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)
(d16,An)
(d8,An,Xn)+
(xxx).W
(xxx).L
(d16 PC)
(d8, 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