| 摘要 |
PURPOSE: An information processor is provided to improve access efficiency to a main memory by limiting access to an outside main memory in a microprocessor having a cache memory. CONSTITUTION: The information processor is provided with instruction fetch parts(410, 411) for fetching both instruction systems at the sequential side and target side of a branch instruction, cache controlling parts(54, 56) for fetching instructions from a cache memory(52) or a main memory(64) in response to a fetch request from the instruction fetch part, a memory bus access part(60) for performing access to a main memory, and instruction buffers(470, 471) for holding the fetched instructions. Moreover, the information processor is provided with branch predicting parts(430, 431) for operating the branch prediction of the branch instruction stored in the instruction buffer prior to the execution of the branch instruction. When the branch direction of the branch instruction is uncertain, the cache controlling parts(54, 56) control the memory bus access to the main memory(52) after cache miss.
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