MOTOROLA
MC68000 8-/16-/32-MICROPROCESSORS USER’S 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)
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