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)
12(2/0)
20(4/0)
BRA
Byte
Word
18(4/0)
—
BSR
Byte
Word
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.
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