| 摘要 |
In a pipelined microprocessor which includes a prefetch unit for obtaining a plurality of instructions to be processed; a decode unit having a prefix state machine for decoding prefixes and determining their lengths, a decode circuit for decoding instructions and generating microcode vectors to be executed, and apparatus for counting the length of an instruction; and a microcontroller for sequencing microcode vectors; the improvement including apparatus for detecting the appearance of a particular prefixed instruction, apparatus responsive to the detection of the particular prefixed instruction for disabling the prefix state machine, apparatus in the decode circuit for decoding the particular prefixed instruction and causing the decode circuit to generate microcode vectors for the instruction, and apparatus for generating a request to the microcontroller to handle microcode vectors generated.
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