrupt request. interrupt requests arriving at the processor do not force immediate exception processing, but the requests are made pending. pending interrupts are detected between instruction executions. if the priority of the pending interrupt is lower than or equal to the current processor priority, execution continues with the next instruction, and the interrupt exception processing is postponed until the priority of the pending interrupt becomes greater than the current processor priority. if the priority of the pending interrupt is greater than the current processor priority, the exception processing sequence is started. a copy of the status register is saved; the privilege mode is set to supervisor mode; tracing is suppressed; and the processor priority level is set to the level of the interrupt being acknowledged. the processor fetches the vector number from the interrupting device by executing an interrupt acknowledge cycle, which displays the level number of the interrupt being acknowledged on the address bus. if external logic requests an automatic vector, the processor internally generates a vector number corresponding to the interrupt level number. if external logic indicates a bus error, the interrupt is considered spurious, and the generated vector number references the spurious interrupt vector. the processor then proceeds with the usual exception processing, saving the format/offset word (MC68010 only), program counter, and status
motorola m68000 8-/16-/32-bit microprocessors user? manual 6- 13 register on the supervisor stack. the offset value in the format/offset word on the MC68010 is the vector number multiplied by four. the format is all zeros. the saved value of the program counter is the address of the instruction that would have been executed had the interrupt not been taken. the appropriate interrupt vector is fetched and loaded into the program counter, and normal instruction execution commences in the interrupt handling routine. priority level 7 is a special case. level 7 interrupts cannot be inhibited by the interrupt priority mask, thus providing a "nonmaskable interrupt" capability. an interrupt is generated each time the interrupt request level changes from some lower level to level 7. a level 7 interrupt may still be caused by the level comparison if the request level is a 7 and the processor priority is set to a lower level by an instruction. 6.3.3 uninitialized interrupt an interrupting device provides an m68000 interrupt vector number and asserts data transfer acknowledge ( dtack ), or asserts valid peripheral address ( vpa ), or auto vector ( avec ) , or bus error ( berr ) during an interrupt acknowledge cycle by the mc68000. if the vector register has not been initialized, the responding m68000 family peripheral provides vector number 15, the uninitialized interrupt vector. this response conforms to a uniform way to recover from a programming error. 6.3.4 spurious interrupt during the interrupt acknowledge cycle, if no device responds by asserting dtack or avec , vpa , berr should be asserted to terminate the vector acquisition. the processor separates the processing of this error from bus error by forming a short format exception stack and fetching the spurious interrupt vector instead of the bus error vector. the processor then proceeds with the usual exception processing. 6.3.5 instruction traps traps are exceptions caused by instructions; they occur when a processor recognizes an abnormal condition during instruction execution or when an instruction is executed that normally traps during execution. exception processing for traps is straightforward. the status register is copied; the supervisor mode is entered; and tracing is turned off. the vector number is internally generated; for the trap instruction, part of the vector number comes from the instruction itself. the format/offset word (MC68010 only), the program counter, and the copy of the status register are saved on the supervisor stack. the offset value in the format/offset word on the MC68010 is the vector number multiplied by four. the saved value of the program counter is the address of the instruction following the instruction that generated the trap. finally, instruction execution commences at the address in the exception vector. some instructions are used specifically to generate traps. the trap instruction always forces an exception and is useful for implementing system calls for user programs. the trapv and chk instructions force an exception if the user program detects a run-time error, which may be an arithmetic overflow or a subscript out of bounds.
6- 14 m68000 8-/16-/32-bit microprocessors user's manual motorola a signed divide (divs) or unsigned divide ( divu ) instruction forces an exception if a division operation is attempted with a divisor of zero. 6.3.6 illegal and unimplemented instructions illegal instruction is the term used to refer to any of the word bit patterns that do not match the bit pattern of the first word of a legal m68000 instruction. if such an instruction is fetched, an illegal instruction exception occurs. motorola reserves the right to define instructions using the opcodes of any of the illegal instructions. three bit patterns always force an illegal instruction trap on all m68000-family-compatible microprocessors. the patterns are: $4afa, $4afb, and $4afc. two of the patterns, $4afa and $4afb, are reserved for motorola system products. the third pattern, $4afc, is reserved for customer use (as the take illegal instruction trap (illegal) instruction). note in addition to the previously defined illegal instruction opcodes, the MC68010 defines eight breakpoint (bkpt) instructions with the bit patterns $4848?484f. these instructions cause the processor to enter illegal instruction exception processing as usual. however, a breakpoint acknowledge bus cycle, in which the function code lines (fc2?c0) are high and the address lines are all low, is also executed before the stacking operations are performed. the processor does not accept or send any data during this cycle. whether the breakpoint acknowledge cycle is terminated with a dtack , berr , or vpa signal, the processor continues with the illegal instruction processing. the purpose of this cycle is to provide a software breakpoint that signals to external hardware when it is executed. word patterns with bits 15?2 equaling 1010 or 1111 are distinguished as unimplemented instructions, and separate exception vectors are assigned to these patterns to permit efficient emulation. opcodes beginning with bit patterns equaling 1111 (line f) are implemented in the mc68020 and beyond as coprocessor instructions. these separate vectors allow the operating system to emulate unimplemented instructions in software. exception processing for illegal instructions is similar to that for traps. after the instruction is fetched and decoding is attempted, the processor determines that execution of an illegal instruction is being attempted and starts exception processing. the exception stack frame for group 2 is then pushed on the supervisor stack, and the illegal instruction vector is fetched.
motorola m68000 8-/16-/32-bit microprocessors user? manual 6- 15 6.3.7 privilege violations to provide system security, various instructions are privileged. an attempt to execute one of the privileged instructions while in the user mode causes an exception. the privileged instructions are as follows: and immediate to sr move usp eor immediate to sr or immediate to sr move to sr (68010 only) reset move from sr (68010 only) rte movec (68010 only) stop moves (68010 only) exception processing for privilege violations is nearly identical to that for illegal instructions. after the instruction is fetched and decoded and the processor determines that a privilege violation is being attempted, the processor starts exception processing. the status register is copied; the supervisor mode is entered; and tracing is turned off. the vector number is generated to reference the privilege violation vector, and the current program counter and the copy of the status register are saved on the supervisor stack. if the processor is an MC68010, the format/offset word is also saved. the saved value of the program counter is the address of the first word of the instruction causing the privilege violation. finally, instruction execution commences at the address in the privilege violation exception vector. 6.3.8 tracing to aid in program development, the m68000 family includes a facility to allow tracing following each instruction. when tracing is enabled, an exception is forced after each instruction is executed. thus, a debugging program can monitor the execution of the program under test. the trace facility is controlled by the t bit in the supervisor portion of the status register. if the t bit is cleared (off), tracing is disabled and instruction execution proceeds from instruction to instruction as normal. if the t bit is set (on) at the beginning of the execution of an instruction, a trace exception is generated after the instruction is completed. if the instruction is not executed because an interrupt is taken or because the instruction is illegal or privileged, the trace exception does not occur. the trace exception also does not occur if the instruction is aborted by a reset, bus error, or address error exception. if the instruction is executed and an interrupt is pending on completion, the trace exception is processed before the interrupt exception. during the execution of the instruction, if an exception is forced by that instruction, the exception processing for the instruction exception occurs before that of the trace exception. as an extreme illustration of these rules, consider the arrival of an interrupt during the execution of a trap instruction while tracing is enabled. first, the trap exception is processed, then the trace exception, and finally the interrupt exception. instruction execution resumes in the interrupt handler routine.
6- 16 m68000 8-/16-/32-bit microprocessors user's manual motorola after the execution of the instruction is complete and before the start of the next instruction, exception processing for a trace begins. a copy is made of the status register. the transition to supervisor mode is made, and the t bit of the status register is turned off, disabling further tracing. the vector number is generated to reference the trace exception vector, and the current program counter and the copy of the status register are saved on the supervisor stack. on the MC68010, the format/offset word is also saved on the supervisor stack. the saved value of the program counter is the address of the next instruction. instruction execution commences at the address contained in the trace exception vector. 6.3.9 bus error a bus error exception occurs when the external logic requests that a bus error be processed by an exception. the current bus cycle is aborted. the current processor activity, whether instruction or exception processing, is terminated, and the processor immediately begins exception processing. the bus error facility is identical on the all processors; however, the stack frame produced on the MC68010 contains more information. the larger stack frame supports instruction continuation, which supports virtual memory on the MC68010 processor. 6.3.9.1 bus error . exception processing for a bus error follows the usual sequence of steps. the status register is copied, the supervisor mode is entered, and tracing is turned off. the vector number is generated to refer to the bus error vector. since the processor is fetching the instruction or an operand when the error occurs, the context of the processor is more detailed. to save more of this context, additional information is saved on the supervisor stack. the program counter and the copy of the status register are saved. the value saved for the program counter is advanced 2?0 bytes beyond the address of the first word of the instruction that made the reference causing the bus error. if the bus error occurred during the fetch of the next instruction, the saved program counter has a value in the vicinity of the current instruction, even if the current instruction is a branch, a jump, or a return instruction. in addition to the usual information, the processor saves its internal copy of the first word of the instruction being processed and the address being accessed by the aborted bus cycle. specific information about the access is also saved: type of access (read or write), processor activity (processing an instruction), and function code outputs when the bus error occurred. the processor is processing an instruction if it is in the normal state or processing a group 2 exception; the processor is not processing an instruction if it is processing a group 0 or a group 1 exception. figure 6-7 illustrates how this information is organized on the supervisor stack. if a bus error occurs during the last step of exception processing, while either reading the exception vector or fetching the instruction, the value of the program counter is the address of the exception vector. although this information is not generally sufficient to effect full recovery from the bus error, it does allow software diagnosis. finally, the processor commences instruction processing at the address in the vector. it is the responsibility of the error handler routine to clean up the stack and determine where to continue execution. if a bus error occurs during the exception processing for a bus error, an address error, or a reset, the processor halts and all processing ceases. this halt simplifies the detection of a catastrophic system failure, since the processor removes itself from the system to
motorola m68000 8-/16-/32-bit microprocessors user? manual 6- 17 protect memory contents from erroneous accesses. only an external reset operation can restart a halted processor. low high lower address r/w access address instruction register status register 5 4 3 2 1 0 15 14 13 12 11 10 9 8 7 6 function code i/n program counter low high r/w (read/write): write=0, read=1. i/n (instruction/not): instruction=0, not=1 figure 6-7. supervisor stack order for bus or address error exception 6.3.9.2 bus error (MC68010) . exception processing for a bus error follows a slightly different sequence than the sequence for group 1 and 2 exceptions. in addition to the four steps executed during exception processing for all other exceptions, 22 words of additional information are placed on the stack. this additional information describes the internal state of the processor at the time of the bus error and is reloaded by the rte instruction to continue the instruction that caused the error. figure 6-8 shows the order of the stacked information.
6- 18 m68000 8-/16-/32-bit microprocessors user's manual motorola . program counter (low) program counter (high) 0 status register vector offset 1000 special status word fault address (high) 151413121110987654321 fault address (low) unused, reserved data output buffer data input buffer version number instruction input buffer unused, reserved unused, reserved internal information, 16 words sp note: the stack pointer is decremented by 29 words, although only 26 words of information are actually written to memory. the three additional words are reserved for future use by motorola. figure 6-8. exception stack order (bus and address error) the value of the saved program counter does not necessarily point to the instruction that was executing when the bus error occurred, but may be advanced by as many as five words. this incrementing is caused by the prefetch mechanism on the MC68010 that always fetches a new instruction word as each previously fetched instruction word is used. however, enough information is placed on the stack for the bus error exception handler to determine why the bus fault occurred. this additional information includes the address being accessed, the function codes for the access, whether it was a read or a write access, and the internal register included in the transfer. the fault address can be used by an operating system to determine what virtual memory location is needed so that the requested data can be brought into physical memory. the rte instruction is used to reload the internal state of the processor at the time of the fault. the faulted bus cycle is then rerun, and the suspended instruction is completed. if the faulted bus cycle is a read- modify-write, the entire cycle is rerun, whether the fault occurred during the read or the write operation. an alternate method of handling a bus error is to complete the faulted access in software. using this method requires the special status word, the instruction input buffer, the data input buffer, and the data output buffer image. the format of the special status word is
motorola m68000 8-/16-/32-bit microprocessors user? manual 6- 19 shown in figure 6-9. if the bus cycle is a read, the data at the fault address should be written to the images of the data input buffer, instruction input buffer, or both according to the data fetch (df) and instruction fetch (if) bits. * in addition, for read-modify-write cycles, the status register image must be properly set to reflect the read data if the fault occurred during the read portion of the cycle and the write operation (i.e., setting the most significant bit of the memory location) must also be performed. these operations are required because the entire read-modify-write cycle is assumed to have been completed by software. once the cycle has been completed by software, the rerun (rr) bit in the special status word is set to indicate to the processor that it should not rerun the cycle when the rte instruction is executed. if the rr bit is set when an rte instruction executes, the MC68010 reads all the information from the stack, as usual. 15 14 13 12 11 10 9 8 7 3 2 0 rr * i f df rm hb by rw * fc2?c0 rr rerun flag; 0=processor rerun (default), 1=software rerun if instruction fetch to the instruction input buffer df data fetch to the data input buffer rm read-modify-write cycle hb high-byte transfer from the data output buffer or to the data input buffer by byte-transfer flag; hb selects the high or low byte of the transfer register. if by is clear, the transfer is word. rw read/write flag; 0=write, 1=read fc the function code used during the faulted access * these bits are reserved for future use by motorola and will be zero when written by the MC68010. figure 6-9. special status word format 6.3.10 address error an address error exception occurs when the processor attempts to access a word or long- word operand or an instruction at an odd address. an address error is similar to an internally generated bus error. the bus cycle is aborted, and the processor ceases current processing and begins exception processing. the exception processing sequence is the same as that for a bus error, including the information to be stacked, except that the vector number refers to the address error vector. likewise, if an address error occurs during the exception processing for a bus error, address error, or reset, the processor is halted. on the MC68010, the address error exception stacks the same information stacked by a bus error exception. therefore, the rte instruction can be used to continue execution of the suspended instruction. however, if the rr flag is not set, the fault address is used when the cycle is retried, and another address error exception occurs. therefore, the user must be certain that the proper corrections have been made to the stack image and user registers before attempting to continue the instruction. with proper software handling, the address error exception handler could emulate word or long-word accesses to odd addresses if desired. * if the faulted access was a byte operation, the data should be moved from or to the least significant byte of the data output or input buffer images, unless the high-byte transfer (hb) bit is set. this condition occurs if a movep instruction caused the fault during transfer of bits 8?5 of a word or long word or bits 24?1 of a long word.
6- 20 m68000 8-/16-/32-bit microprocessors user's manual motorola 6.4 return from exception (MC68010) in addition to returning from any exception handler routine on the MC68010, the rte instruction resumes the execution of a suspended instruction by returning to the normal processing state after restoring all of the temporary register and control information stored during a bus error. for the rte instruction to execute properly, the stack must contain valid and accessible data. the rte instruction checks for data validity in two ways. first, the format/offset word is checked for a valid stack format code. second, if the format code indicates the long stack format, the validity of the long stack data is checked as it is loaded into the processor. in addition, the data is checked for accessibility when the processor starts reading the long data. because of these checks, the rte instruction executes as follows: 1. determine the stack format. this step is the same for any stack format and consists of reading the status register, program counter, and format/offset word. if the format code indicates a short stack format, execution continues at the new program counter address. if the format code is not an MC68010-defined stack format code, exception processing starts for a format error. 2. determine data validity. for a long-stack format, the MC68010 begins to read the remaining stack data, checking for validity of the data. the only word checked for validity is the first of the 16 internal information words (sp + 26) shown in figure 5-8. this word contains a processor version number (in bits 10?3) and proprietary internal information that must match the version number of the MC68010 attempting to read the data. this validity check is used to ensure that the data is properly interpreted by the rte instruction. if the version number is incorrect for this processor, the rte instruction is aborted and exception processing begins for a format error exception. since the stack pointer is not updated until the rte instruction has successfully read all the stack data, a format error occurring at this point does not stack new data over the previous bus error stack information. 3. determine data accessibility. if the long-stack data is valid, the MC68010 performs a read from the last word (sp + 56) of the long stack to determine data accessibility. if this read is terminated normally, the processor assumes that the remaining words on the stack frame are also accessible. if a bus error is signaled before or during this read, a bus error exception is taken. after this read, the processor must be able to load the remaining data without receiving a bus error; therefore, if a bus error occurs on any of the remaining stack reads, the error becomes a double bus fault, and the MC68010 enters the halted state.
motorola m68000 8-/16-/32-bit microprocessors user's manual 7- 1 section 7 8-bit instruction execution times this section contains listings of the instruction execution times in terms of external clock (clk) periods for the mc68008 and mc68hc001/mc68ec000 in 8-bit mode. in this data, it is assumed that both memory read and write cycles consist of four clock periods. a longer memory cycle causes the generation of wait states that must be added to the total instruction times. the number of bus read and write cycles for each instruction is also included with the timing data. this data is shown as n(r/w) where: n is the total number of clock periods r is the number of read cycles w is the number of write cycles for example, a timing number shown as 18(3/1) means that 18 clock periods are required to execute the instruction. of the 18 clock periods, 12 are used for the three read cycles (four periods per cycle). four additional clock periods are used for the single write cycle, for a total of 16 clock periods. the bus is idle for two clock periods during which the processor completes the internal operations required for the instruction. note the total number of clock periods (n) includes instruction fetch and all applicable operand fetches and stores. 7.1 operand effective address calculation times table 7-1 lists the numbers of clock periods required to compute the effective addresses for instructions. the totals include fetching any extension words, computing the address, and fetching the memory operand. the total number of clock periods, the number of read cycles, and the number of write cycles (zero for all effective address calculations) are shown in the previously described format.
7- 2 m68000 8-/16-/32-bit microprocessors user's manual motorola table 7-1. effective address calculation times addressing mode byte word long dn an register data register direct address register direct 0 (0/0) 0 (0/0) 0 (0/0) 0 (0/0) 0 (0/0) 0 (0/0) (an) (an)+ memory address register indirect address register indirect with postincrement 4 (1/0) 4 (1/0) 8 (2/0) 8 (2/0) 16 (4/0) 16 (4/0) ?an) (d 16 , an) address register indirect with predecrement address register indirect with displacement 6 (1/0) 12 (3/0) 10 (2/0) 16 (4/0) 18 (4/0) 24 (6/0) (d 8 , an, xn)* (xxx).w address register indirect with index absolute short 14 (3/0) 12 (3/0) 18 (4/0) 16 (4/0) 26 (6/0) 24 (6/0) (xxx).l (d 16 , pc) absolute long program counter indirect with displacement 20 (5/0) 12 (3/0) 24 (6/0) 16 (3/0) 32 (8/0) 24 (6/0) (d 8 , pc, xn)* # program counter indirect with index immediate 14 (3/0) 8 (2/0) 18 (4/0) 8 (2/0) 26 (6/0) 16 (4/0) *the size of the index register (xn) does not affect execution time. 7.2 move instruction execution times tables 7-2, 7-3, and 7-4 list the numbers of clock periods for the move instructions. the totals include instruction fetch, operand reads, and operand writes. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. table 7-2. move byte instruction execution times destination source dn an (an) (an)+ ?an) (d 16 , an) (d 8 , an, xn)* (xxx).w (xxx).l dn an (an) 8 (2/0) 8 (2/0) 12 (3/0) 8 (2/0) 8 (2/0) 12 (3/0) 12 (2/1) 12 (2/1) 16 (3/1) 12 (2/1) 12 (2/1) 16 (3/1) 12 (2/1) 12 (2/1) 16 (3/1) 20 (4/1) 20 (4/1) 24 (5/1) 22 (4/1) 22 (4/1) 26 (5/1) 20 (4/1) 20 (4/1) 24 (5/1) 28 (6/1) 28 (6/1) 32 (7/1) (an)+ ?an) (d 16 , an) 12 (3/0) 14 (3/0) 20 (5/0) 12 (3/0) 14 (3/0) 20 (5/0) 16 (3/1) 18 (3/1) 24 (5/1) 16 (3/1) 18 (3/1) 24 (5/1) 16 (3/1) 18 (3/1) 24 (5/1) 24 (5/1) 26 (5/1) 32 (7/1) 26 (5/1) 28 (5/1) 34 (7/1) 24 (5/1) 26 (5/1) 32 (7/1) 32 (7/1) 34 (7/1) 40 (9/1) (d 8 , an, xn)* (xxx).w (xxx).l 22 (5/0) 20 (5/0) 28 (7/0) 22 (5/0) 20 (5/0) 28 (7/0) 26 (5/1) 24 (5/1) 32 (7/1) 26 (5/1) 24 (5/1) 32 (7/1) 26 (5/1) 24 (5/1) 32 (7/1) 34 (7/1) 32 (7/1) 40 (9/1) 36 (7/1) 34 (7/1) 42 (9/1) 34 (7/1) 32 (7/1) 40 (9/1) 42 (9/1) 40 (9/1) 48 (11/1) (d 16 , pc) (d 8 , pc, xn)* # 20 (5/0) 22 (5/0) 16 (4/0) 20 (5/0) 22 (5/0) 16 (4/0) 24 (5/1) 26 (5/1) 20 (4/1) 24 (5/1) 26 (5/1) 20 (4/1) 24 (5/1) 26 (5/1) 20 (4/1) 32 (7/1) 34 (7/1) 28 (6/1) 34 (7/1) 36 (7/1) 30 (6/1) 32 (7/1) 34 (7/1) 28 (6/1) 40 (9/1) 42 (9/1) 36 (8/1) *the size of the index register (xn) does not affect execution time.
motorola m68000 8-/16-/32-bit microprocessors user's manual 7- 3 table 7-3. move word instruction execution times destination source dn an (an) (an)+ ?an) (d 16 , an) (d 8 , an, xn)* (xxx).w (xxx).l dn an (an) 8 (2/0) 8 (2/0) 16 (4/0) 8 (2/0) 8 (2/0) 16 (4/0) 16 (2/2) 16 (2/2) 24 (4/2) 16 (2/2) 16 (2/2) 24 (4/2) 16 (2/2) 16 (2/2) 24 (4/2) 24 (4/2) 24 (4/2) 32 (6/2) 26 (4/2) 26 (4/2) 34 (6/2) 24 (4/2) 24 (4/2) 32 (6/2) 32 (6/2) 32 (6/2) 40 (8/2) (an)+ ?an) (d 16 , an) 16 (4/0) 18 (4/0) 24 (6/0) 16 (4/0) 18 (4/0) 24 (6/0) 24 (4/2) 26 (4/2) 32 (6/2) 24 (4/2) 26 (4/2) 32 (6/2) 24 (4/2) 26 (4/2) 32 (6/2) 32 (6/2) 34 (6/2) 40 (8/2) 34 (6/2) 32 (6/2) 42 (8/2) 32 (6/2) 34 (6/2) 40 (8/2) 40 (8/2) 42 (8/2) 48 (10/2) (d 8 , an, xn)* (xxx).w (xxx).l 26 (6/0) 24 (6/0) 32 (8/0) 26 (6/0) 24 (6/0) 32 (8/0) 34 (6/2) 32 (6/2) 40 (8/2) 34 (6/2) 32 (6/2) 40 (8/2) 34 (6/2) 32 (6/2) 40 (8/2) 42 (8/2) 40 (8/2) 48 (10/2) 44 (8/2) 42 (8/2) 50 (10/2) 42 (8/2) 40 (8/2) 48 (10/2) 50 (10/2) 48 (10/2) 56 (12/2) (d 16 , pc) (d 8 , pc, xn)* # 24 (6/0) 26 (6/0) 16 (4/0) 24 (6/0) 26 (6/0) 16 (4/0) 32 (6/2) 34 (6/2) 24 (4/2) 32 (6/2) 34 (6/2) 24 (4/2) 32 (6/2) 34 (6/2) 24 (4/2) 40 (8/2) 42 (8/2) 32 (6/2) 42 (8/2) 44 (8/2) 34 (6/2) 40 (8/2) 42 (8/2) 32 (6/2) 48 (10/2) 50 (10/2) 40 (8/2) *the size of the index register (xn) does not affect execution time. table 7-4. move long instruction execution times destination source dn an (an) (an)+ ?an) (d 16 , an) (d 8 , an, xn)* (xxx).w (xxx).l dn an (an) 8 (2/0) 8 (2/0) 24 (6/0) 8 (2/0) 8 (2/0) 24 (6/0) 24 (2/4) 24 (2/4) 40 (6/4) 24 (2/4) 24 (2/4) 40 (6/4) 24 (2/4) 24 (2/4) 40 (6/4) 32 (4/4) 32 (4/4) 48 (8/4) 34 (4/4) 34 (4/4) 50 (8/4) 32 (4/4) 32 (4/4) 48 (8/4) 40 (6/4) 40 (6/4) 56 (10/4) (an)+ ?an) (d 16 , an) 24 (6/0) 26 (6/0) 32 (8/0) 24 (6/0) 26 (6/0) 32 (8/0) 40 (6/4) 42 (6/4) 48 (8/4) 40 (6/4) 42 (6/4) 48 (8/4) 40 (6/4) 42 (6/4) 48 (8/4) 48 (8/4) 50 (8/4) 56 (10/4) 50 (8/4) 52 (8/4) 58 (10/4) 48 (8/4) 50 (8/4) 56 (10/4) 56 (10/4) 58 (10/4) 64 (12/4) (d 8 , an, xn)* (xxx).w (xxx).l 34 (8/0) 32 (8/0) 40 (10/0) 34 (8/0) 32 (8/0) 40 (10/0) 50 (8/4) 48 (8/4) 56 (10/4) 50 (8/4) 48 (8/4) 56 (10/4) 50 (8/4) 48 (8/4) 56 (10/4) 58 (10/4) 56 (10/4) 64 (12/4) 60 (10/4) 58 (10/4) 66 (12/4) 58 (10/4) 56 (10/4) 64 (12/4) 66 (12/4) 64 (12/4) 72 (14/4) (d 16 , pc) (d 8 , pc, xn)* # 32 (8/0) 34 (8/0) 24 (6/0) 32 (8/0) 34 (8/0) 24 (6/0) 48 (8/4) 50 (8/4) 40 (6/4) 48 (8/4) 50 (8/4) 40 (6/4) 48 (8/4) 50 (8/4) 40 (6/4) 56 (10/4) 58 (10/4) 48 (8/4) 58 (10/4) 60 (10/4) 50 (8/4) 56 (10/4) 58 (10/4) 48 (8/4) 64 (12/4) 66 (12/4) 56 (10/4) *the size of the index register (xn) does not affect execution time. 7.3 standard instruction execution times the numbers of clock periods shown in table 7-5 indicate the times required to perform the operations, store the results, and read the next instruction. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+).
7- 4 m68000 8-/16-/32-bit microprocessors user's manual motorola in table 7-5, the following notation applies: an address register operand dn data register operand ea an operand specified by an effective address m memory effective address operand table 7-5. standard instruction execution times instruction size op, an op, dn op dn, add/adda byte word long 12 (2/0)+ 10 (2/0)+** 8 (2/0)+ 8 (2/0)+ 10 (2/0)+** 12 (2/1)+ 16 (2/2)+ 24 (2/4)+ and byte word long 8 (2/0)+ 8 (2/0)+ 10 (2/0)+** 12 (2/1)+ 16 (2/2)+ 24 (2/4)+ cmp/cmpa byte word long 10 (2/0)+ 10 (2/0)+ 8 (2/0)+ 8 (2/0)+ 10 (2/0)+ divs divu 162 (2/0)+* 144 (2/0)+* eor byte, word, long 8 (2/0)+*** 8 (2/0)+*** 12 (2/0)+*** 12 (2/1)+ 16 (2/2)+ 24 (2/4)+ muls mulu 74 (2/0)+* 74 (2/0)+* or byte, word long 8 (2/0)+ 8 (2/0)+ 10 (2/0)+** 12 (2/1)+ 16 (2/2)+ 24 (2/4)+ sub byte, word long 12 (2/0)+ 10 (2/0)+** 8 (2/0)+ 8 (2/0)+ 10 (2/0)+** 12 (2/1)+ 16 (2/2)+ 24 (2/4)+ + add effective address calculation time. * indicates maximum base value added to word effective address time ** the base time of 10 clock periods is increased to 12 if the effective address mode is register direct or immediate (effective address time should also be added). *** only available effective address mode is data register direct. divs, divu the divide algorithm used by the mc68008 provides less than 10% difference between the best- and worst-case timings. muls, mulu the multiply algorithm requires 42+2n clocks where n is defined as: muls: n = tag the with a zero as the msb; n is the resultant number of 10 or 01 patterns in the 17-bit source; i.e., worst case happens when the source is $5555. mulu: n = the number of ones in the 7.4 immediate instruction execution times the numbers of clock periods shown in table 7-6 include the times to fetch immediate operands, perform the operations, store the results, and read the next operation. the total number of clock periods, the number of read cycles, and the number of write cycles are
motorola m68000 8-/16-/32-bit microprocessors user's manual 7- 5 shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+). in table 7-6, the following notation applies: # immediate operand dn data register operand an address register operand m memory operand table 7-6. immediate instruction execution times instruction size op #, dn op #, an op #, m addi byte word long 16 (4/0) 16 (4/0) 28 (6/0) 20 (4/1)+ 24 (4/2)+ 40 (6/4)+ addq byte word long 8 (2/0) 8 (2/0) 12 (2/0) 12 (2/0) 12 (2/0) 12 (2/1)+ 16 (2/2)+ 24 (2/4)+ andi byte word long 16 (4/0) 16 (4/0) 28 (6/0) 20 (4/1)+ 24 (4/2)+ 40 (6/4)+ cmpi byte word long 16 (4/0) 16 (4/0) 26 (6/0) 16 (4/0) 16 (4/0) 24 (6/0) eori byte word long 16 (4/0) 16 (4/0) 28 (6/0) 20 (4/1)+ 24 (4/2)+ 40 (6/4)+ moveq long 8 (2/0) ori byte word long 16 (4/0) 16 (4/0) 28 (6/0) 20 (4/1)+ 24 (4/2)+ 40 (6/4)+ subi byte word long 16 (4/0) 16 (4/0) 28 (6/0) 12 (2/1)+ 16 (2/2)+ 24 (2/4)+ subq byte word long 8 (2/0) 8 (2/0) 12 (2/0) 12 (2/0) 12 (2/0) 20 (4/1)+ 24 (4/2)+ 40 (6/4)+ +add effective address calculation time. 7.5 single operand instruction execution times table 7-7 lists the timing data for the single operand instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+).
7- 6 m68000 8-/16-/32-bit microprocessors user's manual motorola table 7-7. single operand instruction execution times instruction size register memory clr byte word long 8 (2/0) 8 (2/0) 10 (2/0) 12 (2/1)+ 16 (2/2)+ 24 (2/4)+ nbcd byte 10 (2/0) 12 (2/1)+ neg byte word long 8 (2/0) 8 (2/0) 10 (2/0) 12 (2/1)+ 16 (2/2)+ 24 (2/4)+ negx byte word long 8 (2/0) 8 (2/0) 10 (2/0) 12 (2/1)+ 16 (2/2)+ 24 (2/4)+ not byte word long 8 (2/0) 8 (2/0) 10 (2/0) 12 (2/1)+ 16 (2/2)+ 24 (2/4)+ scc byte, false byte, true 8 (2/0) 10 (2/0) 12 (2/1)+ 12 (2/1)+ tas byte 8 (2/0) 14 (2/1)+ tst byte word long 8 (2/0) 8 (2/0) 8 (2/0) 8 (2/0)+ 8 (2/0)+ 8 (2/0)+ +add effective address calculation time. 7.6 shift/rotate instruction execution times table 7-8 lists the timing data for the shift and rotate instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+). table 7-8. shift/rotate instruction execution times instruction size register memory asr, asl byte word long 10+2n (2/0) 10+2n (2/0) 12+n2 (2/0) 16 (2/2)+ lsr, lsl byte word long 10+2n (2/0) 10+2n (2/0) 12+n2 (2/0) 16 (2/2)+ ror, rol byte word long 10+2n (2/0) 10+2n (2/0) 12+n2 (2/0) 16 (2/2)+ roxr, roxl byte word long 10+2n (2/0) 10+2n (2/0) 12+n2 (2/0) 16 (2/2)+ +add effective address calculation time for word operands. n is the shift count.
motorola m68000 8-/16-/32-bit microprocessors user's manual 7- 7 7.7 bit manipulation instruction execution times table 7-9 lists the timing data for the bit manipulation instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+). table 7-9. bit manipulation instruction execution times dynamic static instruction size register memory register memory bchg byte long 12 (2/0)* 12 (2/1)+ 20 (4/0)* 20 (4/1)+ bclr byte long 14 (2/0)* 12 (2/1)+ 22 (4/0)* 20 (4/1)+ bset byte long 12 (2/0)* 12 (2/1)+ 20 (4/0)* 20 (4/1)+ btst byte long 10 (2/0) 8 (2/0)+ 18 (4/0) 16 (4/0)+ +add effective address calculation time. * indicates maximum value; data addressing mode only. 7.8 conditional instruction execution times table 7-10 lists the timing data for the conditional instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+). table 7-10. conditional instruction execution times instruction displacement trap or branch taken trap or branch not taken bcc byte word 18 (4/0) 18 (4/0) 12 (2/0) 20 (4/0) bra byte word 18 (4/0) 18 (4/0) bsr byte word 34 (4/4) 34 (4/4) dbcc cc true cc false 18 (4/0) 20 (4/0) 26 (6/0) chk 68 (8/6)+* 14 (2/0) trap 62 (8/6) trapv 66 (10/6) 8 (2/0) +add effective address calculation time for word operand. * indicates maximum base value.
7- 8 m68000 8-/16-/32-bit microprocessors user's manual motorola 7.9 jmp, jsr, lea, pea, and movem instruction execution times table 7-11 lists the timing data for the jump (jmp), jump to subroutine (jsr), load effective address (lea), push effective address (pea), and move multiple registers (movem) instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. table 7-11. jmp, jsr, lea, pea, and movem instruction execution times instruction size (an) (an)+ ?an) (d 16 ,an) (d 8 ,an,xn)+ (xxx).w (xxx).l (d 16 pc) (d 8 , pc, xn)* jmp 16 (4/0) 18 (4/0) 22 (4/0) 18 (4/0) 24 (6/0) 18 (4/0) 22 (4/0) jsr 32 (4/4) 34 (4/4) 38 (4/4) 34 (4/4) 40 (6/4) 34 (4/4) 32 (4/4) lea 8 (2/0) 16 (4/0) 20 (4/0) 16 (4/0) 24 (6/0) 16 (4/0) 20 (4/0) pea 24 (2/4) 32 (4/4) 36 (4/4) 32 (4/4) 40 (6/4) 32 (4/4) 36 (4/4) movem m r word 24+8n (6+2n/0) 24+8n (6+2n/0) 32+8n (8+2n/0) 34+8n (8+2n/0) 32+8n (10+n/0) 40+8n (10+2n/0) 32+8n (8+2n/0) 34+8n (8+2n/0) long 24+16n (6+4n/0) 24+16n (6+4n/0) 32+16n (8+4n/0) 34+16n (8+4n/0) 32+16n (8+4n/0) 40+16n (8+4n/0) 32+16n (8+4n/0) 34+16n (8+4n/0) movem r m word 16+8n (4/2n) 16+8n (4/2n) 24+8n (6/2n) 26+8n (6/2n) 24+8n (6/2n) 32+8n (8/2n) long 16+16n (4/4n) 16+16n (4/4n) 24+16n (6/4n) 26+16n 24+16n (8/4n) 32+16n (6/4n) n is the number of registers to move. *the size of the index register (xn) does not affect the instruction's execution time. 7.10 multiprecision instruction execution times table 7-12 lists the timing data for multiprecision instructions. the numbers of clock periods include the times to fetch both operands, perform the operations, store the results, and read the next instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the following notation applies in table 7-12: dn data register operand m memory operand
motorola m68000 8-/16-/32-bit microprocessors user's manual 7- 9 table 7-12. multiprecision instruction execution times instruction size op dn, dn op m, m addx byte word long 8 (2/0) 8 (2/0) 12 (2/0) 22 (4/1) 50 (6/2) 58 (10/4) cmpm byte, word long 16 (4/0) 24 (6/0) 40 (10/0) subx byte, \ word long 8 (2/0) 8 (2/0) 12 (2/0) 22 (4/1) 50 (6/2) 58 (10/4) abcd byte 10 (2/0) 20 (4/1) sbcd byte 10 (2/0) 20 (4/1) 7.11 miscellaneous instruction execution times tables 7-13 and 7-14 list the timing data for miscellaneous instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+).
7- 10 m68000 8-/16-/32-bit microprocessors user's manual motorola table 7-13. miscellaneous instruction execution times instruction register memory andi to ccr 32 (6/0) andi to sr 32 (6/0) eori to ccr 32 (6/0) eori to sr 32 (6/0) exg 10 (2/0) ext 8 (2/0) link 32 (4/4) move to ccr 18 (4/0) 18 (4/0)+ move to sr 18 (4/0) 18 (4/0)+ move from sr 10 (2/0) 16 (2/2)+ move to usp 8 (2/0) move from usp 8 (2/0) nop 8 (2/0) ori to ccr 32 (6/0) ori to sr 32 (6/0) reset 136 (2/0) rte 40 (10/0) rtr 40 (10/0) rts 32 (8/0) stop 4 (0/0) swap 8 (2/0) trapv (no trap) 8 (2/0) unlk 24 (6/0) +add effective address calculation time for word operand. table 7-14. move peripheral instruction execution times instruction size register memory memory register movep word 24 (4/2) 24 (6/0) long 32 (4/4) 32 (8/0) +add effective address calculation time. 7.12 exception processing execution times table 7-15 lists the timing data for exception processing. the numbers of clock periods include the times for all stacking, the vector fetch, and the fetch of the first instruction of the handler routine. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock
motorola m68000 8-/16-/32-bit microprocessors user's manual 7- 11 periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+). table 7-15. exception processing execution times exception periods address error 94 (8/14) bus error 94 (8/14) chk instruction 68 (8/6)+ divide by zero 66 (8/6)+ interrupt 72 (9/6)* illegal instruction 62 (8/6) privilege violation 62 (8/6) reset ** 64 (12/0) trace 62 (8/6) trap instruction 62 (8/6) trapv instruction 66 (10/6) + add effective address calculation time. ** indicates the time from when reset and halt are first sampled as negated to when instruction execution starts.
motorola mc68000 8-/16-/32-microprocessors user? manual 8- 1 section 8 16-bit instruction execution times this section contains listings of the instruction execution times in terms of external clock (clk) periods for the mc68000, mc68hc000, mc68hc001, and the mc68ec000 in 16- bit mode. in this data, it is assumed that both memory read and write cycles consist of four clock periods. a longer memory cycle causes the generation of wait states that must be added to the total instruction times. the number of bus read and write cycles for each instruction is also included with the timing data. this data is shown as n(r/w) where: n is the total number of clock periods r is the number of read cycles w is the number of write cycles for example, a timing number shown as 18(3/1) means that the total number of clock periods is 18. of the 18 clock periods, 12 are used for the three read cycles (four periods per cycle). four additional clock periods are used for the single write cycle, for a total of 16 clock periods. the bus is idle for two clock periods during which the processor completes the internal operations required for the instruction. note the total number of clock periods (n) includes instruction fetch and all applicable operand fetches and stores. 8.1 operand effective address calculation times table 8-1 lists the numbers of clock periods required to compute the effective addresses for instructions. the total includes fetching any extension words, computing the address, and fetching the memory operand. the total number of clock periods, the number of read cycles, and the number of write cycles (zero for all effective address calculations) are shown in the previously described format.
8- 2 mc68000 8-/16-/32-microprocessors uiser's manual motorola table 8-1. effective address calculation times addressing mode byte, word long dn an register data register direct address register direct 0 (0/0) 0 (0/0) 0 (0/0) 0 (0/0) (an) (an)+ memory address register indirect address register indirect with postincrement 4 (1/0) 4 (1/0) 8 (2/0) 8 (2/0) ?an) (d 16 , an) address register indirect with predecrement address register indirect with displacement 6 (1/0) 8 (2/0) 10 (2/0) 12 (3/0) (d 8 , an, xn)* (xxx).w address register indirect with index absolute short 10 (2/0) 8 (2/0) 14 (3/0) 12 (3/0) (xxx).l (d 8 , pc) absolute long program counter indirect with displacement 12 (3/0) 8 (2/0) 16 (4/0) 12 (3/0) (d 16 , pc, xn)* # program counter indirect with index immediate 10 (2/0) 4 (1/0) 14 (3/0) 8 (2/0) *the size of the index register (xn) does not affect execution time. 8.2 move instruction execution times tables 8-2 and 8-3 list the numbers of clock periods for the move instructions. the totals include instruction fetch, operand reads, and operand writes. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. table 8-2. move byte and word instruction execution times destination source dn an (an) (an)+ ?an) (d 16 , an) (d 8 , an, xn)* (xxx).w (xxx).l dn an (an) 4 (1/0) 4 (1/0) 8 (2/0) 4 (1/0) 4 (1/0) 8 (2/0) 8 (1/1) 8 (1/1) 12 (2/1) 8 (1/1) 8 (1/1) 12 (2/1) 8 (1/1) 8 (1/1) 12 (2/1) 12 (2/1) 12 (2/1) 16 (3/1) 14 (2/1) 14 (2/1) 18 (3/1) 12 (2/1) 12 (2/1) 16 (3/1) 16 (3/1) 16 (3/1) 20 (4/1) (an)+ ?an) (d 16 , an) 8 (2/0) 10 (2/0) 12 (3/0) 8 (2/0) 10 (2/0) 12 (3/0) 12 (2/1) 14 (2/1) 16 (3/1) 12 (2/1) 14 (2/1) 16 (3/1) 12 (2/1) 14 (2/1) 16 (3/1) 16 (3/1) 18 (3/1) 20 (4/1) 18 (3/1) 20 (3/1) 22 (4/1) 16 (3/1) 18 (3/1) 20 (4/1) 20 (4/1) 22 (4/1) 24 (5/1) (d 8 , an, xn)* (xxx).w (xxx).l 14 (3/0) 12 (3/0) 16 (4/0) 14 (3/0) 12 (3/0) 16 (4/0) 18 (3/1) 16 (3/1) 20 (4/1) 18 (3/1) 16 (3/1) 20 (4/1) 18 (3/1) 16 (3/1) 20 (4/1) 22 (4/1) 20 (4/1) 24 (5/1) 24 (4/1) 22 (4/1) 26 (5/1) 22 (4/1) 20 (4/1) 24 (5/1) 26 (5/1) 24 (5/1) 28 (6/1) (d 16 , pc) (d 8 , pc, xn)* # 12 (3/0) 14 (3/0) 8 (2/0) 12 (3/0) 14 (3/0) 8 (2/0) 16 (3/1) 18 (3/1) 12 (2/1) 16 (3/1) 18 (3/1) 12 (2/1) 16 (3/1) 18 (3/1) 12 (2/1) 20 (4/1) 22 (4/1) 16 (3/1) 22 (4/1) 24 (4/1) 18 (3/1) 20 (4/1) 22 (4/1) 16 (3/1) 24 (5/1) 26 (5/1) 20 (4/1) *the size of the index register (xn) does not affect execution time.
motorola mc68000 8-/16-/32-microprocessors user? manual 8- 3 table 8-3. move long instruction execution times destination source dn an (an) (an)+ ?an) (d 16 , an) (d 8 , an, xn)* (xxx).w (xxx).l dn an (an) 4 (1/0) 4 (1/0) 12 (3/0) 4 (1/0) 4 (1/0) 12 (3/0) 12 (1/2) 12 (1/2) 20 (3/2) 12 (1/2) 12 (1/2) 20 (3/2) 12 (1/2) 12 (1/2) 20 (3/2) 16 (2/2) 16 (2/2) 24 (4/2) 18 (2/2) 18 (2/2) 26 (4/2) 16 (2/2) 16 (2/2) 24 (4/2) 20 (3/2) 20 (3/2) 28 (5/2) (an)+ ?an) (d 16 , an) 12 (3/0) 14 (3/0) 16 (4/0) 12 (3/0) 14 (3/0) 16 (4/0) 20 (3/2) 22 (3/2) 24 (4/2) 20 (3/2) 22 (3/2) 24 (4/2) 20 (3/2) 22 (3/2) 24 (4/2) 24 (4/2) 26 (4/2) 28 (5/2) 26 (4/2) 28 (4/2) 30 (5/2) 24 (4/2) 26 (4/2) 28 (5/2) 28 (5/2) 30 (5/2) 32 (6/2) (d 8 , an, xn)* (xxx).w (xxx).l 18 (4/0) 16 (4/0) 20 (5/0) 18 (4/0) 16 (4/0) 20 (5/0) 26 (4/2) 24 (4/2) 28 (5/2) 26 (4/2) 24 (4/2) 28 (5/2) 26 (4/2) 24 (4/2) 28 (5/2) 30 (5/2) 28 (5/2) 32 (6/2) 32 (5/2) 30 (5/2) 34 (6/2) 30 (5/2) 28 (5/2) 32 (6/2) 34 (6/2) 32 (6/2) 36 (7/2) (d, pc) (d, pc, xn)* # 16 (4/0) 18 (4/0) 12 (3/0) 16 (4/0) 18 (4/0) 12 (3/0) 24 (4/2) 26 (4/2) 20 (3/2) 24 (4/2) 26 (4/2) 20 (3/2) 24 (4/2) 26 (4/2) 20 (3/2) 28 (5/2) 30 (5/2) 24 (4/2) 30 (5/2) 32 (5/2) 26 (4/2) 28 (5/2) 30 (5/2) 24 (4/2) 32 (5/2) 34 (6/2) 28 (5/2) *the size of the index register (xn) does not affect execution time. 8.3 standard instruction execution times the numbers of clock periods shown in table 8-4 indicate the times required to perform the operations, store the results, and read the next instruction. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+). in table 8-4, the following notation applies: an address register operand dn data register operand ea an operand specified by an effective address m memory effective address operand
8- 4 mc68000 8-/16-/32-microprocessors uiser's manual motorola table 8-4. standard instruction execution times instruction size op, an? op, dn op dn, add/adda byte, word 8 (1/0)+ 4 (1/0)+ 8 (1/1)+ long 6 (1/0)+** 6 (1/0)+** 12 (1/2)+ and byte, word 4 (1/0)+ 8 (1/1)+ long 6 (1/0)+** 12 (1/2)+ cmp/cmpa byte, word 6 (1/0)+ 4 (1/0)+ long 6 (1/0)+ 6 (1/0)+ divs 158 (1/0)+* divu 140 (1/0)+* eor byte, word 4 (1/0)*** 8 (1/1)+ long 8 (1/0)*** 12 (1/2)+ muls 70 (1/0)+* mulu 70 (1/0)+* or byte, word 4 (1/0)+ 8 (1/1)+ long 6 (1/0)+** 12 (1/2)+ sub byte, word 8 (1/0)+ 4 (1/0)+ 8 (1/1)+ long 6 (1/0)+** 6 (1/0)+** 12 (1/2)+ + add effective address calculation time. ? word or long only * indicates maximum basic value added to word effective address time ** the base time of six clock periods is increased to eight if the effective address mode is register direct or immediate (effective address time should also be added). *** only available effective address mode is data register direct. divs, divu the divide algorithm used by the mc68000 provides less than 10% difference between the best- and worst-case timings. muls, mulu the multiply algorithm requires 38+2n clocks where n is defined as: mulu: n = the number of ones in the muls: n=concatenate the with a zero as the lsb; n is the resultant number of 10 or 01 patterns in the 17-bit source; i.e., worst case happens when the source is $5555. 8.4 immediate instruction execution times the numbers of clock periods shown in table 8-5 include the times to fetch immediate operands, perform the operations, store the results, and read the next operation. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+). in table 8-5, the following notation applies: # immediate operand dn data register operand an address register operand m memory operand
motorola mc68000 8-/16-/32-microprocessors user? manual 8- 5 table 8-5. immediate instruction execution times instruction size op #, dn op #, an op #, m addi byte, word 8 (2/0) ?2 (2/1)+ long 16 (3/0) ?0 (3/2)+ addq byte, word 4 (1/0) 4 (1/0)* 8 (1/1)+ long 8 (1/0) 8 (1/0) 12 (1/2)+ andi byte, word 8 (2/0) ?2 (2/1)+ long 14 (3/0) ?0 (3/2)+ cmpi byte, word 8 (2/0) ? (2/0)+ long 14 (3/0) ?2 (3/0)+ eori byte, word 8 (2/0) ?2 (2/1)+ long 16 (3/0) ?0 (3/2)+ moveq long 4 (1/0) ori byte, word 8 (2/0) ?2 (2/1)+ long 16 (3/0) ?0 (3/2)+ subi byte, word 8 (2/0) ?2 (2/1)+ long 16 (3/0) ?0 (3/2)+ subq byte, word 4 (1/0) 8 (1/0)* 8 (1/1)+ long 8 (1/0) 8 (1/0) 12 (1/2)+ 8.5 single operand instruction execution times table 8-6 lists the timing data for the single operand instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+).
8- 6 mc68000 8-/16-/32-microprocessors uiser's manual motorola table 8-6. single operand instruction execution times instruction size register memory clr byte, word 4 (1/0) 8 (1/1)+ long 6 (1/0) 12 (1/2)+ nbcd byte 6 (1/0) 8 (1/1)+ neg byte, word 4 (1/0) 8 (1/1)+ long 6 (1/0) 12 (1/2)+ negx byte, word 4 (1/0) 8 (1/1)+ long 6 (1/0) 12 (1/2)+ not byte, word 4 (1/0) 8 (1/1)+ long 6 (1/0) 12 (1/2)+ scc byte, false 4 (1/0) 8 (1/1)+ byte, true 6 (1/0) 8 (1/1)+ tas byte 4 (1/0) 14 (2/1)+ tst byte, word 4 (1/0) 4 (1/0)+ long 4 (1/0) 4 (1/0)+ +add effective address calculation time. 8.6 shift/rotate instruction execution times table 8-7 lists the timing data for the shift and rotate instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+). table 8-7. shift/rotate instruction execution times instruction size register memory asr, asl byte, word 6+2n (1/0) 8 (1/1)+ long 8+2n (1/0) lsr, lsl byte, word 6+2n (1/0) 8 (1/1)+ long 8+2n (1/0) ror, rol byte, word 6+2n (1/0) 8 (1/1)+ long 8+2n (1/0) roxr, roxl byte, word 6+2n (1/0) 8 (1/1)+ long 8+2n (1/0) +add effective address calculation time for word operands. n is the shift count.
motorola mc68000 8-/16-/32-microprocessors user? manual 8- 7 8.7 bit manipulation instruction execution times table 8-8 lists the timing data for the bit manipulation instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+). table 8-8. bit manipulation instruction execution times dynamic static instruction size register memory register memory bchg byte 8 (1/1)+ 12 (2/1)+ long 8 (1/0)* 12 (2/0)* bclr byte 8 (1/1)+ 12 (2/1)+ long 10 (1/0)* 14 (2/0)* bset byte 8 (1/1)+ 12 (2/1)+ long 8 (1/0)* 12 (2/0)* btst byte 4 (1/0)+ 8 (2/0)+ long 6 (1/0) 10 (2/0) +add effective address calculation time. * indicates maximum value; data addressing mode only. 8.8 conditional instruction execution times table 8-9 lists the timing data for the conditional instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. table 8-9. conditional instruction execution times instruction displacement branch taken branch not taken bcc byte 10 (2/0) 8 (1/0) word 10 (2/0) 12 (2/0) bra byte 10 (2/0) word 10 (2/0) bsr byte 18 (2/2) word 18 (2/2) dbcc cc true 12 (2/0) cc false, count not expired 10 (2/0) cc false, counter expired 14 (3/0)
8- 8 mc68000 8-/16-/32-microprocessors uiser's manual motorola 8.9 jmp, jsr, lea, pea, and movem instruction execution times table 8-10 lists the timing data for the jump (jmp), jump to subroutine (jsr), load effective address (lea), push effective address (pea), and move multiple registers (movem) instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. table 8-10. jmp, jsr, lea, pea, and movem instruction execution times instruction size (an) (an)+ ?an) (d 16 ,an) (d 8 ,an,xn)+ (xxx).w (xxx).l (d 16 pc) (d 8 , pc, xn)* jmp 8 (2/0) 10 (2/0) 14 (3/0) 10 (2/0) 12 (3/0) 10 (2/0) 14 (3/0) jsr 16 (2/2) 18 (2/2) 22 (2/2) 18 (2/2) 20 (3/2) 18 (2/2) 22 (2/2) lea 4(1/0) 8 (2/0) 12 (2/0) 8 (2/0) 12 (3/0) 8 (2/0) 12 (2/0) pea 12 (1/2) 16 (2/2) 20 (2/2) 16 (2/2) 20 (3/2) 16 (2/2) 20 (2/2) movem m r word 12+4n (3+n/0) 12+4n (3+n/0) 16+4n (4+n/0) 18+4n (4+n/0) 16+4n (4+n/0) 20+4n (5+n/0) 16+4n (4n/0) 18+4n (4+n/0) long 12+8n (3+2n/0) 12+8n (3+n/0) 16+8n (4+2n/0) 18+8n (4+2n/0) 16+8n (4+2n/0) 20+8n (5+2n/0) 16+8n (4+2n/0) 18+8n (4+2n/0) movem r m word 8+4n (2/n) 8+4n (2/n) 12+4n (3/n) 14+4n (3/n) 12+4n (3/n) 16+4n (4/n) long 8+8n (2/2n) 8+8n (2/2n) 12+8n (3/2n) 14+8n (3/2n) 12+8n (3/2n) 16+8n (4/2n) n is the number of registers to move. *the size of the index register (xn) does not affect the instruction's execution time. 8.10 multiprecision instruction execution times table 8-11 lists the timing data for multiprecision instructions. the number of clock periods includes the time to fetch both operands, perform the operations, store the results, and read the next instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the following notation applies in table 8-11: dn data register operand m memory operand
motorola mc68000 8-/16-/32-microprocessors user? manual 8- 9 table 8-11. multiprecision instruction execution times instruction size op dn, dn op m, m addx byte, word 4 (1/0) 18 (3/1) long 8 (1/0) 30 (5/2) cmpm byte, word 12 (3/0) long 20 (5/0) subx byte, word 4 (1/0) 18 (3/1) long 8 (1/0) 30 (5/2) abcd byte 6 (1/0) 18 (3/1) sbcd byte 6 (1/0) 18 (3/1) 8.11 miscellaneous instruction execution times tables 8-12 and 8-13 list the timing data for miscellaneous instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+).
8- 10 mc68000 8-/16-/32-microprocessors uiser's manual motorola table 8-12. miscellaneous instruction execution times instruction size register memory andi to ccr byte 20 (3/0) andi to sr word 20 (3/0) chk (no trap) 10 (1/0)+ eori to ccr byte 20 (3/0) eori to sr word 20 (3/0) ori to ccr byte 20 (3/0) ori to sr word 20 (3/0) move from sr 6 (1/0) 8 (1/1)+ move to ccr 12 (1/0) 12 (1/0)+ move to sr 12 (2/0) 12 (2/0)+ exg 6 (1/0) ext word 4 (1/0) long 4 (1/0) link 16 (2/2) move from usp 4 (1/0) move to usp 4 (1/0) nop 4 (1/0) reset 132 (1/0) rte 20 (5/0) rtr 20 (2/0) rts 16 (4/0) stop 4 (0/0) swap 4 (1/0) trapv 4 (1/0) unlk 12 (3/0) +add effective address calculation time. table 8-13. move peripheral instruction execution times instruction size register memory memory register movep word 16 (2/2) 16 (4/0) long 24 (2/4) 24 (6/0) 8.12 exception processing execution times table 8-14 lists the timing data for exception processing. the numbers of clock periods include the times for all stacking, the vector fetch, and the fetch of the first instruction of
motorola mc68000 8-/16-/32-microprocessors user? manual 8- 11 the handler routine. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+). table 8-14. exception processing execution times exception periods address error 50 (4/7) bus error 50 (4/7) chk instruction 40 (4/3)+ divide by zero 38 (4/3)+ illegal instruction 34 (4/3) interrupt 44 (5/3)* privilege violation 34 (4/3) reset ** 40 (6/0) trace 34 (4/3) trap instruction 34 (4/3) trapv instruction 34 (5/3) + add effective address calculation time. * the interrupt acknowledge cycle is assumed to take four clock periods. ** indicates the time from when reset and halt are first sampled as negated to when instruction execution starts.
motorola m68000 8-/16-/32-bit microprocessors user? manual 9- 1 section 9 MC68010 instruction execution times this section contains listings of the instruction execution times in terms of external clock (clk) periods for the MC68010. in this data, it is assumed that both memory read and write cycles consist of four clock periods. a longer memory cycle causes the generation of wait states that must be added to the total instruction times. the number of bus read and write cycles for each instruction is also included with the timing data. this data is shown as n(r/w) where: n is the total number of clock periods r is the number of read cycles w is the number of write cycles for example, a timing number shown as 18(3/1) means that 18 clock cycles are required to execute the instruction. of the 18 clock periods, 12 are used for the three read cycles (four periods per cycle). four additional clock periods are used for the single write cycle, for a total of 16 clock periods. the bus is idle for two clock periods during which the processor completes the internal operations required for the instructions. note the total number of clock periods (n) includes instruction fetch and all applicable operand fetches and stores.
9- 2 m68000 8-/16-/32-bit microprocessors user's manual motorola 9.1 operand effective address calculation times table 9-1 lists the numbers of clock periods required to compute the effective addresses for instructions. the totals include fetching any extension words, computing the address, and fetching the memory operand. the total number of clock periods, the number of read cycles, and the number of write cycles (zero for all effective address calculations) are shown in the previously described format. table 9-1. effective address calculation times byte, word long addressing mode fetch no fetch fetch no fetch dn an register data register direct address register direct 0 (0/0) 0 (0/0) 0 (0/0) 0 (0/0) (an) (an)+ memory address register indirect address register indirect with postincrement 4 (1/0) 4 (1/0) 2 (0/0) 4 (0/0) 8 (2/0) 8 (2/0) 2 (0/0) 4 (0/0) ?an) (d 16 , an) address register indirect with predecrement address register indirect with displacement 6 (1/0) 8 (2/0) 4 (0/0) 4 (0/0) 10 (2/0) 12 (3/0) 4 (0/0) 4 (1/0) (d 8 , an, xn)* (xxx).w address register indirect with index absolute short 10 (2/0) 8 (2/0) 8 (1/0) 4 (1/0) 14 (3/0) 12 (3/0) 8 (1/0) 4 (1/0) (xxx).l (d 16 , pc) absolute long program counter indirect with displacement 12 (3/0) 8 (2/0) 8 (2/0) 16 (4/0) 12 (3/0) 8 (2/0) (d 8 , pc, xn)* # program counter indirect with index immediate 10 (2/0) 4 (1/0) 14 (3/0) 8 (2/0) *the size of the index register (xn) does not affect execution time. 9.2 move instruction execution times tables 9-2, 9-3, 9-4, and 9-5 list the numbers of clock periods for the move instructions. the totals include instruction fetch, operand reads, and operand writes. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format.
motorola m68000 8-/16-/32-bit microprocessors user? manual 9- 3 table 9-2. move byte and word instruction execution times destination source dn an (an) (an)+ ?an) (d 16 , an) (d 8 , an, xn)* (xxx).w (xxx).l dn an (an) 4 (1/0) 4 (1/0) 8 (2/0) 4 (1/0) 4 (1/0) 8 (2/0) 8 (1/1) 8 (1/1) 12 (2/1) 8 (1/1) 8 (1/1) 12 (2/1) 8 (1/1) 8 (1/1) 12 (2/1) 12 (2/1) 12 (2/1) 16 (3/1) 14 (2/1) 14 (2/1) 18 (3/1) 12 (2/1) 12 (2/1) 16 (3/1) 16 (3/1) 16 (3/1) 20 (4/1) (an)+ ?an) (d 16 , an) 8 (2/0) 10 (2/0) 12 (3/0) 8 (2/0) 10 (2/0) 12 (3/0) 12 (2/1) 14 (2/1) 16 (3/1) 12 (2/1) 14 (2/1) 16 (3/1) 12 (2/1) 14 (2/1) 16 (3/1) 16 (3/1) 18 (3/1) 20 (4/1) 18 (3/1) 20 (3/1) 22 (4/1) 16 (3/1) 18 (3/1) 20 (4/1) 20 (4/1) 22 (4/1) 24 (5/1) (d 8 , an, xn)* (xxx).w (xxx).l 14 (3/0) 12 (3/0) 16 (4/0) 14 (3/0) 12 (3/0) 16 (4/0) 18 (3/1) 16 (3/1) 20 (4/1) 18 (3/1) 16 (3/1) 20 (4/1) 18 (3/1) 16 (3/1) 20 (4/1) 22 (4/1) 20 (4/1) 24 (5/1) 24 (4/1) 22 (4/1) 26 (5/1) 22 (4/1) 20 (4/1) 24 (5/1) 26 (5/1) 24 (5/1) 28 (6/1) (d 16 , pc) (d 8 , pc, xn)* # 12 (3/0) 14 (3/0) 8 (2/0) 12 (3/0) 14 (3/0) 8 (2/0) 16 (3/1) 18 (3/1) 12 (2/1) 16 (3/1) 18 (3/1) 12 (2/1) 16 (3/1) 18 (3/1) 12 (2/1) 20 (4/1) 22 (4/1) 16 (3/1) 22 (4/1) 24 (4/1) 18 (3/1) 20 (4/1) 22 (4/1) 16 (3/1) 24 (5/1) 26 (5/1) 20 (4/1) *the size of the index register (xn) does not affect execution time. table 9-3. move byte and word instruction loop mode execution times loop continued loop terminated valid count, cc false valid count, cc true expired count destination source (an) (an)+ ?an) (an) (an)+ ?an) (an) (an)+ ?an) dn an* (an) 10 (0/1) 10 (0/1) 14 (1/1) 10 (0/1) 10 (0/1) 14 (1/1) 16 (1/1) 18 (2/1) 18 (2/1) 20 (3/1) 18 (2/1) 18 (2/1) 20 (3/1) 22 (3/1) 16 (2/1) 16 (2/1) 18 (3/1) 16 (2/1) 16 (2/1) 18 (3/1) 20 (3/1) (an)+ ?an) 14 (1/1) 16 (1/1) 14 (1/1) 16 (1/1) 16 (1/1) 18 (1/1) 20 (3/1) 22 (3/1) 20 (3/1) 22 (3/1) 22 (3/1) 24 (3/1) 18 (3/1) 20 (3/1) 18 (3/1) 20 (3/1) 20 (3/1) 22 (3/1) *word only.
9- 4 m68000 8-/16-/32-bit microprocessors user's manual motorola table 9-4. move long instruction execution times destination source dn an (an) (an)+ ?an) (d 16 , an) (d 8 , an, xn)* (xxx).w (xxx).l dn an (an) 4 (1/0) 4 (1/0) 12 (3/0) 4 (1/0) 4 (1/0) 12 (3/0) 12 (1/2) 12 (1/2) 20 (3/2) 12 (1/2) 12 (1/2) 20 (3/2) 14 (1/2) 14 (1/2) 20 (3/2) 16 (2/2) 16 (2/2) 24 (4/2) 18 (2/2) 18 (2/2) 26 (4/2) 16 (2/2) 16 (2/2) 24 (4/2) 20 (3/2) 20 (3/2) 28 (5/2) (an)+ ?an) (d 16 , an) 12 (3/0) 14 (3/0) 16 (4/0) 12 (3/0) 14 (3/0) 16 (4/0) 20 (3/2) 22 (3/2) 24 (4/2) 20 (3/2) 22 (3/2) 24 (4/2) 20 (3/2) 22 (3/2) 24 (4/2) 24 (4/2) 26 (4/2) 28 (5/2) 26 (4/2) 28 (4/2) 30 (5/2) 24 (4/2) 26 (4/2) 28 (5/2) 28 (5/2) 30 (5/2) 32 (6/2) (d 8 , an, xn)* (xxx).w (xxx).l 18 (4/0) 16 (4/0) 20 (5/0) 18 (4/0) 16 (4/0) 20 (5/0) 26 (4/2) 24 (4/2) 28 (5/2) 26 (4/2) 24 (4/2) 28 (5/2) 26 (4/2) 24 (4/2) 28 (5/2) 30 (5/2) 28 (5/2) 32 (6/2) 32 (5/2) 30 (5/2) 34 (6/2) 30 (5/2) 28 (5/2) 32 (6/2) 34 (6/2) 32 (6/2) 36 (7/2) (d 16 , pc) (d 8 , pc, xn)* # 16 (4/0) 18 (4/0) 12 (3/0) 16 (4/0) 18 (4/0) 12 (3/0) 24 (4/2) 26 (4/2) 20 (3/2) 24 (4/2) 26 (4/2) 20 (3/2) 24 (4/2) 26 (4/2) 20 (3/2) 28 (5/2) 30 (5/2) 24 (4/2) 30 (5/2) 32 (5/2) 26 (4/2) 28 (5/2) 30 (5/2) 24 (4/2) 32 (5/2) 34 (6/2) 28 (5/2) *the size of the index register (xn) does not affect execution time. table 9-5. move long instruction loop mode execution times loop continued loop terminated valid count, cc false valid count, cc true expired count destination source (an) (an)+ ?an) (an) (an)+ ?an) (an) (an)+ ?an) dn an (an) 14 (0/2) 14 (0/2) 22 (2/2) 14 (0/2) 14 (0/2) 22 (2/2) 24 (2/2) 20 (2/2) 20 (2/2) 28 (4/2) 20 (2/2) 20 (2/2) 28 (4/2) 30 (4/2) 18 (2/2) 18 (2/2) 24 (4/2) 18 (2/2) 18 (2/2) 24 (4/2) 26 (4/2) (an)+ ?an) 22 (2/2) 24 (2/2) 22 (2/2) 24 (2/2) 24 (2/2) 26 (2/2) 28 (4/2) 30 (4/2) 28 (4/2) 30 (4/2) 30 (4/2) 32 (4/2) 24 (4/2) 26 (4/2) 24 (4/2) 26 (4/2) 26 (4/2) 28 (4/2) 9.3 standard instruction execution times the numbers of clock periods shown in tables 9-6 and 9-7 indicate the times required to perform the operations, store the results, and read the next instruction. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+). in tables 9-6 and 9-7, the following notation applies: an address register operand sn data register operand ea an operand specified by an effective address m memory effective address operand
motorola m68000 8-/16-/32-bit microprocessors user? manual 9- 5 table 9-6. standard instruction execution times instruction size op, an*** op, dn op dn, add/adda byte, word 8 (1/0)+ 4 (1/0)+ 8 (1/1)+ long 6 (1/0)+ 6 (1/0)+ 12 (1/2)+ and byte, word 4 (1/0)+ 8 (1/1)+ long 6 (1/0)+ 12 (1/2)+ cmp/cmpa byte, word 6 (1/0)+ 4 (1/0)+ long 6 (1/0)+ 6 (1/0)+ divs 122 (1/0)+ divu 108 (1/0)+ eor byte, word 4 (1/0)** 8 (1/1)+ long 6 (1/0)** 12 (1/2)+ muls/mulu 42 (1/0)+* 40 (1/0)* or byte, word 4 (1/0)+ 8 (1/1)+ long 6 (1/0)+ 12 (1/2)+ sub/suba byte, word 8 (1/0)+ 4 (1/0)+ 8 (1/1)+ long 6 (1/0)+ 6 (1/0)+ 12 (1/2)+ + add effective address calculation time. * indicates maximum value. ** only available address mode is data register direct. *** word or long word only. table 9-7 standard instruction loop mode execution times loop continued loop terminated valid count cc false valid count cc true expired count instruction size op, an* op, dn op dn, op, an* op, dn op dn, op, an* op, dn op dn, add byte, word 18 (1/0) 16 (1/0) 16 (1/1) 24 (3/0) 22 (3/0) 22 (3/1) 22 (3/0) 20 (3/0) 20 (3/1) long 22 (2/0) 22 (2/0) 24 (2/2) 28 (4/0) 28 (4/0) 30 (4/2) 26 (4/0) 26 (4/0) 28 (4/2) and byte, word ?6 (1/0) 16 (1/1) ?2 (3/0) 22 (3/1) ?0 (3/0) 20 (3/1) long ?2 (2/0) 24 (2/2) ?8 (4/0) 30 (4/2) ?6 (4/0) 28 (4/2) cmp byte, word 12 (1/0) 12 (1/0) ?8 (3/0) 18 (3/0) ?6 (3/0) 16 (4/0) long 18 (2/0) 18 (2/0) ?4 (4/0) 24 (4/0) ?0 (4/0) 20 (4/0) eor byte, word 16 (1/0) 22 (3/1) 20 (3/1) long 24 (2/2) 30 (4/2) 28 (4/2) or byte, word ?6 (1/0) 16 (1/0) ?2 (3/0) 22 (3/1) ?0 (3/0) 20 (3/1) long ?2 (2/0) 24 (2/2) ?8 (4/0) 30 (4/2) ?6 (4/0) 28 (4/2) sub byte, word 18 (1/0) 16 (1/0) 16 (1/1) 24 (3/0) 22 (3/0) 22 (3/1) 22 (3/0) 20 (3/0) 20 (3/1) long 22 (2/0) 20 (2/0) 24 (2/2) 28 (4/0) 26 (4/0) 30 (4/2) 26 (4/0) 24 (4/0) 28 (4/2) *word or long word only. may be (an), (an)+, or ?an) only. add two clock periods to the table value if is ?an).
9- 6 m68000 8-/16-/32-bit microprocessors user's manual motorola 9.4 immediate instruction execution times the numbers of clock periods shown in table 9-8 include the times to fetch immediate operands, perform the operations, store the results, and read the next operation. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+). in tables 9-8, the following notation applies: # immediate operand dn data register operand an address register operand m memory operand table 9-8. immediate instruction execution times instruction size op #, dn op #, an op #, m addi byte, word 8 (2/0) ?2 (2/1)+ long 14 (3/0) ?0 (3/2)+ addq byte, word 4 (1/0) 4 (1/0)* 8 (1/2)+ long 8 (1/0) 8 (1/1) 12 (1/2)+ andi byte, word 8 (2/0) ?2 (2/1)+ long 14 (3/0) ?0 (3/1)+ cmpi byte, word 8 (2/0) ? (2/0)+ long 12 (3/0) ?2 (3/0)+ eori byte, word 8 (2/0) ?2 (2/1)+ long 14 (3/0) ?0 (3/2)+ moveq long 4 (1/0) ori byte, word 8 (2/0) ?2 (2/1)+ long 14 (3/0) ?0 (3/2)+ subi byte, word 8 (2/0) ?2 (2/1)+ long 14 (3/0) ?0 (3/2)+ subq byte, word 4 (1/0) 4 (1/0)* 8 (1/1)+ long 8 (1/0) 8 (1/0) 12 (1/2)+ +add effective address calculation time. *word only. 9.5 single operand instruction execution times tables 9-9, 9-10, and 9-11 list the timing data for the single operand instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+).
motorola m68000 8-/16-/32-bit microprocessors user? manual 9- 7 table 9-9. single operand instruction execution times instruction size register memory nbcd byte 6 (1/0) 8 (1/1)+ neg byte, word 4 (1/0) 8 (1/1)+ long 6 (1/0) 12 (1/2)+ negx byte, word 4 (1/0) 8 (1/1)+ long 6 (1/0) 12 (1/2)+ not byte, word 4 (1/0) 8 (1/1)+ long 6 (1/0) 12 (1/2)+ scc byte, false 4 (1/0) 8 (1/1)+* byte, true 4 (1/0) 8 (1/1)+* tas byte 4 (1/0) 14 (2/1)+* tst byte, word 4 (1/0) 4 (1/0)+ long 4 (1/0) 4 (1/0)+ +add effective address calculation time. *use nonfetching effective address calculation time. table 9-10. clear instruction execution times size dn an (an) (an)+ ?an) (d 16 , an) (d 8 , an, xn)* (xxx).w (xxx).l clr byte, word 4 (1/0) ? (1/1) 8 (1/1) 10 (1/1) 12 (2/1) 16 (2/1) 12 (2/1) 16 (3/1) long 6 (1/0) ?2 (1/2) 12 (1/2) 14 (1/2) 16 (2/2) 20 (2/2) 16 (2/2) 20 (3/2) *the size of the index register (xn) does not affect execution time.
9- 8 m68000 8-/16-/32-bit microprocessors user's manual motorola table 9-11. single operand instruction loop mode execution times loop continued loop terminated valid count, cc false valid count, cc true expired count instruction size (an) (an)+ ?an) (an) (an)+ ?an) (an) (an)+ (an) clr byte, word 10 (0/1) 10 (0/1) 12 (0/1) 18 (2/1) 18 (2/1) 20 (2/0) 16 (2/1) 16 (2/1) 18 (2/1) long 14 (0/2) 14 (0/2) 16 (0/2) 22 (2/2) 22 (2/2) 24 (2/2) 20 (2/2) 20 (2/2) 22 (2/2) nbcd byte 18 (1/1) 18 (1/1) 20 (1/1) 24 (3/1) 24 (3/1) 26 (3/1) 22 (3/1) 22 (3/1) 24 (3/1) neg byte, word 16 (1/1) 16 (1/1) 18 (2/2) 22 (3/1) 22 (3/1) 24 (3/1) 20 (3/1) 20 (3/1) 22 (3/1) long 24 (2/2) 24 (2/2) 26 (2/2) 30 (4/2) 30 (4/2) 32 (4/2) 28 (4/2) 28 (4/2) 30 (4/2) negx byte, word 16 (1/1) 16 (1/1) 18 (2/2) 22 (3/1) 22 (3/1) 24 (3/1) 20 (3/1) 20 (3/1) 22 (3/1) long 24 (2/2) 24 (2/2) 26 (2/2) 30 (4/2) 30 (4/2) 32 (4/2) 28 (4/2) 28 (4/2) 30 (4/2) not byte, word 16 (1/1) 16 (1/1) 18 (2/2) 22 (3/1) 22 (3/1) 24 (3/1) 20 (3/1) 20 (3/1) 22 (3/1) long 24 (2/2) 24 (2/2) 26 (2/2) 30 (4/2) 30 (4/2) 32 (4/2) 28 (4/2) 28 (4/2) 30 (4/2) tst byte, word 12 (1/0) 12 (1/0) 14 (1/0) 18 (3/0) 18 (3/0) 20 (3/0) 16 (3/0) 16 (3/0) 18 (3/0) long 18 (2/0) 18 (2/0) 20 (2/0) 24 (4/0) 24 (4/0) 26 (4/0) 20 (4/0) 20 (4/0) 22 (4/0) 9.6 shift/rotate instruction execution times tables 9-12 and 9-13 list the timing data for the shift and rotate instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+). table 9-12. shift/rotate instruction execution times instruction size register memory* asr, asl byte, word 6+2n (1/0) 8 (1/1)+ long 8+2n (1/0) lsr, lsl byte, word 6+2n (1/0) 8 (1/1)+ long 8+2n (1/0) ror, rol byte, word 6+2n (1/0) 8 (1/1)+ long 8+2n (1/0) roxr, roxl byte, word 6+2n (1/0) 8 (1/1)+ long 8+2n (1/0) +add effective address calculation time. n is the shift or rotate count. * word only.
motorola m68000 8-/16-/32-bit microprocessors user? manual 9- 9 table 9-13. shift/rotate instruction loop mode execution times loop continued loop terminated valid count cc false valid count cc true expired count instruction size (an) (an)+ ?an) (an) (an)+ ?an) (an) (an)+ (an) asr, asl word 18 (1/1) 18 (1/1) 20 (1/1) 24 (3/1) 24 (3/1) 26 (3/1) 22 (3/1) 22 (3/1) 24 (3/1) lsr, lsl word 18 (1/1) 18 (1/1) 20 (1/1) 24 (3/1) 24 (3/1) 26 (3/1) 22 (3/1) 22 (3/1) 24 (3/1) ror, rol word 18 (1/1) 18 (1/1) 20 (1/1) 24 (3/1) 24 (3/1) 26 (3/1) 22 (3/1) 22 (3/1) 24 (3/1) roxr, roxl word 18 (1/1) 18 (1/1) 20 (1/1) 24 (3/1) 24 (3/1) 26 (3/1) 22 (3/1) 22 (3/1) 24 (3/1) 9.7 bit manipulation instruction execution times table 9-14 lists the timing data for the bit manipulation instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+). table 9-14. bit manipulation instruction execution times dynamic static instruction size register memory register memory bchg byte 8 (1/1)+ 12 (2/1)+ long 8 (1/0)* 12 (2/0)* bclr byte 10 (1/1)+ 14 (2/1)+ long 10 (1/0)* 14 (2/0)* bset byte 8 (1/1)+ 12 (2/1)+ long 8 (1/0)* 12 (2/0)* btst byte 4 (1/0)+ 8 (2/0)+ long 6 (1/0)* 10 (2/0) +add effective address calculation time. * indicates maximum value; data addressing mode only. 9.8 conditional instruction execution times table 9-15 lists the timing data for the conditional instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format.
9- 10 m68000 8-/16-/32-bit microprocessors user's manual motorola table 9-15. conditional instruction execution times instruction displacement branch taken branch not taken bcc byte 10 (2/0) 6 (1/0) word 10 (2/0) 10 (2/0) bra byte 10 (2/0) word 10 (2/0) bsr byte 18 (2/2) word 18 (2/2) dbcc cc true 10 (2/0) cc false 10 (2/0) 16 (3/0) 9.9 jmp, jsr, lea, pea, and movem instruction execution times table 9-16 lists the timing data for the jump (jmp), jump to subroutine (jsr), load effective address (lea), push effective address (pea), and move multiple registers (movem) instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. table 9-16. jmp, jsr, lea, pea, and movem instruction execution times instruction size (an) (an)+ ?an) (d 16 ,an) (d 8 ,an,xn)+ (xxx) w (xxx).l (d 8 pc) (d 16 , pc, xn)* jmp 8 (2/0) 10 (2/0) 14 (3/0) 10 (2/0) 12 (3/0) 10 (2/0) 14 (3/0) jsr 16 (2/2) 18 (2/2) 22 (2/2) 18 (2/2) 20 (3/2) 18 (2/2) 22 (2/2) lea 4(1/0) 8 (2/0) 12 (2/0) 8 (2/0) 12 (3/0) 8 (2/0) 12 (2/0) pea 12 (1/2) 16 (2/2) 20 (2/2) 16 (2/2) 20 (3/2) 16 (2/2) 20 (2/2) movem m r word 12+4n (3+n/0) 12+4n (3+n/0) 16+4n (4+n/0) 18+4n (4+n/0) 16+4n (4+n/0) 20+4n (5+n/0) 16+4n (4+n/0) 18+4n (4+n/0) long 24+8n (3+2n/0) 12+8n (3+2n/0) 16+8n (4+2n/0) 18+8n (4+2n/0) 16+8n (4+2n/0) 20+8n (5+2n/0) 16+8n (4+2n/0) 18+8n (4+2n/0) movem r m word 8+4n (2/n) 8+4n (2/n) 12+4n (3/n) 14+4n (3/n) 12+4n (3/n) 16+4n (4/n) long 8+8n (2/2n) 8+8n (2/2n) 12+8n (3/2n) 14+8n (3/2n) 12+8n (3/2n) 16+8n (4/2n) moves m r byte/ word 18 (3/0) 20 (3/0) 20 (3/0) 20 (4/0) 24 (4/0) 20 (4/0) 24 (5/0) long 22 (4/0) 24 (4/0) 24 (4/0) 24 (5/0) 28 (5/0) 24 (5/0) 28 (6/0) moves r m byte/ word 18 (2/1) 20 (2/1) 20 (2/1) 20 (3/1) 24 (3/1) 20 (3/1) 24 (4/1) long 22 (2/2) 24 (2/2) 24 (2/2) 24 (3/2) 28 (3/2) 24 (3/2) 28 (4/2) n is the number of registers to move. *the size of the index register (xn) does not affect the instruction's execution time. 9.10 multiprecision instruction execution times table 9-17 lists the timing data for multiprecision instructions. the numbers of clock periods include the times to fetch both operands, perform the operations, store the results,
motorola m68000 8-/16-/32-bit microprocessors user? manual 9- 11 and read the next instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the following notation applies in table 9-17: dn data register operand m memory operand table 9-17. multiprecision instruction execution times loop mode nonlooped continued terminated valid count, cc false valid count, cc true expired count instruction size op dn, dn op m, m* addx byte, word 4 (1/0) 18 (3/1) 22 (2/1) 28 (4/1) 26 (4/1) long 6 (1/0) 30 (5/2) 32 (4/2) 38 (6/2) 36 (6/2) cmpm byte, word 12 (3/0) 14 (2/0) 20 (4/0) 18 (4/0) long 20 (5/0) 24 (4/0) 30 (6/0) 26 (6/0) subx byte, word 4 (1/) 18 (3/1) 22 (2/1) 28 (4/1) 26 (4/1) long 6 (1/0) 30 (5/2) 32 (4/2) 38 (6/2) 36 (6/2) abcd byte 6 (1/0) 18 (3/1) 24 (2/1) 30 (4/1) 28 (4/1) sbcd byte 6 (1/0) 18 (3/1) 24 (2/1) 30 (4/1) 28 (4/1) *source and destination ea are (an)+ for cmpm and ?an) for all others. 9.11 miscellaneous instruction execution times table 9-18 lists the timing data for miscellaneous instructions. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+).
9- 12 m68000 8-/16-/32-bit microprocessors user's manual motorola table 9-18. miscellaneous instruction execution times instruction size register memory register destination** source** register andi to ccr 16 (2/0) andi to sr 16 (2/0) chk 8 (1/0)+ eori to ccr 16 (2/0) eori to sr 16 (2/0) exg 6 (1/0) ext word 4 (1/0) long 4 (1/0) link 16 (2/2) move from ccr 4 (1/0) 8 (1/1)+* move to ccr 12 (2/0) 12 (2/0)+ move from sr 4 (1/0) 8 (1/1)+* move to sr 12 (2/0) 12 (2/0)+ move from usp 6 (1/0) move to usp 6 (1/0) movec ?0 (2/0) 12 (2/0) movep word 16 (2/2) 16 (4/0) long 24 (2/4) 24 (6/0) nop 4 (1/0) ori to ccr 16 (2/0) ori to sr 16 (2/0) reset 130 (1/0) rtd 16 (4/0) rte short 24 (6/0) long, retry read 112 (27/10) long, retry write 112 (26/1) long, no retry 110 (26/0) rtr 20 (5/0) rts 16 (4/0) stop 4 (0/0) swap 4 (1/0) trapv 4 (1/0) unlk 12 (3/0) +add effective address calculation time. +use nonfetching effective address calculation time. **source or destination is a memory location for the movep instruction and a control register for the movec instruction.
motorola m68000 8-/16-/32-bit microprocessors user? manual 9- 13 9.12 exception processing execution times table 9-19 lists the timing data for exception processing. the numbers of clock periods include the times for all stacking, the vector fetch, and the fetch of the first instruction of the handler routine. the total number of clock periods, the number of read cycles, and the number of write cycles are shown in the previously described format. the number of clock periods, the number of read cycles, and the number of write cycles, respectively, must be added to those of the effective address calculation where indicated by a plus sign (+). table 9-19. exception processing execution times exception address error 126 (4/26) breakpoint instruction* 45 (5/4) bus error 126 (4/26) chk instruction** 44 (5/4)+ divide by zero 42 (5/4)+ illegal instruction 38 (5/4) interrupt* 46 (5/4) movec, illegal control register** 46 (5/4) privilege violation 38 (5/4) reset*** 40 (6/0) rte, illegal format 50 (7/4) rte, illegal revision 70 (12/4) trace 38 (4/4) trap instruction 38 (4/4) trapv instruction 38 (5/4) + add effective address calculation time. * the interrupt acknowledge and breakpoint cycles are assumed to take four clock periods. ** indicates maximum value. *** indicates the time from when reset and halt are first sampled as negated to when instruction execution starts.
motorola m68000 8-/16-/32-bit microprocessors user's manual 10-1 this device contains protective circuitry against damage due to high static voltages or electrical fields; however, it is advised that normal precautions be taken to avoid application of any voltages higher than maximum-rated voltages to this high-impedance circuit. reliability of operation is enhanced if unused inputs are tied to an appropriate logic voltage level (e.g., either gnd or v cc ). section 10 electrical and thermal characteristics this section provides information on the maximum rating and thermal characteristics for the mc68000, mc68hc000, mc68hc001, mc68ec000, mc68008, and MC68010. 10.1 maximum ratings rating symbol value unit supply voltage v cc ?.3 to 7.0 v input voltage v in ?.3 to 7.0 v maximum operating temperature range commerical extended "c" grade commerical extended "i" grade t a t l to t h 0 to 70 ?0 to 85 0 to 85 c storage temperature t stg ?5 to 150 c 10.2 thermal characteristics characteristic symbol value symbol value rating thermal resistance ceramic, type l/lc ceramic, type r/rc plastic, type p plastic, type fn q ja 30 33 30 45* q jc 15* 15 15* 25* c/w *estimated
10-2 m68000 8-/16-/32-bit microprocessors user's manual motorola 10.3 power considerations the average die-junction temperature, t j , in c can be obtained from: t j = t a +(p d ? q j a ) (1) where: t a = ambient temperature, c q j a = package thermal resistance, junction-to-ambient, c/w p d = p int + p i/o p int = i cc x v cc , watts ?chip internal power p i/o = power dissipation on input and output pins ?user determined for most applications, p i/o

motorola m68000 8-/16-/32-bit microprocessors user's manual 10-3 table 10-1 summarizes maximum power dissipation and average junction temperature for the curve drawn in figure 10-1, using the minimum and maximum values of ambient temperature for different packages and substituting q j c for q j a (assuming good thermal management). table 10-2 provides the maximum power dissipation and average junction temperature assuming that no thermal management is applied (i.e., still air). note since the power dissipation curve shown in figure 10-1 is negatively sloped, power dissipation declines as ambient temperature increases. therefore, maximum power dissipation occurs at the lowest rated ambient temperature, but the highest average junction temperature occurs at the maximum ambient temperature where power dissipation is lowest . power (p ), watts d ambient temperature (t ), c a 2.2 2.0 1.8 1.6 1.4 1.2 1.0 -55 -40 0 25 70 85 110 125 8, 10, 12.5 mhz 16.67 mhz figure 10-1. mc68000 power dissipation (p d ) vs ambient temperature (t a ) (not applicable to mc68hc000/68hc001/68ec000)
10-4 m68000 8-/16-/32-bit microprocessors user's manual motorola table 10-1. power dissipation and junction temperature vs temperature ( q j c = q j a ) package t a range q j c ( c/w) p d (w) @ t a min. t j ( c) @ t a min. p d (w) @ t a max. t j ( c) @ t a max. l/lc 0 c to 70 c -40 c to 85 c 0 c to 85 c 15 15 15 1.5 1.7 1.5 23 -14 23 1.2 1.2 1.2 88 103 103 p0 c to 70 c 15 1.5 23 1.2 88 r/rc 0 c to 70 c -40 c to 85 c 0 c to 85 c 15 15 15 1.5 1.7 1.5 23 -14 23 1.2 1.2 1.2 88 103 103 fn 0 c to 70 c 25 1.5 38 1.2 101 note: table does not include values for the mc68000 12f. does not apply to the mc68hc000, mc68hc001, and mc68ec000. table 10-2. power dissipation and junction temperature vs temperature ( q j c 1 q j c ) package t a range q j a ( c/w) p d (w) @ t a min. t j ( c) @ t a min. p d (w) @ t a max. t j ( c) @ t a max. l/lc 0 c to 70 c -40 c to 85 c 0 c to 85 c 30 30 30 1.5 1.7 1.5 23 -14 23 1.2 1.2 1.2 88 103 103 p0 c to 70 c 30 1.5 23 1.2 88 r/rc 0 c to 70 c -40 c to 85 c 0 c to 85 c 33 33 33 1.5 1.7 1.5 23 -14 23 1.2 1.2 1.2 88 103 103 fn 0 c to 70 c 40 1.5 38 1.2 101 note: table does not include values for the mc68000 12f. does not apply to the mc68hc000, mc68hc001, and mc68ec000. values for thermal resistance presented in this manual, unless estimated, were derived using the procedure described in motorola reliability report 7843 ?hermal resistance measurement method for mc68xxx microcomponent devices and are provided for design purposes only. thermal measurements are complex and dependent on procedure and setup. user-derived values for thermal resistance may differ. 10.4 cmos considerations the mc68hc000, mc68hc001, and mc68ec000, with it significantly lower power consumption, has other considerations. the cmos cell is basically composed of two complementary transistors (a p channel and an n channel), and only one transistor is turned on while the cell is in the steady state. the active p-channel transistor sources current when the output is a logic high and presents a high impedance when the output is logic low. thus, the overall result is extremely low power consumption because no power
motorola m68000 8-/16-/32-bit microprocessors user's manual 10-5 is lost through the active p-channel transistor. also, since only one transistor is turned on during the steady state, power consumption is determined by leakage currents. because the basic cmos cell is composed of two complementary transistors, a virtual semiconductor controlled rectifier (scr) may be formed when an input exceeds the supply voltage. the scr that is formed by this high input causes the device to become latched in a mode that may result in excessive current drain and eventual destruction of the device. although the mc68hc000 and mc68ec000 is implemented with input protection diodes, care should be exercised to ensure that the maximum input voltage specification is not exceeded. some systems may require that the cmos circuitry be isolated from voltage transients; other may require additional circuitry. the mc68hc000 and mc68ec000, implemented in cmos, is applicable to designs to which the following considerations are relevant: 1. the mc68hc000 and mc68ec000 completely satisfies the input/output drive requirements of cmos logic devices. 2. the hcmos mc68hc000 and mc68ec000 provides an order of magnitude reduction in power dissipation when compared to the hmos mc68000. however, the mc68hc000 does not offer a "power-down" mode. 10.5 ac electrical specification definitions the ac specifications presented consist of output delays, input setup and hold times, and signal skew times. all signals are specified relative to an appropriate edge of the clock and possibly to one or more other signals. the measurement of the ac specifications is defined by the waveforms shown in figure 10-2. to test the parameters guaranteed by motorola, inputs must be driven to the voltage levels specified in the figure. outputs are specified with minimum and/or maximum limits, as appropriate, and are measured as shown. inputs are specified with minimum setup and hold times, and are measured as shown. finally, the measurement for signal-to-signal specifications are shown. note the testing levels used to verify conformance to the ac specifications does not affect the guaranteed dc operation of the device as specified in the dc electrical characteristics.
10-6 m68000 8-/16-/32-bit microprocessors user's manual motorola b a drive to 0.5 v 2.0 v 0.8 v valid output n valid output n + 1 2.0 v 0.8 v valid input 2.0 v 0.8 v 2.0 v 0.8 v d c drive to 0.5 v drive to 2.4 v 2.0 v 2.0 v 0.8 v e f bclk outputs(1) inputs(2) rsti (3) notes: 1. this output timing is applicable to all parameters specified relative to the rising edge of the clock. 2. this input timing is applicable to all parameters specified relative to the rising edge of the clock. 3. this timing is applicable to all parameters specified relative to the negation of the reset signal. legend: a. maximum output delay specification. b. minimum output hold time. c. minimum input setup time specification. d. minimum input hold time specification. e. mode select setup time to reset negated. f. mode select hold time from reset negated. drive to 2.4 v 1.5 v 1.5 v figure 10-2. drive levels and test points for ac specifications
motorola m68000 8-/16-/32-bit microprocessors user's manual 10-7 10.6 mc68000/68008/68010 dc electrical characteristics (v cc =5.0 vdc 5%; gnd=0 vdc; t a =t l to t h ) characteristic symbol min max unit input high voltage v ih 2.0 v cc v input low voltage v il gnd-0.3 0.8 v input leakage current berr , bgack , br , dtack , clk, ipl0?ipl2 , vpa @ 5.25 v halt, reset i in 2.5 20 m a three-state (off state) input current as , a1?23, d0?15, fc0?c2, @ 2.4 v/0.4 v lds , r/ w , uds , vma i tsi ?0 m a output high voltage (i oh = ?00 m a) e* (i oh = -400 m a) as , a1?23, bg , d0?15, fc0?c2, lds , r/ w , uds, vma v oh v cc ?.75 2.4 2.4 v output low voltage (i ol = 1.6 ma) halt (i ol = 3.2 ma) a1?23, bg , fc0-fc2 (i ol = 5.0 ma) reset (i ol = 5.3 ma) e, as , d0?15, lds , r/ w, uds, vma v ol 0.5 0.5 0.5 0.5 v power dissipation (see power considerations) p d ***w capacitance (v in =0 v, t a =25 c, frequency=1 mhz)** c in 20.0 pf load capacitance halt all others c l 70 130 pf *with external pullup resistor of 1.1 w . **capacitance is periodically sampled rather than 100% tested. ***during normal operation, instantaneous v cc current requirements may be as high as 1.5 a.
10-8 m68000 8-/16-/32-bit microprocessors user's manual motorola 10.7 dc electrical characteristics (v cc =5.0 vdc 5%; gnd=0 vdc; t a =t l to t h ) (applies to all processors except the mc68ec000) characteristic symbol min max unit input high voltage v ih 2.0 v cc v input low voltage v il gnd-0.3 0.8 v input leakage current berr , bgack , br , dtack , clk, ipl0?ipl2 , vpa @ 5.25 v mode, halt, reset i in 2.5 20 m a three-state (off state) input current as , a0?23, d0?15, @ 2.4 v/0.4 v fc0?c2, lds , r/ w , uds, vma i tsi ?0 m a output high voltage e, as , a0?23, bg , d0?15, fc0?c2, lds , r/ w , uds, vma v oh v cc ?.75 v output low voltage (i ol = 1.6 ma) halt (i ol = 3.2 ma) a0?23, bg , fc0-fc2 (i ol = 5.0 ma) reset (i ol = 5.3 ma) e, as , d0?15, lds , r/ w, uds, vma v ol 0.5 0.5 0.5 0.5 v current dissipation* f = 8 mhz f = 10 mhz f = 12.5 mhz f = 16.67 mhz f = 20 mhz i d 25 30 35 50 70 ma power dissipation f = 8 mhz f = 10 mhz f = 12.5 mhz f = 16.67 mhz f = 20 mhz p d 0.13 0.16 0.19 0.26 0.38 w capacitance (v in = 0 v, t a =25 c, frequency=1 mhz)** c in 20.0 pf load capacitance halt all others c l 70 130 pf * current listed are with no loading. ** capacitance is periodically sampled rather than 100% tested. 10.8 ac electrical specifications ?clock timing ( see figure 10-3) (applies to all processors except the mc68ec000) num characteristic 8 mhz* 10 mhz* 12.5 mhz* 16.67 mhz 12f 16 mhz 20 mhz ** unit min max min max min max min max min max min max frequency of operation 4.0 8.0 4.0 10.0 4.0 12.5 8.0 16.7 8.0 16.7 8.0 20.0 mhz 1 cycle time 125 250 100 250 80 250 60 125 60 125 50 125 ns 2,3 clock pulse width (measured from 1.5 v to 1.5 v for 12f) 55 55 125 125 45 45 125 125 35 35 125 125 27 27 62.5 62.5 27 27 62.5 62.5 21 21 62.5 62.5 ns 4,5 clock rise and fall times 10 10 10 10 5 5 5 5 5 5 4 4 ns *these specifications represent an improvement over previously published specifications for the 8-, 10-, and 12.5- mhz mc68000 and are valid only for product bearing date codes of 8827 and later. **this frequency applies only to mc68hc000 and mc68ec000 parts.
motorola m68000 8-/16-/32-bit microprocessors user's manual 10-9 10.9 mc68008 ac electrical specifications ?clock timing (see figure 10-3) num characteristic 8 mhz* 10 mhz* unit min max min max frequency of operation 2.0 8.0 2.0 10.0 mhz 1 cycle time 125 500 100 500 ns 2,3 clock pulse width 55 250 45 250 ns 4,5 clock rise and fall times 10 10 ns *these specifications represent an improvement over previously published specifications for the 8-, and 10-mhz mc68008 and are valid only for product bearing date codes of 8827 and later . 0.8 v 2.0 v timing measurements are referenced to and from a low voltage of 0.8 v and a high voltage of 2.0 v, unless otherwise noted. the voltage swing through this range should start outside and pass through the range such that the rise or fall will be linear between 0.8 v and 2.0 v. note: 4 5 2 1 3 figure 10-3. clock input timing diagram
10-10 m68000 8-/16-/32-bit microprocessors user's manual motorola 10.10 ac electrical specifications ?read and write cycles (v cc =5.0 vdc 5 + ; gnd=0 v; t a =t l to t h ; (see figures 10-4 and 10-5) (applies to all processors except the mc68ec000) num characteristic 8 mhz* 10 mhz* 12.5 mhz* 16.67 mhz 12f 16 mhz 20 mhz unit min max min max min max min max min max min max 6 clock low to address valid 62 50 50 50 30 25 ns 6a clock high to fc valid 62 50 45 45 0 30 0 25 ns 7 clock high to address, data bus high impedance (maximum) 80 70 60 50 50 42 ns 8 clock high to address, fc invalid (minimum) 0 0 0 0 0 0?s 9 1 clock high to as, ds asserted 360350340340330325ns 11 2 address valid to as, ds asserted (read)/ as asserted (write) 30 20 15 15 15 10 ns 11a 2 fc valid to as ), ds asserted (read)/ as ) asserted (write) 90 70 60 30 45 40 ns 12 1 clock low to as, ds negated 62 50 40 40 3 30 3 25 ns 13 2 as, ds negated to address, fc invalid 40 30 20 10 15 10 ns 14 2 asand ds read) width asserted 270 195 160 120 120 100 ns 14a ds width asserted (write) 140 95 80 60 60 50 ns 15 2 as, ds width negated 150 105 65 60 60 50 ns 16 clock high to control bus high impedance ?0?0?0?0?0?2 ns 17 2 as, ds negated to r/ w invalid 40 30 20 10 15 10 ns 18 1 clock high to r/ w high (read) 055045040040030025ns 20 1 clock high to r/ w low (write) 055045040040030025ns 20a 2,6 as asserted to r/ w valid (write) ?0?0?0?0?0?0 ns 21 2 address valid to r/ w low (write) 20?????ns 21a 2 fc valid to r/ w low (write) 60 50 30 20 30 25 ns 22 2 r/ w low to ds asserted (write) 80 50 30 20 30 25 ns 23 clock low to data-out valid (write) 62 50 50 550 30 25 ns 25 2 as, ds ) negated to data-out invalid (write) 40 1 0 ?0?0?5?5?0 ns
motorola m68000 8-/16-/32-bit microprocessors user's manual 10-11 num characteristic 8 mhz* 10 mhz* 12.5 mhz* 16.67 mhz 12f 16 mhz 20 mhz unit min max min max min max min max min max min max 26 2 data-out valid to ds asserted (write) 40 30 20 15 15 10 ns 27 5 data-in valid to clock low (setup time on read) 101010???ns 27a 5 late berr asserted to clock low (setup time) 454545 ns 28 2 as, ds negated to dtack negated (asynchronous hold) 0 240 1 1 0 190 0 150 0 110 0 110 0 95 ns 28a as, ds negated to data-in high impedance 187 150 120 110 110 95 ns 29 as, ds negated to data-in invalid (hold time on read) 0 0 0 0 0 0?s 29a as, ds negated to data-in high impedance 187 150 120 90 90 75 ns 30 as, ds ) negated to berr negated 0 0 0 0 0 0?s 31 2,5 dtack asserted to data-in valid (setup time) ?0?5?0?0?0?2 ns 32 halt ) and reset input transition time 0 200 0 200 0 200 0 150 150 0 150 ns 33 clock high to bg asserted 62 50 40 40 0 30 0 25 ns 34 clock high to bg negated 62 50 40 40 0 30 0 25 ns 35 br asserted to bg asserted 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 clks 36 7 br negated to bg negated 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 clks 37 bgack asserted to bg negated 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 clks 37a 8 bgack asserted to br negated 20 1.5 clks 20 1.5 clks 20 1.5 clks 10 1.5 clks 10 1.5 clks 10 1.5 clks ns 38 bg asserted to control, address, data bus high impedance ( as negated) ?0?0?0?0?0?2 ns 39 bg width negated 1.5 1.5 1.5 1.5 1.5 1.5 clks 40 clock low to vma asserted 70 70 70 50 50 40 ns 41 clock low to e transition 55 12 ?5?5?5?5?0 ns 42 e output rise and fall time 15 15 15 15 15 12 ns 43 vma asserted to e high 200 150 90 80 80 60 ns 44 as, ds negated to vpa negated 0 120 0 90 0 70 0 50 0 50 0 42 ns 45 e low to control, address bus invalid (address hold time) 30 10 10 10 10 10 ns 46 bgack width low 1.5 1.5 1.5 1.5 1.5 1.5 ns
10-12 m68000 8-/16-/32-bit microprocessors user's manual motorola num characteristic 8 mhz* 10 mhz* 12.5 mhz* 16.67 mhz 12f 16 mhz 20 mhz unit min max min max min max min max min max min max 47 5 asynchronous input setup time 10101010 5 5?s 48 2 , 3 berr asserted to dtack asserted 20 20 20 10 10 10 ns 48 2,3,5 dtack asserted to berr asserted (MC68010 only) ?0?5?5 ns 49 9 as, ds, negated to e low -70 70 -55 55 -45 45 -35 35 -35 35 ?0 30 ns 50 e width high 450 350 280 220 220 190 ns 51 e width low 700 550 440 340 340 290 ns 53 data-out hold from clock high 0 0 0 0 0 0?s 54 e low to data-out invalid 30 20 15 10 10 5 ns 55 r/ w asserted to data bus impedance change 302010???ns 56 4 halt ( reset pulse width 10 10 10 10 10 10 clks 57 bgack negated to as, ds , r/ w driven 1.5 1.5 1.5 1.5 1.5 1.5 clks 57a bgack negated to fc, vma driven 1 1 1 1 1 1 clks 58 7 br negated to as , ds , r/ w driven 1.5 1.5 1.5 1.5 1.5 1.5 clks 58a 7 br negated to fc, as driven 1 1 1 1 1 1 clks *these specifications represent improvement over previously published specifications for the 8-, 10-, and 12.5-mhz mc68000 and are valid only for product bearing date codes of 8827 and later. ** this frequency applies only to mc68hc000 and mc68hc001. notes: 1. for a loading capacitance of less than or equal to 50 pf, subtract 5 ns from the value given in the maximum columns. 2. actual value depends on clock period. 3. if #47 is satisfied for both dtack and berr , #48 may be ignored. in the absence of dtack , berr is an asynchronous input using the asynchronous input setup time (#47). 4. for power-up, the mc68000 must be held in the reset state for 100 ms to allow stabilization of on-chip circuitry. after the system is powered up, #56 refers to the minimum pulse width required to reset the processor. 5. if the asynchronous input setup time (#47) requirement is satisfied for dtack , the dtack asserted to data setup time (#31) requirement can be ignored. the data must only satisfy the data-in to clock low setup time (#27) for the following clock cycle. 6. when as and r/ w are equally loaded ( 20;pc), subtract 5 ns from the values given in these columns. 7. the processor will negate bg and begin driving the bus again if external arbitration logic negates br before asserting bgack . 8. the minimum value must be met to guarantee proper operation. if the maximum value is exceeded, bg may be reasserted. 9. the falling edge of s6 triggers both the negation of the strobes ( as and ds ) and the falling edge of e. either of these events can occur first, depending upon the loading on each signal. specification #49 indicates the absolute maximum skew that will occur between the rising edge of the strobes and the falling edge of e. 10. 245 ns for the mc68008. 11. 50 ns for the mc68008 12. 50 ns for the mc68008.
motorola m68000 8-/16-/32-bit microprocessors user's manual 10-13 6a 8 6 13 14 12 17 18 47 28 29 27 48 47 30 47 32 56 47 32 s0 s1 s2 s3 s4 s5 s6 clk fc2?c0 a23?0 as lds / uds r/w dtack data in berr / br (note 2) halt / reset 47 asynchronous inputs (note 1) s7 31 7 11 11a notes: 1. setup time for the asynchronous inputs ipl2?pl0 and avec (#47) guarantees their recognition at the next falling edge of the clock. 2. br need fall at this time only to insure being recognized at the end of the bus cycle. 3. timing measurements are referenced to and from a low voltage of 0.8 v and a high voltage of 2.0 v, unless otherwise noted. the voltage swing through this range should start outside and pass through the range such that the rise or fall is linear between 0.8 v and 2.0 v. 9 15 29a figure 10-4. read cycle timing diagram (a pplies to a ll p rocessors e xcept the m c68ec 000)
10-14 m68000 8-/16-/32-bit microprocessors user's manual motorola 6a 8 6 15 13 9 14 12 17 18 47 28 25 26 48 47 30 47 32 56 47 32 s0 s1 s2 s3 s4 s5 s6 clk fc2-fc0 a23-a1 as lds / uds r/w dtack data out berr / br (note 2) halt / reset 47 asynchronous inputs (note 1) s7 notes: 1. timing measurements are referenced to and from a low voltage of 0.8 v and a high voltage of 2.0 v, unless otherwise noted. the voltage swing through this range should start outside and pass through the range such that the rise or fall is linear between 0.8 v and 2.0 v. 2. because of loading variations, r/w may be valid after as even though both are initiated by the rising edge of s2 (specification #20a). 23 21a 7 11 11a 9 14a 53 7 55 21 22 20a 20 figure 10-5. write cycle timing diagram (a pplies to a ll p rocessors e xcept the m c68ec 000)
motorola m68000 8-/16-/32-bit microprocessors user's manual 10-15 10.11 ac electrical specifications?c68000 to m6800 peripheral (v cc = 5.0 v dc 5%; gnd=0 vdc; t a = t l to t h ; refer to figures 10-6) (applies to all processors except the mc68ec000) num characteristic 8 mhz* 10 mhz* 12.5 mhz* 16.67 mhz `12f' 16 mhz 20 mhz unit min max min max min max min max min max min max 12 1 clock low to as, ds negated 62 50 40 40 3 30 3 25 ns 18 1 clock high to r/ w high (read) 055045040040030025ns 20 1 clock high to r/ w low (write) 055045040040030025ns 23 clock low to data-out valid (write) ?2?0?0?0?0?5 ns 27 data-in valid to clock low (setup time on read) 101010???ns 29 as, ds negated to data-in invalid (hold time on read) 0 0 0 0 0 0?s 40 clock low to vma asserted 70 70 70 50 50 40 ns 41 clock low to e transition 55 45 35 35 35 30 ns 42 e output rise and fall time 15 15 15 15 15 12 ns 43 vma asserted to e high 200 150 90 80 80 60 ns 44 as, ds negated to vpa negated 0 120 0 90 0 70 0 50 0 50 0 42 ns 45 e low to control, address bus invalid (address hold time) 30 10 10 10 10 10 ns 47 asynchronous input setup time 10 10 10 10 10 5 ns 49 2 as, ds , negated to e low -70 70 -55 55 -45 45 -35 35 -35 35 ?0 30 ns 50 e width high 450 350 280 220 220 190 ns 51 e width low 700 550 440 340 340 290 ns 54 e low to data-out invalid 30 20 15 10 10 5 ns *these specifications represent improvement over previously published specifications for the 8-, 10-, and 12.5-mhz mc68000 and are valid only for product bearing date codes of 8827 and later. ** this frequency applies only to mc68hc000 and mc68hc001. notes: 1. for a loading capacitance of less than or equal to 50 pf, subtract 5 ns from the value given in the maximum columns. 2. the falling edge of s6 triggers both the negation of the strobes ( as and ds ) and the falling edge of e. either of these events can occur first, depending upon the loading on each signal. specificaton #49 indicates the absolute maximum skew that will occur between the rising edge of the strobes and the falling edge of the e clock.
10-16 m68000 8-/16-/32-bit microprocessors user's manual motorola s0 s1 s2 s3 s4 w w wwwwwwwwww s5s6s7s0 a23-a1 clk as r/w e vpa vma data out data in note: this timing diagram is included for those who wish to design their own circuit to generate vma. it shows the best case possible attainable 23 18 41 20 42 51 47 40 43 50 42 41 12 49 18 44 45 41 54 29 27 45 figure 10-6. mc68000 to m6800 peripheral timing diagram (best case) (a pplies to a ll p rocessors e xcept the m c68ec 000)
motorola m68000 8-/16-/32-bit microprocessors user's manual 10-17 10.12 ac electrical specifications ?bus arbitration (v cc =5.0 vdc 5%; gnd=0 vdc, t a =t l to t h ; see figure s 10-7 ?10-11) (applies to all processors except the mc68ec000 ) num characteristic 8 mhz* 10 mhz* 12.5 mhz* 16.67 mhz 12f 16 mhz 20 mhz unit min max min max min max min max min max min max 7 clock high to address, data bus high impedance (maximum) ?0?0?0?0?0?2 ns 16 clock high to control bus high impedance ?0?0?0?0?0?2 ns 33 clock high to bg asserted 62 50 40 0 40 0 30 0 25 ns 34 clock high to bg negated 62 50 40 0 40 0 30 0 25 ns 35 br asserted to bg asserted 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 clks 36 1 br negated to bg negated 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 clks 37 bgack asserted to bg negated 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 clks 37a 2 bgack asserted to br negated 20 1.5 clks 20 1.5 clks 20 1.5 clks 10 1.5 clks 10 1.5 clks 10 1.5 clks clks/ ns 38 bg asserted to control, address, data bus high impedance ( as negated) 80 70 60 50 50 42 ns 39 bg width negated 1.5 1.5 1.5 1.5 1.5 1.5 clks 46 bgack width low 1.5 1.5 1.5 1.5 1.5 1.5 clks 47 asynchronous input setup time 101010???ns 57 bgack negated to as, ds , r/ w driven 1.5 1.5 1.5 1.5 1.5 1.5 clks 57a bgack negated to fc, vma driven 1 1 1 1 1 1 clks 58 1 br negated to as , ds , r/ w driven 1.5 1.5 1.5 1.5 1.5 1.5 clks 58a 1 br negated to fc, vma driven 1 1 1 1 1 1 clks *these specifications represent improvement over previously published specifications for the 8-, 10-, and 12.5-mhz mc68000 and are valid only for product bearing date codes of 8827 and later. ** applies only to the mc68hc000 and mc68hc001. notes: 1. setup time for the synchronous inputs bgack , ipl0 - ipl2 , and vpa guarantees their recognition at the next falling edge of the clock. 2. br need fall at this time only in order to insure being recognized at the end of the bus cycle. 3. timing measurements are referenced to and from a low voltage of 0.8 volt and a high voltage of 2.0 volts, unless otherwise noted. the voltage swing through this range should start outside and pass through the range such that the rise or fall will be lienar between 0.8 volt and 2.0 volts. 4. the processor will negate bg and begin driving the bus again if external arbitration logic negates br before asserting bgack . 5. the minimum value must be met to guarantee proper operation. if the maximum value is exceeded, bg may be reasserted.
10-18 m68000 8-/16-/32-bit microprocessors user's manual motorola 37a 37 46 36 39 34 38 33 35 clk note: setup time to the clock (#47) for the asynchronous inputs berr, bgack, br, dtack, ipl2-ipl0, and vpa guarantees their recognition at the next falling edge of the clock. br bgack bg and r/w strobes figure 10-7. bus arbitration timing (a pplies to a ll p rocessors e xcept the m c68ec 000)
motorola m68000 8-/16-/32-bit microprocessors user's manual 10-19 clk 47 33 35 34 37a 47 47 46 37 57 38 57a br bg bgack as ds vma r/w fc2-fc0 a19-a0 d7-d0 notes: waveform measurements for all inputs and outputs are specified at: logic high 2.0 v, logic low = 0.8 v. 1. mc68008 52-pin version only. 1 figure 10-8. bus arbitration timing (a pplies to a ll p rocessors e xcept the m c68ec 000)
10-20 m68000 8-/16-/32-bit microprocessors user's manual motorola clk 47 33 35 34 37a 47 47 46 37 57 38 57a br bg bgack as ds vma r/w fc2-fc0 a19-a0 d7-d0 notes: waveform measurements for all inputs and outputs are specified at: logic high 2.0 v, logic low = 0.8 v. 1. mc68008 52-pin version only. 1 figure 10-9. bus arbitration timing ?idle bus case (a pplies to a ll p rocessors e xcept the m c68ec 000)
motorola m68000 8-/16-/32-bit microprocessors user's manual 10-21 clk 47 33 35 34 37a 47 47 46 37 57 16 57a br bg bgack as ds vma r/w fc2-fc0 a19-a0 d7-d0 note: waveform measurements for all inputs and outputs are specified at: logic high 2.0 v, logic low = 0.8 v. 1 mc68008 52-pin version only. 7 1 figure 10-10. bus arbitration timing ?active bus case (a pplies to a ll p rocessors e xcept the m c68ec 000)
10-22 m68000 8-/16-/32-bit microprocessors user's manual motorola clk 33 35 37 57a br bg bgack as ds vma r/w fc2-fc0 a19-a0 d7-d0 47 39 39 46 37 46 38 36 58 notes: waveform measurements for all inputs and outputs are specified at: logic high 2.0 v, logic low = 0.8 v. 1. mc68008 52-pin version only. 1 figure 10-11. bus arbitration timing ?multiple bus request (a pplies to a ll p rocessors e xcept the m c68ec 000)
motorola m68000 8-/16-/32-bit microprocessors user's manual 10-23 10.13 mc68ec000 dc electrical specifications (vcc=5.0 vdc 5;pc; gnd=0 vdc; t a = t l to t h ) characteristic symbol min max unit input high voltage v ih 2.0 v cc v input low voltage v il gnd?.3 0.8 v input leakage current berr , br , dtack , clk, ipl2eipl0 , avec @5.25 v mode, halt , reset i in 2.5 20 m a three-state (off state) input current as , a23?0, d15?0, @2.4 v/0.4 v fc2?c0, lds , r/ w , uds i tsi ?0 m a output high voltage as , a23?0, bg , d15?0, (i oh =?00 m a) fc2?c0, lds, r/ w, uds v oh vcc ?.75 v output low voltage (iol = 1.6 ma) halt (iol = 3.2 ma) a23?0, bg , fc2?c0 (iol = 5.0 ma) reset (iol = 5.3 ma) as , d15?0, lds , r/ w, uds v ol 0.5 0.5 0.5 0.5 v current dissipation* f=8 mhz f=10 mhz f=12.5 mhz f=16.67 mhz f= 20 mhz i d 25 30 35 50 70 ma power dissipation f=8 mhz f=10 mhz f=12.5 mhz f=16.67 mhz f=20 mhz p d 0.13 0.16 0.19 0.26 0.38 w capacitance (vin=0 v, ta=25 c, frequency=1 mhz)** c in 20.0 pf load capacitance halt all others c l 70 130 pf * currents listed are with no loading. ** capacitance is periodically sampled rather than 100% tested.
10-24 m68000 8-/16-/32-bit microprocessors user's manual motorola 10.14 mc68ec000 ac electrical specifications ?read and write cycles (vcc=5.0 vdc 5;pc; gnd = 0 vdc; t a = t l to t h ; (s ee figures 10-12 and 10-13) num characteristic 8 mhz 10 mhz 12.5 mhz 16.67 mhz 20 mhz unit min max min max min max min max min max 6 clock low to address valid 35 35 35 30 25 ns 6a clock high to fc valid 35 35 35 30 0 25 ns 7 clock high to address, data bus high impedance (maximum) 55 55 55 50 42 ns 8 clock high to address, fc invalid (minimum) 0 0 0 0 ??s 9 1 clock high to as , ds asserted 3 35 3 35 3 35 3 30 3 25 ns 11 2 address valid to as, ds asserted (read)/ as asserted (write) 30 20 15 15 10 ns 11a 2 fc valid to as, ds asserted (read)/ as asserted (write) 45 45 45 45 40 ns 12 1 clock low to as , ds negated 3 35 3 35 3 35 3 30 3 25 ns 13 2 as, ds negated to address, fc invalid 15 15 15 15 10 ns 14 2 as (and ds read) width asserted 270 195 160 120 100 ns 14a 2 ds width asserted (write) 140 95 80 60 50 ns 15 2 as, ds width negated 150 105 65 60 50 ns 16 clock high to control bus high impedance 55 55 55 50 42 ns 17 2 as, ds negated to r/ w invalid 15 15 15 15 10 ns 18 1 clock high to r/ w high (read) 0 35 0 35 0 35 0 30 0 25 ns 20 1 clock high to r/ w low (write) 0 35 0 35 0 35 0 30 0 25 ns 20a 2,6 as asserted to r/ w low (write) 10 10 10 10 10 ns 21 2 address valid to r/ w low (write) 0 0 0 0 ??s 21a 2 fc valid to r/ w low (write) 60 50 30 30 25 ns 22 2 r/ w low to ds asserted (write) 80 50 30 30 25 ns 23 clock low to data-out valid (write) 35 35 35 30 25 ns 25 2 as, ds negated to data-out invalid (write) 40 30 20 15 10 ns 26 2 data-out valid to ds asserted (write) 40 30 20 15 10 ns 27 5 data-in valid to clock low (setup time on read) 5 5 5 5 ??s 28 2 as , ds negated to dtack negated (asynchronous hold) 0 110 0 110 0 110 0 110 0 95 ns 28a clock high to dtack negated 0 110 0 110 0 110 0 110 0 95 ns
motorola m68000 8-/16-/32-bit microprocessors user's manual 10-25 num characteristic 8 mhz 10 mhz 12.5 mhz 16.67 mhz 20 mhz unit min max min max min max min max min max 29 as, ds negated to data-in invalid (hold time on read) 0 0 0 0 ??s 29a as, ds negated to data-in high impedance 187 150 120 90 75 ns 30 as, ds negated to berr negated 0 0 0 0 ??s 31 2 , 5 dtack asserted to data-in valid (setup time) 90 65 50 50 42 ns 32 halt and reset input transition time 0 150 0 150 0 150 0 150 0 150 ns 33 clock high to bg asserted 35 35 35 0 30 0 25 ns 34 clock high to bg negated 35 35 35 0 30 0 25 ns 35 br asserted to bg asserted 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 clks 36 7 br negated to bg negated 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 clks 38 bg asserted to control, address, data bus high impedance ( as negated) 55 55 55 50 42 ns 39 bg width negated 1.5 1.5 1.5 1.5 1.5 clks 44 as, ds negated to vpa negated 0 55 0 55 0 55 0 50 0 42 ns 47 5 asynchronous input setup time 5 5 5 5 ??s 48 2 , 3 berr asserted to dtack asserted 20 20 20 10 10 ns 53 data-out hold from clock high 0 0 0 0 ??s 55 r/ w asserted to data bus impedance change 30?010 0 ??s 56 4 halt/reset pulse width 10 10 10 10 10 clks 58 7 br negated to as, ds , r/ w driven 1.5 1.5 1.5 1.5 1.5 clks 58a 7 br negated to fc, vma driven 1 1 1 1 1 clks notes:1. for a loading capacitance of less than or equal to 50 pf, subtract 5 ns from the value given in the maximum columns. 2. actual value depends on clock period. 3.i f #47 is satisfied for both dtack and berr , #48 may be ignored. in the absence of dtack, berr is an asynchronous input using the asynchronous input setup time (#47). 4. for power-up, the mc68ec000 must be held in the reset state for 520 clocks to allow stabilization of on- chip circuitry. after the system is powered up, #56 refers to the minimum pulse width required to reset the processor. 5. if the asynchronous input setup time (#47) requirement is satisfied for dtack , the dtack -asserted to data setup time (#31) requirement can be ignored. the data must only satisfy the data-in to clock low setup time (#27) for the following clock cycle. 6. when as and r/ w are equally loaded ( 20;pc), subtract 5 ns from the values given in these columns. 7. the minimum value must be met to guarantee proper operation. if the maximum value is exceeded, bg may be reasserted. 8. ds is used in this specification to indicate uds and lds .
10-26 m68000 8-/16-/32-bit microprocessors user's manual motorola 6a 8 6 13 14 12 17 18 47 28 29 27 48 47 30 47 32 56 47 32 s0 s1 s2 s3 s4 s5 s6 clk fc2?c0 a23?0 as lds / uds r/w dtack data in berr / br (note 2) halt / reset 47 asynchronous inputs (note 1) s7 31 7 11 11a notes: 1. setup time for the asynchronous inputs ipl2?pl0 and avec (#47) guarantees their recognition at the next falling edge of the clock. 2. br need fall at this time only to insure being recognized at the end of the bus cycle. 3. timing measurements are referenced to and from a low voltage of 0.8 v and a high voltage of 2.0 v, unless otherwise noted. the voltage swing through this range should start outside and pass through the range such that the rise or fall is linear between 0.8 v and 2.0 v. 9 15 figure 10-12. mc68ec000 read cycle timing diagram
motorola m68000 8-/16-/32-bit microprocessors user's manual 10-27 6a 8 6 15 13 9 14 12 17 18 47 28 25 26 48 47 30 47 32 56 47 32 s0 s1 s2 s3 s4 s5 s6 clk fc2-fc0 a23-a0 as lds / uds r/w dtack data out berr / br (note 2) halt / reset 47 asynchronous inputs (note 1) s7 notes: 1. timing measurements are referenced to and from a low voltage of 0.8 v and a high voltage of 2.0 v, unless otherwise noted. the voltage swing through this range should start outside and pass through the range such that the rise or fall is linear between 0.8 v and 2.0 v. 2. because of loading variations, r/w may be valid after as even though both are initiated by the rising edge of s2 (specification #20a). 23 21a 7 11 11a 9 14a 53 7 55 21 22 20a 20 figure 10-13. mc68ec000 write cycle timing diagram
10-28 m68000 8-/16-/32-bit microprocessors user's manual motorola 10.15 mc68ec000 ac electrical specifications?us arbitration (vcc=5.0vdc 5%; gnd=0 vdc; t a = t l to t h ; see figure 10-14) num characteristic 8 mhz 10 mhz 12.5 mhz 16.67 mhz 20 mhz unit min max min max min max min max min max 7 clock high to address, data bus high impedance (maximum) 55 55 55 50 42 ns 16 clock high to control bus high impedance 55 55 55 50 42 ns 33 clock high to bg asserted 35 35 35 0 30 0 25 ns 34 clock high to bg negated 35 35 35 0 30 0 25 ns 35 br asserted to bg asserted 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 clks 36 7 br negated to bg negated 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 1.5 3.5 clks 38 bg asserted to control, address, data bus high impedance ( as negated) 55 55 55 50 42 ns 39 bg width negated 1.5 1.5 1.5 1.5 1.5 clks 47 asynchronous input setup time 55?55ns 58 1 br negated to as , ds , r/ w driven 1.5 1.5 1.5 1.5 1.5 clks 58a 1 br negated to fc driven 1 1 1 1 1 clks notes: 1.the minimum value must be met to guarantee proper operation. if the maximum value is exceeded, bg may be reasserted. 2. ds is used in this specification to indicate uds and lds .
motorola m68000 8-/16-/32-bit microprocessors user's manual 10-29 36 clk 47 33 35 34 58 58a br bg as ds r/w fc2-fc0 a19-a0 d7-d0 notes: waveform measurements for all inputs and outputs are specified at: logic high 2.0 v, logic low = 0.8 v. 38 39 figure 10-14. mc68ec000 bus arbitration timing diagram
motorola m68000 8-/16-/32-bit microprocessors user's manual 11-1 section 11 ordering information and mechanical data this section provides pin assignments and package dimensions for the devices described in this manual. 11.1 pin assignments package 68000 68008 68010 68hc000 68hc001 68ec000 64-pin dual-in-line 444 68-terminal pin grid array 4444 64-lead quad pack 4 68-lead quad flat pack 4 4444 52-lead quad 4 48-pin dual-in-line 4
11-2 m68000 8-/16-/32-bit microprocessors user's manual motorola clk d5 d6 d7 d8 d9 d10 d11 d12 d13 d14 d15 gnd a23 a22 a21 v cc a20 a19 a18 a17 a16 a15 a14 a13 a12 a11 a10 a9 a8 a7 a6 a5 d4 d3 d2 d1 d0 as uds lds r/w dtack bg bgack br v cc gnd halt reset vma e vpa berr ipl2 ipl0 ipl1 fc2 fc1 fc0 a1 a2 a3 a4 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 46 47 45 44 43 42 41 40 39 38 37 36 35 34 33 mc68000 MC68010 mc68hc000 figure 11-1. 64-pin dual in line
motorola m68000 8-/16-/32-bit microprocessors user's manual 11-3 nc e vma halt clk br bgack dtack nc fc2 reset gnd v cc bg as fc0 fc1 r/w uds d1 a1 nc d0 d2 a3 a2 a4 a5 a6 a8 a7 a10 a13 d3 d4 d6 d5 d9 d7 d11 d8 d13 a9 a11 a12 a15 a18 v cc gnd a23 d14 d10 nc a14 a16 a17 a19 a20 a21 a22 d15 d12 berr ipl0 ipl2 ipl1 vpa (bottom view) 1 234 5678910 a b c d e f g h j k lds mc68000/MC68010/mc68hc000 mode e vma halt clk br bgack dtack nc fc2 reset gnd v cc bg as fc0 fc1 r/w uds d1 a1 nc d0 d2 a3 a2 a4 a5 a6 a8 a7 a10 a13 d3 d4 d6 d5 d9 d7 d11 d8 d13 a9 a11 a12 a15 a18 v cc gnd a23 d14 d10 nc a14 a16 a17 a19 a20 a21 a22 d15 d12 berr ipl0 ipl2 ipl1 vpa (bottom view) 1 234 5678910 a b c d e f g h j k lds mc68hc001 figure 11-2. 68-lead pin grid array
11-4 m68000 8-/16-/32-bit microprocessors user's manual motorola gnd a19 a18 a17 a16 a15 a14 a13 v cc gnd d13 d14 d15 a20 a21 a23 a22 d5 d6 d7 d4 d3 d2 d1 d0 as r/w lds uds d8 d9 d10 d11 d12 a12 a11 a10 a9 a8 a7 a6 a5 fc2 fc1 fc0 a1 a2 a3 a4 nc ipl0 clk e dtack bg br halt reset vpa berr ipl1 v cc gnd gnd ipl2 vma bgack nc 1 10 18 26 27 44 43 35 968 60 52 61 mc68000/mc68hc000/MC68010 gnd a18 a17 a16 a15 a14 a13 a12 v cc d13 d14 d15 a19 a21 a23 a22 d5 d6 d7 d4 d3 d2 d1 d0 as r/w lds uds d8 d9 d10 d11 d12 a0 a11 a10 a9 a8 a7 a6 a5 fc2 fc1 fc0 a1 a2 a3 a4 ipl0 clk nc dtack bg br halt reset avec berr ipl1 v cc gnd gnd ipl2 bgack mode 1 10 18 26 27 44 43 35 968 60 52 61 mc68ec000 gnd a20 gnd figure 11-3. 68-lead quad pack (1 of 2)
motorola m68000 8-/16-/32-bit microprocessors user's manual 11-5 gnd a19 a18 a17 a16 a15 a14 a13 v cc gnd d13 d14 d15 a20 a21 a23 a22 d5 d6 d7 d4 d3 d2 d1 d0 as r/w lds uds d8 d9 d10 d11 d12 a12 a11 a10 a9 a8 a7 a6 a5 fc2 fc1 fc0 a1 a2 a3 a4 nc ipl0 clk e dtack bg br halt reset vpa berr ipl1 v cc gnd gnd ipl2 vma bgack mode 1 10 18 26 27 44 43 35 968 60 52 61 mc68hc001 figure 11-3. 68-lead quad pack (2 of 2) clk e gnd fc0 fc1 fc2 a0 a1 a2 a3 a4 a5 a8 a7 a6 ipl0 a18 a9 a10 a12 gnd a16 a13 cc v a14 a17 a11 a15 1 8 20 21 34 33 752 46 47 d0 d1 d2 d3 d4 d5 d6 a19 a20 d7 r/w ds as bgack bg dtack br halt reset vpa berr ipl1 ipl2 mc68008 21 a figure 11-4. 52-lead quad pack
11-6 m68000 8-/16-/32-bit microprocessors user's manual motorola gnd a1 a0 fc0 fc1 fc2 e gnd clk d0 d1 d2 a3 a4 a5 a6 a7 a8 a9 a10 a11 a12 a13 a14 v cc a16 a17 a18 a19 d7 d6 d5 d4 d3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 30 31 29 28 27 26 25 a2 a15 reset halt as ds r/w dtack bg br vpa berr ipl1 ipl2/ipl0 mc68008 figure 11-5. 48-pin dual in line
motorola m68000 8-/16-/32-bit microprocessors user's manual 11-7 a19 a18 a17 a16 a15 a14 a13 v cc d13 d14 d15 a20 a21 a23 a22 d5 d6 d7 d4 d3 d2 d1 d0 as r/w lds uds d8 d9 d10 d11 d12 a12 a11 a10 a9 a8 a7 a6 a5 fc0 a0 a1 a3 gnd a4 a2 fc1 clk dtack bg br halt reset berr ipl1 v cc mode gnd ipl2 avec 1 16 17 33 32 64 48 49 ipl0 fc2 gnd mc68ec000 figure 11-6. 64-lead quad flat pack 11.2 package dimensions case package 68000 68008 68010 68hc000 68hc001 68ec000 740-03 l suffix 4 767-02 p suffix 4 746-01 lc suffix 444 754-01 r and p suffix 444 765a-05 rc suffix 4444 778-02 fn suffix 4 779-02 fn suffix 44 779-01 fn suffix 44 4 847-01 fc suffix 4 840b-01 fu suffix 4
11-8 m68000 8-/16-/32-bit microprocessors user's manual motorola 64 32 1 b f g d c n k m l j l suffix 746-03 notes: 1. dimension -a- is datum. 2. postional tolerance for leads: 4. dimension "l" to center of leads when formed parallel. 3. -t- is seating plane 5. dimensioning and tolerancing per ansi y14.5m, 1982. dim millimeters inches min max min max a b c d f g j k l m n 60.36 61.56 2.376 2.424 14.64 15.34 0.576 0.604 3.05 4.32 0.120 0.160 3.81 0.533 0.015 0.021 .762 1.397 0.030 0.055 2.54 bsc 0.100 bsc 0.204 0.330 0.008 0.013 2.54 4.19 0.100 0.165 0 10 0 10 1.016 1.524 0.040 0.060 33 a t m 0.25 (0.010) t a m 15.24 bsc 0.600 bsc figure 11-7. case 740-03? suffix
motorola m68000 8-/16-/32-bit microprocessors user's manual 11-9 48 24 1 a b f gd c n k m l j p suffix 767-02 h notes: 1. -r- is end of package datum plane -t- is both a datum and seating plane 2. positional tolerance for leads 1 and 48. 3. dimension "a" and "b" does not include mold flash, maximum mold flash 0.25 (0.010). 4. dimension "l" is to center of leads when formed parallel. 5. dimensioning and tolerancing per ansi y14.5, 1982. 6. controlling dimension: inch. dim millimeters inches min max min max a b c d f g h j k l m n 61.34 62.10 2.415 2.445 13.72 14.22 0.540 0.560 3.94 5.08 0.155 0.200 0.36 0.55 0.014 0.022 1.02 1.52 0.040 0.060 2.54 bsc 0.100 bsc 0.20 0.38 0.008 0.015 2.92 3.81 0.115 0.135 15.24 bsc 0.600 bsc 015015 0.51 1.02 0.020 0.040 1.79 bsc 0.070 bsc 25 r t m 0.51 (0.020) t b r positional tolerance for lead pattern; m 0.25 (0.020) t b figure 11-8. case 767-02? suffix
11-10 m68000 8-/16-/32-bit microprocessors user's manual motorola 64 32 1 b f g d c n k m l j l suffix 746-01 notes: 1. dimension -a- is datum. 2. postional tolerance for leads: 4. dimension "l" to center of leads when formed parallel. 3. -t- is seating plane 5. dimensioning and tolerancing per ansi y14.5, 1973. dim millimeters inches min max min max a b c d f g j k l m n 80.52 82.04 3.170 3.230 22.25 22.96 0.876 0.904 3.05 4.32 0.120 0.160 0.38 0.53 0.015 0.021 .76 1.40 0.030 0.055 2.54 bsc 0.100 bsc 0.20 0.33 0.008 0.013 2.54 4.19 0.100 0.165 22.61 0.890 0 10 0 10 1.02 1.52 0.040 0.060 33 a t 23.11 0.910 m 0.25 (0.010) t a m figure 11-9. case 746-01?c suffix
motorola m68000 8-/16-/32-bit microprocessors user's manual 11-11 64 32 1 a b f g d c n k m l j p suffix 754-01 notes: 1. dimensions a and b are datums. 3. positional tolerance for leads (dimension d): 4. dimension b does not includemold flash. 5. dimension l is to center of leads when formed parallel. 6. dimensioning and tolerancing per ansi y14.5, 1982. dim millimeters inches min max min max a b c d f g j k l m n 81.16 81.91 3.195 3.225 20.17 20.57 0.790 0.810 4.83 5.84 0.190 0.230 0.33 0.53 0.013 0.021 1.27 1.77 0.050 0.070 2.54 bsc 0.100 bsc 0.20 0.38 0.008 0.015 3.05 3.55 0.120 0.140 22.86 bsc 0.9 00 bsc 015015 0.51 1.02 0.020 0.040 33 t 2. -t- is seating plane. m 0.25 (0.010) t a m m b figure 11-10. case 754-01? and p suffix
11-12 m68000 8-/16-/32-bit microprocessors user's manual motorola figure 11-11. case 765a-05?c suffix
motorola m68000 8-/16-/32-bit microprocessors user? manual a- 1 appendix a MC68010 loop mode operation in the loop mode of the MC68010, a single instruction is executed repeatedly under control of the test condition, decrement, and branch (dbcc) instruction without any instruction fetch bus cycles. the execution of a single-instruction loop without fetching an instruction provides a highly efficient means of repeating an instruction because the only bus cycles required are those that read and write the operands. the dbcc instruction uses three operands: a loop counter, a branch condition, and a branch displacement. when this instruction is executed in the loop mode, the value in the low-order word of the register specified as the loop counter is decremented by one and compared to minus one. if the result after decrementing the value is equal to minus one, the result is placed in the loop counter, and the next instruction in sequence is executed. otherwise, the condition code register is checked against the specified branch condition. if the branch condition is true, the result is discarded, and the next instruction in sequence is executed. when the count is not equal to minus one and the branch condition is false, the branch displacement is added to the value in the program counter, and the instruction at the resulting address is executed. figure a-1 shows the source code of a program fragment containing a loop that executes in the loop mode in the MC68010. the program moves a block of data at address source to a block starting at address dest. the number of words in the block is labeled length. if any word in the block at address source contains zero, the move operation stops, and the program performs whatever processing follows this program fragment. loop lea lea move.w move.w dbeq source, a0 dest, a1 #length, d0 (a0);pl, (a1)+ d0, loop load a pointer to source data load a pointer to destination load the counter register loop to move the block of data stop if data word is zero figure a-1. dbcc loop mode program example the first load effective address (lea) instruction loads the address labeled source into address register a0. the second instruction, also an lea instruction, loads the address labeled dest into address register a1. next, a move data from source to destination (move) instruction moves the number of words into data register d0, the loop counter. the last two instructions, a move and a test equal, decrement, and branch (dbeq), form the loop that moves the block of data. the bus activity required to execute these instructions consists of the following cycles:
a- 2 m68000 8-/16-/32-bit microprocessors user? manual motorola 1. fetch the move instruction. 2. fetch the dbeq instruction. 3. read the operand at the address in a0. 4. write the operand at the address in a1. 5. fetch the displacement word of the dbeq instruction. of these five bus cycles, only two move the data. however, the MC68010 has a two-word prefetch queue in addition to the one-word instruction decode register. the loop mode uses the prefetch queue and the instruction decode register to eliminate the instruction fetch cycles. the processor places the move instruction in the instruction decode register and the two words of the dbeq instruction in the prefetch queue. with no additional opcode fetches, the processor executes these two instructions as required to move the entire block or to move all nonzero words that precede a zero. the MC68010 enters the loop mode automatically when the conditions for loop mode operation are met. entering the loop mode is transparent to the programmer. the conditions are that the loop count and branch condition of the dbcc instruction must result in looping, the branch displacement must be minus four, and the branch must be to a one- word loop mode instruction preceding the dbcc instruction. the looped instruction and the first word of the dbcc instruction are each fetched twice when the loop is entered. when the processor fetches the looped instruction the second time and determines that the looped instruction is a loop mode instruction, the processor automatically enters the loop mode, and no more instruction fetches occur until the count is exhausted or the loop condition is true. in addition to the normal termination conditions for the loop, several abnormal conditions cause the MC68010 to exit the loop mode. these abnormal conditions are as follows: interrupts trace exceptions reset operations bus errors any pending interrupt is taken after each execution of the dbcc instruction, but not after each execution of the looped instruction. taking an interrupt exception terminates the loop mode operation; loop mode operation can be restarted on return from the interrupt handler. while the t bit is set, a trace exception occurs at the end of both the looped instruction and the dbcc instruction, making loop mode unavailable while tracing is enabled. a reset operation aborts all processing, including loop mode processing. a bus error during loop mode operation is handled the same as during other processing; however, when the return from exception (rte) instruction continues execution of the looped instruction, the three-word loop is not fetched again. table a-1 lists the loop mode instructions of the MC68010. only one-word versions of these instructions can operate in the loop mode. one-word instructions use the three address register indirect modes: (an), (an)+, and ?an).
motorola m68000 8-/16-/32-bit microprocessors user? manual a- 3 table a-1. MC68010 loop mode instructions opcodes applicable addressing modes move [bwl] (ay) to (ax) (ay) to (ax)+ (ay) to ?ax) (ay)+ to (ax) (ay)+ to ?ax) ?ay) to (ax) ?ay) to (ax)+ ?ay) to ?ax) ry to (ax) ry to (ax)+ add [bwl] and [bwl] cmp [bwl] or [bwl] sub [bwl] (ay) to dx (ay)+ to dx ?ay) to dx adda [wl] cmpa [wl] suba [wl] (ay) to ax ?ay) to ax (ay)+ to ax add [bwl] and [bwl] eor [bwl] or [bwl] sub [bwl] dx to (ay) dx to (ay)+ dx to ?ay) abcd [b] addx [bwl] sbcd [b] subx [bwl] ?ay) to ?ax) cmp [bwl] (ay)+ to (ax)+ clr [bwl] neg [bwl] negx [bwl} not [bwl] tst [bwl] nbcd [b] (ay) (ay)+ ?ay) asl [w] asr [w] lsl [w] lsr [w] rol [w] ror [w] roxl [w] roxr (ay) by #1 (ay)+ by #1 ?ay) by #1 note: [b, w, or l] indicate an operand size of byte, word, or long word.

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