Immediate Instruction Execution Times - Motorola M68000 User Manual

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
ADD/ADDA
AND
CMP/CMPA
DIVS
DIVU
EOR
MULS
MULU
OR
SUB
+ 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
MULS, MULU — The multiply algorithm requires 42+2n clocks where n is defined as:

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
7-4 M68000 8-/16-/32-BIT MICROPROCESSORS USER'S MANUAL
Freescale Semiconductor, Inc.
Size op<ea>, An
Byte —
Word 12(2/0)+
Long 10(2/0)+**
—
Byte
Word —
Long —
Byte —
Word 10(2/0)+
Long 10(2/0)+
— —
— —
Byte, —
Word, —
Long —
— —
— —
Byte, —
Word —
Long —
Byte,
Word 12(2/0)+
Long 10(2/0)+**
between the best- and worst-case timings.
MULS: n = tag the <ea> 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 <ea>
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op<ea>, Dn op Dn, <M>
8(2/0)+ 12(2/1)+
8(2/0)+ 16(2/2)+
10(2/0)+** 24(2/4)+
8(2/0)+ 12(2/1)+
8(2/0)+ 16(2/2)+
10(2/0)+** 24(2/4)+
8(2/0)+ —
8(2/0)+ —
10(2/0)+ —
162(2/0)+* —
144(2/0)+* —
8(2/0)+*** 12(2/1)+
8(2/0)+*** 16(2/2)+
12(2/0)+*** 24(2/4)+
74(2/0)+* —
74(2/0)+* —
8(2/0)+ 12(2/1)+
8(2/0)+ 16(2/2)+
10(2/0)+** 24(2/4)+
8(2/0)+ 12(2/1)+
8(2/0)+ 16(2/2)+
10(2/0)+** 24(2/4)+
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