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MC68000 INSTRUCTION EXECUTION TIMES

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 · 10 months ago

MC68000 INSTRUCTION EXECUTION TIMES 


( TAB-SIZE = 4 )
In this data it is assumed that both read and write cycle times are four clock periods.
The number of read or write cycles isenclosed in parenthesis (R/W) following the number
of clock periods. Any questions/suggestions or... -> contact me:

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TABLE 1 EFFECTIVE ADDRESS CALCULATION TIMES

-----------------------------------------------------------------------------------------
| Addressing Mode | Word | Long |
-----------------------------------------------------------------------------------------
| Dn | Data Register Direct | 0(0/0) |0(0/0) |
| An | Address Register Direct | 0(0/0) |0(0/0) |
-----------------------------------------------------------------------------------------
| (An) | Address Register Indirect | 4(1/0) |8(2/0) |
| (An)+ | Address Register Indirect with Postincreament | 4(1/0) |8(2/0) |
-----------------------------------------------------------------------------------------
| -(An) | Address Register Indirect with Predecreament | 6(1/0) |10(2/0)|
| d(An) | Address Register Indirect with Displacement | 8(2/0) |12(3/0)|
-----------------------------------------------------------------------------------------
| d(An, Rn)* | Address Register Indirect with Index | 10(2/0) |14(3/0)|
| xxx.W | Absolute Short | 8(2/0) |12(3/0)|
-----------------------------------------------------------------------------------------
| xxx.L | Absolute Long | 12(3/0) |16(4/0)|
| d(PC) | Program Counter with Displacement | 8(2/0) |12(3/0)|
-----------------------------------------------------------------------------------------
| d(PC, Rn)* | Program counter with Index | 10(2/0) |14(3/0)|
| #xxx | Immediate | 4(1/0) | 8(2/0)|
-----------------------------------------------------------------------------------------
* The size of the index register does not affect execution time

TABLE 2 MOVE BYTE AND WORD INSTRUCTION EXECUTION TIMES

-----------------------------------------------------------------------------------------
| Source | Destination |
| | Dn | An | (An) | (An)+ | -(An) | d(An) |d(An,R)| xxx.W | xxx.L |
-----------------------------------------------------------------------------------------
| Dn | 4(1/0)| 4(1/0)| 8(1/1)| 8(1/1)| 8(1/1)|12(2/1)|14(2/1)|12(2/1)|16(3/1)|
| An | 4(1/0)| 4(1/0)| 8(1/1)| 8(1/1)| 8(1/1)|12(2/1)|14(2/1)|12(2/1)|16(3/1)|
| (An) | 8(2/0)| 8(2/0)|12(2/1)|12(2/1)|12(2/1)|16(3/1)|18(3/1)|16(3/1)|20(4/1)|
-----------------------------------------------------------------------------------------
| (An)+ | 8(2/0)| 8(2/0)|12(2/1)|12(2/1)|12(2/1)|16(3/1)|18(3/1)|16(3/1)|20(4/1)|
| -(An) |10(2/0)|10(2/0)|14(2/1)|14(2/1)|14(2/1)|18(3/1)|20(3/1)|18(3/1)|22(4/1)|
| d(An) |12(3/0)|12(3/0)|16(3/1)|16(3/1)|16(3/1)|20(4/1)|22(4/1)|20(4/1)|24(5/1)|
-----------------------------------------------------------------------------------------
| d(An, Rn)* |14(3/0)|14(3/0)|18(3/1)|18(3/1)|18(3/1)|22(4/1)|24(4/1)|22(4/1)|26(5/1)|
| xxx.W |12(3/0)|12(3/0)|16(3/1)|16(3/1)|16(3/1)|20(4/1)|22(4/1)|20(4/1)|24(5/1)|
| xxx.L |16(4/0)|16(4/0)|20(4/1)|20(4/1)|20(4/1)|24(5/1)|26(5/1)|24(5/1)|28(6/1)|
-----------------------------------------------------------------------------------------
| d(PC) |12(3/0)|12(3/0)|16(3/1)|16(3/1)|16(3/1)|20(4/1)|22(4/1)|20(4/1)|24(5/1)|
| d(PC, Rn)* |14(3/0)|14(3/0)|18(3/1)|18(3/1)|18(3/1)|22(4/1)|24(4/1)|22(4/1)|26(5/1)|
| #xxx | 8(2/0)| 8(2/0)|12(2/1)|12(2/1)|12(2/1)|16(3/1)|18(3/1)|16(3/1)|20(4/1)|
-----------------------------------------------------------------------------------------
* The size of the index register does not affect execution time

TABLE 3 MOVE LONG INSTRUCTION EXECUTION TIMES

-----------------------------------------------------------------------------------------
| Source | Destination |
| | Dn | An | (An) | (An)+ | -(An) | d(An) |d(An,R)| xxx.W | xxx.L |
-----------------------------------------------------------------------------------------
| Dn | 4(1/0)| 4(1/0)|12(1/2)|12(1/2)|12(1/2)|16(2/2)|18(2/2)|16(2/2)|20(3/2)|
| An | 4(1/0)| 4(1/0)|12(1/2)|12(1/2)|12(1/2)|16(2/2)|18(2/2)|16(2/2)|20(3/2)|
| (An) |12(3/0)|12(3/0)|20(3/2)|20(3/2)|20(3/2)|24(4/2)|26(4/2)|24(4/2)|28(5/2)|
-----------------------------------------------------------------------------------------
| (An)+ |12(3/0)|12(3/0)|20(3/2)|20(3/2)|20(3/2)|24(4/2)|26(4/2)|24(4/2)|28(5/2)|
| -(An) |14(3/0)|14(3/0)|22(3/2)|22(3/2)|22(3/2)|26(4/2)|28(4/2)|26(4/2)|30(5/2)|
| d(An) |16(4/0)|16(4/0)|24(4/2)|24(4/2)|24(4/2)|28(5/2)|30(5/2)|28(5/2)|32(6/2)|
-----------------------------------------------------------------------------------------
| d(An, Rn)* |18(4/0)|18(4/0)|26(4/2)|26(4/2)|26(4/2)|30(5/2)|32(5/2)|30(5/2)|34(6/2)|
| xxx.W |16(4/0)|16(4/0)|24(4/2)|24(4/2)|24(4/2)|28(5/2)|30(5/2)|28(5/2)|32(6/2)|
| xxx.L |20(5/0)|20(5/0)|28(5/2)|28(5/2)|28(5/2)|32(6/2)|34(6/2)|32(6/2)|36(7/2)|
-----------------------------------------------------------------------------------------
| d(PC) |16(4/0)|16(4/0)|24(4/2)|24(4/2)|24(4/2)|28(5/2)|30(5/2)|28(5/2)|32(5/2)|
| d(PC, Rn)* |18(4/0)|18(4/0)|26(4/2)|26(4/2)|26(4/2)|30(5/2)|32(5/2)|30(5/2)|34(6/2)|
| #xxx |12(3/0)|12(3/0)|20(3/2)|20(3/2)|20(3/2)|24(4/2)|26(4/2)|24(4/2)|28(5/2)|
-----------------------------------------------------------------------------------------
* The size of the index register does not affect execution time

TABLE 4 STANDART INSTRUCTION EXECUTION TIMES

---------------------------------------------------------
|Instruction| Size |op<ea>,An^ | op<ea>,Dn | op Dn,<M> |
---------------------------------------------------------
| ADD | Word | 8(1/0)+ | 4(1/0)+ | 8(1/1)+ |
| | Long | 6(1/0)+** | 6(1/0)+** | 12(1/2)+ |
---------------------------------------------------------
| AND | Word | - | 4(1/0)+ | 8(1/1)+ |
| | Long | - | 6(1/0)+** | 12(1/2)+ |
---------------------------------------------------------
| CMP | Word | 6(1/0)+ | 4(1/0)+ | - |
| | Long | 6(1/0)+ | 6(1/0)+ | - |
---------------------------------------------------------
| DIVS | - | - |158(1/0)+* | - |
| DIVU | - | - |140(1/0)+* | - |
---------------------------------------------------------
| EOR | Word | - | 4(1/0)*** | 8(1/1)+ |
| | Long | - | 8(1/0)*** | 12(1/2)+ |
---------------------------------------------------------
| MULS | - | - | 70(1/0)+* | - |
| MULU | - | - | 70(1/0)+* | - |
---------------------------------------------------------
| OR | Word | - | 4(1/0)+ | 8(1/1)+ |
| | Long | - | 6(1/0)+** | 12(1/2)+ |
---------------------------------------------------------
| SUB | 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 value
** The base time of 6cc is increased to eight if the effective
address mode is register direct or immediate
*** 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 <ea>
MULS:n=concatanate the <ea> 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.

TABLE 5 IMMEDIATE INSTRUCTION EXECUTION TIMES

---------------------------------------------------------
|Instruction| Size | op #,Dn | op #,An | op #,M |
---------------------------------------------------------
| ADDI | Word | 8(2/0) | - | 12(2/1)+ |
| | Long | 16(3/0) | - | 20(3/2)+ |
---------------------------------------------------------
| ADDQ | Word | 4(1/0) | 8(1/0)* | 8(1/1)+ |
| | Long | 8(1/0) | 8(1/0) | 12(1/2)+ |
---------------------------------------------------------
| ANDI | Word | 8(2/0) | - | 12(2/1)+ |
| | Long | 16(3/0) | - | 20(3/1)+ |
---------------------------------------------------------
| CMPI | Word | 8(2/0) | - | 8(2/0)+ |
| | Long | 14(3/0) | - | 12(3/0)+ |
---------------------------------------------------------
| EORI | Word | 8(2/0) | - | 12(2/1)+ |
| | Long | 16(3/0) | - | 20(3/2)+ |
---------------------------------------------------------
| MOVEQ | Long | 4(1/0) | - | - |
---------------------------------------------------------
| ORI | Word | 8(2/0) | - | 12(2/1)+ |
| | Long | 16(3/0) | - | 20(3/2)+ |
---------------------------------------------------------
| SUBI | Word | 8(2/0) | - | 12(2/1)+ |
| | Long | 16(3/0) | - | 20(3/2)+ |
---------------------------------------------------------
| SUBQ | Word | 4(1/0) | 8(1/0)* | 8(1/1)+ |
| | Long | 8(1/0) | 8(1/0) | 12(1/2)+ |
---------------------------------------------------------
+ Add effective address calculation time
* Word only

TABLE 6 SINGLE OPERAND INSTRUCTION EXECUTION TIMES

---------------------------------------------
|Instruction| Size | Register | Memory |
---------------------------------------------
| CLR | Word | 4(1/0) | 8(1/1)+ |
| | Long | 6(1/0) | 12(1/2)+ |
---------------------------------------------
| NBCD | Byte | 6(1/0) | 8(1/1)+ |
---------------------------------------------
| NEG | Word | 4(1/0) | 8(1/1)+ |
| | Long | 6(1/0) | 12(1/2)+ |
---------------------------------------------
| NEGX | Word | 4(1/0) | 8(1/1)+ |
| | Long | 6(1/0) | 12(1/2)+ |
---------------------------------------------
| NOT | Word | 4(1/0) | 8(1/1)+ |
| | Long | 6(1/0) | 12(1/2)+ |
---------------------------------------------
| Scc |Byte,F | 4(1/0) | 8(1/1)+ |
| |Byte,T | 6(1/0) | 8(1/1)+ |
---------------------------------------------
| TAS | Byte | 4(1/0) | 10(1/1)+ |
---------------------------------------------
| TST | Word | 4(1/0) | 4(1/0)+ |
| | Long | 4(1/0) | 4(1/0)+ |
---------------------------------------------
+ Add effective address calculation time

TABLE 7 SHIFT/ROTATE INSTRUCTION EXECUTION TIMES

---------------------------------------------
|Instruction| Size | Register | Memory |
---------------------------------------------
| ASR, ASL | Word | 6+2n(1/0) | 8(1/1)+ |
| | Long | 8+2n(1/0) | - |
---------------------------------------------
| LSR, LSL | Word | 6+2n(1/0) | 8(1/1)+ |
| | Long | 8+2n(1/0) | - |
---------------------------------------------
| ROR, ROL | Word | 6+2n(1/0) | 8(1/1)+ |
| | Long | 8+2n(1/0) | - |
---------------------------------------------
| ROXR,ROXL | Word | 6+2n(1/0) | 8(1/1)+ |
| | Long | 8+2n(1/0) | - |
---------------------------------------------
+ Add effective address calculation time
n Is the shift count

TABLE 8 BIT MANIPULATION INSTRUCTION EXECUTION TIMES

---------------------------------------------------------------------
|Instruction| Size | Dynamic | Static |
| | | 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

TABLE 9 CONDITIONAL INSTRUCTION EXECUTION TIMES

-------------------------------------------------
|Instruction|Displace- | Branch | Branch |
| | ment | Taken | 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 | Byte | - | 12(2/0) |
| | Word | 10(2/0) | 14(3/0) |
-------------------------------------------------
+ Add effective address calculation time
* Indicates maximum value

TABLE 10 JMP, JSR, LEA, PEA AND MOVEM INSTRUCTION EXECUTION TIMES

------------------------------------------------------------------------------------------
|INSTR | SIZE | (An) | (An)+ | -(An) | d(An) |d(A,R)*| xxx.W | xxx.L | d(PC) |d(PC,R)*|
------------------------------------------------------------------------------------------
| 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)|
------------------------------------------------------------------------------------------
| | Word | 12+4n | 12+4n | - | 16+4n | 18+4n | 16+4n | 20+4n | 16+4n | 18+4n |
| MOVEM | | (3+n) | (3+n) | - | (4+n) | (4+n) | (4+n) | (5+n) | (4+n) | (4+n) |
| |---------------------------------------------------------------------------------
| M->R | Long | 12+8n | 12+8n | - | 16+8n | 18+8n | 16+8n | 20+8n | 16+8n | 18+8n |
| | |(3+2n) |(3+2n) | - | (4+2n)| (4+2n)| (4+2n)| (5+2n)| (4+2n)| (4+2n) |
------------------------------------------------------------------------------------------
| | Word | 8+4n | - | 8+4n | 12+4n | 14+4n | 12+4n | 16+4n | - | - |
| MOVEM | | (2/n) | - | (2/n) | (3/n) | (3/n) | (3/n) | (4/n) | - | - |
| |---------------------------------------------------------------------------------
| R->M | Long | 8+8n | - | 8+8n | 12+8n | 14+8n | 12+8n | 16+8n | - | - |
| | | (2/2n)| - | (2/2n)| (3/2n)| (3/2n)| (3/2n)| (4/2n)| - | - |
------------------------------------------------------------------------------------------
n Is the number of registers to move
* The size of the index register does not affect execution time


TABLE 11 MULTI-PRECISION 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(5/2) |
-------------------------------------------------
| 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) |
-------------------------------------------------

TABLE 12 MISCELLANEOUS INSTRUCTION EXECUTION TIMES

-------------------------------------------------
|Instruction| Size | Register | Memory |
-------------------------------------------------
|ANDI TO CCR| Byte | 20(3/0) | - |
-------------------------------------------------
|ANDI TO SR | Word | 20(3/0) | - |
-------------------------------------------------
| CHK | - | 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 SR -> | - | 6(1/0) | 8(1/1)+ |
-------------------------------------------------
|MOVE -> CCR| - | 12(2/0) | 12(2/0)+ |
-------------------------------------------------
|MOVE -> 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 USP ->| - | 4(1/0) | - |
-------------------------------------------------
|MOVE -> USP| - | 4(1/0) | - |
-------------------------------------------------
| NOP | - | 4(1/0) | - |
-------------------------------------------------
| RESET | - | 132(1/0) | - |
-------------------------------------------------
| RTE | - | 20(5/0) | - |
-------------------------------------------------
| RTR | - | 20(5/0) | - |
-------------------------------------------------
| RTS | - | 16(4/0) | - |
-------------------------------------------------
| STOP | - | 4(1/0) | - |
-------------------------------------------------
| SWAP | - | 4(1/0) | - |
-------------------------------------------------
| TRAPV | - | 4(1/0) | - |
-------------------------------------------------
| UNLK | - | 12(3/0) | - |
-------------------------------------------------
+ Add effective address calculation time


TABLE 13 MOVE PHERIPHERAL INSTRUCTION EXECUTION TIMES

-------------------------------------------------
|Instruction| Size | Reg->Mem | Mem->Reg |
-------------------------------------------------
| MOVEP | Word | 16(2/2) | 16(4/0) |
| | Long | 24(2/4) | 24(6/0) |
-------------------------------------------------

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