Motorola MPC823e User Manual

Instruction Execution Timing
8-8 MPC823e REFERENCE MANUAL MOTOROLA
INSTRUCTION EXECUTION
8
TIMING
8.2.4 A Full History Buffer
lwz r12,64 (SP)
sub r5,r5,3
addic r4,r14,1
and r3,r4.r5
xor r4,r3,r5
ori r7,r8,1
This example demonstrates the condition of a full history buffer. In this case, the history
buffer is full from executing the sub, add, and and instructions. It takes one more bubble
from the load writeback to allow further issue. This is the time for the history buffer to retire
sub, add, and and.
Figure 8-6. Example of a Full History Buffer
XOR
XORLWZ
LWZ SUB AND XORADDIC ORI
SUB
ANDADDIC
XORLWZ SUB
LWZ
LWZ
LWZ
LWZ
LWZ
SUB
LWZ
ADDIC
AD
AND
AND
BUBBLE
GCLK1
E DATA
FETCH
DECODE
READ + EXECUTE
WRITEBACK
L ADDRESS DRIVE
L DATA
CACHE ADDRESS
LOAD WRITEBACK
E ADDRESS
BUBBLE

Motorola MPC823e Specifications

General

Brand	Motorola
Model	MPC823e
Category	Computer Hardware
Language	English