Typewriter User Manual

MOTOROLA MC68340 USER’S MANUAL 5- 95
CLOCK
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0
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BUS
CONTROLLE
R
INSTRUCTION
CONTROLLE
R
EXECUTION
TIM
E
WRITE
FOR
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1 PRE-
F
ETC
H
READ
F
OR
2
WRITE
FOR
2
2 PRE-
F
ETC
H
ADDQ
T
O <EA
>
ADDQ.W #1,(AO)
EA FETCH
ADDQ
MOVE A1,(AO)+
MOVE.W A1,(AO)+
EA CALC
CLR
CLR
<
EA
>
3 PRE-
F
ETC
H
3 PRE-
F
ETC
H
WRITE
FOR
3
CLR.W $30(A1)
Figure 5-33. Example 1—Instruction Stream
5.7.2.2 TIMING EXAMPLE 2—BRANCH INSTRUCTIONS. Example 2 shows what
happens when a branch instruction is executed for both the taken and not-taken cases.
(see Figures 5-34 and 5-35). The instruction stream is for a simple limit check with the
variable already in a data register.
Instructions
MOVEQ #7, D1
CMP.L D1, D0
BLE.B NEXT
MOVE.L D1, (A0)
CLOCK
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INSTRUCTION
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ONTROLLE
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EXECUTION
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ETC
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CMP
D
1,D
0
2 PRE-
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ETC
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WRITE
FOR
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CMP
MOVEQ
MOVEQ
#7,D1
BLE.B NOT TAKEN
OFFSET
CALC
NEXT
INST.
PRE-
F
ETC
H
PRE-
F
ETC
H
PRE-
FETCH
TAKEN
TAKEN
TAKEN
Figure 5-34. Example 2—Branch Taken
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cale Semiconductor,
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