Cache system and cache memory control device controlling cache memory having two access modes
First Claim
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1. A cache system, comprising:
- a cache memory performing an operation to output stored data as accessed, during a first time period in a first access mode, and during a second time period that is longer than the first time period in a second access mode;
a processor performing pipeline processing of the data within said cache memory; and
an access mode control portion outputting to said cache memory one of a first access mode signal designating to operate in said first access mode and a second access mode signal designating to operate in said second access mode, based on presence/absence of pipeline stall in respective one of said access modes.
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Abstract
A branch/prefetch judgement portion, in receipt of a branch request signal, sets a cache access mode switch signal to an “H” level. Thus, a cache memory operates in the 1-cycle access mode consuming a large amount of power. In receipt of a prefetch request signal, the branch/prefetch judgement portion sets the cache access mode switch signal to an “L” level. Thus, the cache memory operates in the 2-cycle access mode consuming less power.
42 Citations
8 Claims
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1. A cache system, comprising:
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a cache memory performing an operation to output stored data as accessed, during a first time period in a first access mode, and during a second time period that is longer than the first time period in a second access mode;
a processor performing pipeline processing of the data within said cache memory; and
an access mode control portion outputting to said cache memory one of a first access mode signal designating to operate in said first access mode and a second access mode signal designating to operate in said second access mode, based on presence/absence of pipeline stall in respective one of said access modes. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A cache memory control device controlling a cache memory performing an operation to output stored data as accessed during a first time period in a first access mode and during a second time period that is longer than the first time period in a second access mode, comprising:
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a judgement portion determining whether a processor, processing data within said cache memory by selecting and operating at one of a plurality of clock frequencies, is operating at a clock frequency of not lower than a prescribed value or operating at a clock frequency of less than said prescribed value; and
an access mode control portion outputting a first access mode signal designating said first access mode when said judgement portion determines that said processor is operating at the clock frequency of not lower than said prescribed value, and outputting a second access mode signal designating said second access mode when said judgement portion determines that said processor is operating at the clock frequency of less than said prescribed value. - View Dependent Claims (8)
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Specification