
10-2
MPC860 PowerQUICC UserÕs Manual
MOTOROLA
Part II. PowerPC Microprocessor Module
Figure 10-1. Data Cache Load Timing
10.1.2 Writeback Arbitration
In Figure 10-2, the addic instruction is dependent on the mulli result. Because the
single-cycle instruction sub has priority on the writeback bus over the mulli, the mulli
writeback is delayed one clock and causes a bubble in the execute stream.
mulli r12,r4,3
sub r3,r15,3
addic 4,r12,1
Figure 10-2. Writeback Arbitration TimingÑExample 1
In this example, the addic instruction is dependent on sub rather than on mulli. Although
the writeback of the mulli is delayed two clocks, there is no bubble in the execution stream.
mulli r12,r4,3
sub r3,r15,3
addic r4,r3,1
Figure 10-3. Writeback Arbitration TimingÑExample 2
lwz
sub
mulli
addi
addic
Fetch
Decode
Read + Execute
Writeback
L Address Drive
L Data
Load Write Back
lwz
sub
Bubble
addic
lwz
sub
sub
addic
ld
ld
ld
GCLK1
addic
mulli
sub
addic
Fetch
Decode
Read + Execute
Writeback
mulli
sub
Bubble
addic
mulli
sub, mulli
mulli
addic
sub
GCLK1
addic
mulli
sub
addic
Fetch
Decode
Read + Execute
Writeback
mulli
sub
addic
mulli
sub, mulli
mulli
addic
sub
GCLK1
addic
Summary of Contents for MPC860 PowerQUICC
Page 3: ...MPC860UM AD 07 98 REV 1 MPC860 PowerQUICC ª UserÕs Manual ...
Page 36: ...xxxvi MPC860 PowerQUICC UserÕs Manual MOTOROLA CONTENTS Paragraph Number Title Page Number ...
Page 78: ...I iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 88: ...1 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 114: ...3 16 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 226: ...8 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
Page 262: ...9 36 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
Page 274: ...III iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Page 320: ...12 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Page 325: ...MOTOROLA Part IV Hardware Interface IV v Part IV Hardware Interface ...
Page 326: ...IV vi MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 352: ...13 26 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
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Page 426: ...15 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 530: ...17 26 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 632: ...21 44 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 660: ...22 28 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 708: ...24 24 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 748: ...27 20 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 846: ...31 20 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
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Page 948: ...36 34 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 998: ...37 48 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part VI Debug and Test ...
Page 1016: ...A 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1024: ...B 8 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1030: ...C 6 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1086: ...Glossary 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA ...
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