Central Processing Unit
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
3-3
3.2
RCPU Key Features
Major features of the RCPU include:
•
High-performance microprocessor
— Single clock-cycle execution for many instructions
•
Five independent execution units and two register files
— Independent LSU for load and store operations
— BPU featuring static branch prediction
— A 32-bit integer unit (IU)
— Fully IEEE 754-compliant FPU for both single- and double-precision operations except as
noted in
Section 3.4.4, “Floating-Point Unit (FPU)
,” or refer to the
RCPU Reference Manual.
— 32 general-purpose registers (GPRs) for integer operands
— 32 floating-point registers (FPRs) for single- or double-precision operands
•
Facilities for enhanced system performance
— Atomic memory references
•
In-system testability and debugging features
•
High instruction and data throughput
— Condition register (CR) look-ahead operations performed by BPU
— Branch-folding capability during execution (zero-cycle branch execution time)
— Programmable static branch prediction on unresolved conditional branches
— A pre-fetch queue that can hold up to four instructions, providing look-ahead capability
— Interlocked pipelines with feed-forwarding that control data dependencies in hardware
•
Class code compression model support
— Efficient use of internal Flash (MPC564) and external Flash (MPC562/MPC564) by increasing
code density up to 100%
3.3
Instruction Sequencer
The instruction sequencer provides centralized control over data flow between execution units and register
files. It implements the basic instruction pipeline, fetches instructions from the memory system, issues
them to available execution units, and maintains a state history that is used to back up the machine in the
event of an exception.
The instruction sequencer fetches instructions from the burst buffer controller into the instruction pre-fetch
queue. The BPU extracts branch instructions from the pre-fetch queue and, using branch prediction on
unresolved conditional branches, allows the instruction sequencer to fetch instructions from a predicted
target stream while a conditional branch is evaluated. The BPU folds out branch instructions for
unconditional or conditional branches unaffected by instructions in the execution stage.
Instructions issued beyond a predicted branch do not complete execution until the branch is resolved,
preserving the programming model of sequential execution. If branch prediction is incorrect, the
instruction unit flushes all predicted path instructions, and instructions are issued from the correct path.
Summary of Contents for MPC561
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Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...