Motorola MPC823e User Manual

Instruction Execution Timing
8-6 MPC823e REFERENCE MANUAL MOTOROLA
INSTRUCTION EXECUTION
8
TIMING
In this example, the addic instruction is dependent on the sub rather than on the mulli .
Although the writeback of the mulli is delayed two clocks, there is no bubble in the execution
stream.
8.2.2.2 PRIVATE WRITEBACK BUS LOAD
lwz r12,64 (SP)
sub r5,r5,3
cror 4,14,1
and r3,r4.r5
xor r4,r3,r5
or r6,r12.r3
The load and the xor writeback in the same clock since they use the writeback bus in two
different ticks.
Figure 8-4. Example of a Private Writeback Bus Load
ORI
XORLOAD
LWZ SUB AND XORCROR ORI
SUB
ANDCROR
ORILOAD SUB
LWZ
LWZ
LWZ
LWZ
LWZ
SUB
LWZ
CROR
CR
AND
AND
XOR
XOR
ORI
GCLK1
E DATA
FETCH
DECODE
READ + EXECUTE
WRITEBACK
L ADDRESS DRIVE
L DATA
CACHE ADDRESS
LOAD WRITEBACK
E ADDRESS

Motorola MPC823e Specifications

General

Brand	Motorola
Model	MPC823e
Category	Computer Hardware
Language	English