MOTOROLA
Chapter 10. Instruction Execution Timing
10-3
Part II. PowerPC Microprocessor Module
10.1.3 Private Writeback Bus Load
In Figure 10-4, lwz and xor write back in the same clock since they use the writeback bus
in two different ticks (a tick = 1/4 of a processor clock).
lwz r12,64
(SP)
sub
r5,r5,3
cror
4,14,1
and
r3,r4.r5
xor
r4,r3,r5
ori
r6,r12.r3
Figure 10-4. Private Writeback Bus Load Timing
10.1.4 Fastest External Load (Data Cache Miss)
Figure 10-5 shows a sub instruction dependent on the value read by the load. It causes three
bubbles in the execution stream. Assuming SCCR[EBDF] = 00, the external clock
(CLKOUT) is shifted 90
°
from the internal clock (GCLK1).
lwz
r12,64 (SP)
sub
r3,r12,3
addic
r4,r14,1
Figure 10-5. External Load Timing
ori
xor
load
lwz
sub
and
xor
cror
ori
sub
and
cror
ori
load
sub
lwz
lwz
lwz
lwz
sub
lwz
cror
and
and
xor
xor
ori
GCLK1
E Data
Fetch
Decode
Read + Execute
Writeback
L Address Drive
L Data
Cache Address
Load Writeback
E Address
cror
lwz
sub
lwz
lwz
sub
addic
sub
sub
lwz
Bubble
lwz
lwz
lwz
lwz
lwz
lwz
GCLK1
E Data
Fetch
Decode
Read + Execute
Writeback
L Address Drive
L Data
Cache Address
Load Writeback
E Address
Bubble
Bubble
Bubble
Содержание MPC860 PowerQUICC
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Страница 78: ...I iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Страница 88: ...1 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
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Страница 226: ...8 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
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Страница 274: ...III iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
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Страница 325: ...MOTOROLA Part IV Hardware Interface IV v Part IV Hardware Interface ...
Страница 326: ...IV vi MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
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Страница 998: ...37 48 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part VI Debug and Test ...
Страница 1016: ...A 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Страница 1024: ...B 8 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Страница 1030: ...C 6 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
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