AN2797 Freescale Semiconductor / Motorola, AN2797 Datasheet - Page 2

• Manufacturer Part Number: AN2797
• Description: Migrating from IBM 750GX to MPC7447A
• Manufacturer: Freescale Semiconductor / Motorola

Feature Overview
2
There are many differences between the IBM 750GX and MPC7447A devices beyond the clear differences of the
core complex. This chapter covers the differences between the cores and then other areas of interest including the
cache configuration and system interfaces.
2.1
The key processing elements of the G3 core complex used in the 750GX are shown in
complex used in the 7447A in
2
Completion Unit
Reorder Buffer
(6 Entry)
Reservation Station
Additional Features
• Time Base Counter/Decrementer
• Clock Multiplier
• JTAG/COP Interface
• Thermal/Power Management
• Performance Monitor
Feature Overview
Integer Unit 1
Cores
+ x ÷
32-Bit
2 Instructions
Reservation Station
Integer Unit 2
+
Figure
(Original)
Reservation Station
DTLB
System Register
SRs
Migrating from IBM 750GX to MPC7447A, Rev. 1.0
Data MMU
Unit
2.
Figure 1. IBM 750GX Core Complex
Instruction Queue
Fetcher
DBAT
Array
(6 Word)
CR
32-Bit
Dispatch Unit
Rename Buffers
GPR File
Instruction Unit
PA
(6)
Tags
EA
32-Bit Address Bus
Branch Processing
64 Entry
64-Bit
(2 Instructions)
32-Bit
32-Kbyte
BTIC
D Cache
BHT
64-Bit Data Bus
64-Bit
Unit
Reservation Station
Load/Store Unit
(EA Calculation)
Store Queue
(2 Entry)
CTR
LR
+
60x Bus Interface Unit
Instruction Fetch Queue
L1 Castout Queue
Data Load Queue
17-Bit L2 Address Bus
64-Bit L2 Data Bus
64-Bit
Rename Buffers
(Shadow)
FPR File
Instruction MMU
ITLB
SRs
(6)
Figure 1
64-Bit
Array
IBAT
64-Bit
Freescale Semiconductor
Reservation Station
and the G4 core
Floating-Point
L2 Controller
FPSCR
FPSCR
L2 Tags
+ x ÷
L2CR
Unit
(4 Instructions)
Tags
128-Bit
32-Kbyte
I Cache