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MPC7447A RISC Microprocessor Hardware Specifications, Rev. 5

Freescale Semiconductor 3

Features

NOTE

The MPC7447A is a footprint-compatible, drop-in replacement in an

MPC7447 application if the core power supply is 1.3 V.

2Features

This section summarizes features of the MPC7447A implementation of the PowerPC architecture.

Major features of the MPC7447A are as follows:

• High-performance, superscalar microprocessor

— Up to four instructions can be fetched from the instruction cache at a time.

— Up to 12 instructions can be in the instruction queue (IQ).

— Up to 16 instructions can be at some stage of execution simultaneously.

— Single-cycle execution for most instructions

— One instruction per clock cycle throughput for most instructions

— Seven-stage pipeline control

• Eleven independent execution units and three register files

— Branch processing unit (BPU) features static and dynamic branch prediction

– 128-entry (32-set, four-way set-associative) branch target instruction cache (BTIC), a cache

of branch instructions that have been encountered in branch/loop code sequences. If a target

instruction is in the BTIC, it is fetched into the instruction queue a cycle sooner than it can

be made available from the instruction cache. Typically, a fetch that hits the BTIC provides

the first four instructions in the target stream.

– 2048-entry branch history table (BHT) with 2 bits per entry for four levels of

prediction—not taken, strongly not taken, taken, and strongly taken

– Up to three outstanding speculative branches

– Branch instructions that do not update the count register (CTR) or link register (LR) are

often removed from the instruction stream.

– Eight-entry link register stack to predict the target address of Branch Conditional to Link

— Four integer units (IUs) that share 32 GPRs for integer operands

– Three identical IUs (IU1a, IU1b, and IU1c) can execute all integer instructions except

multiply, divide, and move to/from special-purpose register instructions.

– IU2 executes miscellaneous instructions including the CR logical operations, integer

multiplication and division instructions, and move to/from special-purpose register

instructions.

— Five-stage FPU and a 32-entry FPR file

– Fully IEEE 754-1985–compliant FPU for both single- and double-precision operations

– Supports non-IEEE mode for time-critical operations

– Hardware support for denormalized numbers

– Thirty-two 64-bit FPRs for single- or double-precision operands

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