Freescale Semiconductor, Inc.
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ICROPROCESSOR
The PowerPC 604e microprocessor is a 32-bit implementation of the PowerPC Reduced Instruction Set
Computer (RISC) architecture. The PowerPC 604e microprocessor provides high levels of performance
for desktop, workstation, and symmetric multiprocessing computer systems. The PowerPC 604e
microprocessor is software- and bus-compatible with the PowerPC 603e鈩? PowerPC 740鈩?and
PowerPC 750鈩?microprocessor families.
Freescale Semiconductor, Inc...
Superscalar Microprocessor
The PowerPC 604e microprocessor is a superscalar design capable of issuing four instructions per clock
cycle to seven independent execution units, including:
s
s
s
Two single-cycle integer units
One multiple-cycle integer unit
Branch processing unit
s
s
s
Load/Store unit
Floating-point unit
Condition register unit
Instructions can execute out of order and execution results can be made immediately available to
subsequent instructions through the use of rename registers. However, the completion unit retires
(commits results to architectured registers such as FPRs and GPRs) as many as four instructions per
clock cycle in order, ensuring a precise exception model.
PowerPC 604e Microprocessor
The PowerPC 604e microprocessor uses dynamic
Block Diagram
branch prediction to improve the accuracy of
instruction prefetching. This and the ability to
speculatively execute through two unresolved
branches minimize pipeline stalls.
Completion
Unit
Branch
Processing
Unit
Condition
Register
Unit
Fetch
Unit
Cache and MMU Support
The PowerPC 604e microprocessor has separate
32-Kbyte, physically-addressed instruction and data
caches. Both caches are four-way set associative and
provide byte-level parity checking.
The PowerPC 604e microprocessor also has separate
memory management units (MMUs) for instructions
and data. The MMUs support up to 4 Petabytes (2
52
)
of virtual memory and 4 Gigabytes (2
32
) of physical
memory. Access privileges and memory protection are
controlled on block and page granularities.
Dispatch
Unit
Integer Units
32 GPRs
GP Rename Reg.
Load/
Store
Unit
Floating Point Unit
32 FPRs
FP Rename Reg.
D MMU
Data Cache
I MMU
Inst. Cache
Bus Interface Unit
32b
Address
System Bus
64b
Data
Continued on back.
For More Information On This Product,
Go to: www.freescale.com
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