29 September 1997 – Subject To Change
Internal Architecture
2–3
21164PC Microarchitecture
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Instruction translation buffer
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Branch prediction
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Instruction slotting/issue
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Interrupt support
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Integer execution unit (IEU) (Section 2.1.2)
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Floating-point execution unit (FPU) (Section 2.1.3)
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Memory address translation unit (MTU) (Section 2.1.4), which includes:
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Data translation buffer (DTB)
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Miss address file (MAF)
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Write buffer
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Dcache control
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Cache control and bus interface unit (CBU) with interface to external cache
(Section 2.1.5)
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Data cache (Dcache) (Section 2.1.6.1)
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Instruction cache (Icache) (Section 2.1.6.2)
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Serial read-only memory (SROM) interface (Section 2.1.7)
2.1.1 Instruction Fetch/Decode Unit and Branch Unit
The primary function of the instruction fetch/decode unit and branch unit (IDU) is to
manage and issue instructions to the IEU, MTU, and FEU. It also manages the
instruction cache. The IDU contains:
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Prefetcher and instruction buffer
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Instruction slot and issue logic
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Program counter (PC) and branch prediction logic
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48-entry instruction translation buffers (ITBs)
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Abort logic
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Register conflict logic
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Interrupt and exception logic