MC68340AB16E Datasheet, PDF (232/441 Pages) Motorola, Inc – Integrated Processor with DMA User’s Manual

Freescale Semiconductor, Inc.
12 34 56 7 8 90 12 3 4 5 6 78
CLOCK
BUS
CONTROLLER
INSTRUCTION
CONTROLLER
EXECUTION
TIME
WRITE
FOR 1
1 PRE-
FETCH
READ
FOR 2
MOVE A1,(AO)+
EA FETCH
ADDQ
WRITE
FOR 2
ADDQ
TO <EA>
MOVE.W A1,(AO)+
ADDQ.W #1,(AO)
2 PRE-
FETCH
3 PRE-
FETCH
EA CALC
CLR
3 PRE-
FETCH
CLR
<EA>
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
CMP.L
BLE.B
MOVE.L
#7, D1
D1, D0
NEXT
D1, (A0)
12 34 56 7 8 90 12 3 4
CLOCK
BUS 1 PRE-
CONTROLLER FETCH
INSTRUCTION
CONTROLLER
MOVEQ
EXECUTION MOVEQ
TIME #7,D1
2 PRE-
FETCH
CMP
CMP
D1,D0
OFFSET
CALC
PRE-
FETCH
TAKEN
PRE-
FETCH
PRE-
FETCH
TAKEN TAKEN
BLE.B NOT TAKEN
NEXT
INST.
Figure 5-34. Example 2—Branch Taken
WRITE
FOR 3
MOTOROLA
MC68340 USER’S MANUAL
5-95
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