11. Cache Organization, Operation, and Coherency
As Figure 11-1 shows, the R4000 contains separate primary instruction and data caches. Figure 11-1 also shows that the R4000 supports a secondary cache that can be split into separate portions, one portion containing data and the other portion containing instructions, or it can be a joint cache, holding combined instructions and data.
This section describes the organization of on-chip primary caches and the optional off-chip secondary cache. Table 11-1 lists the cache and cache coherency support for the three R4000 models.
Table 11-1 R4000 Cache and Coherency Support
Figure 11-2 provides block diagrams of the three R4000 models:
- R4000PC, which supports only the primary cache
- R4000SC and R4000MC, which support both primary and secondary caches
Figure 11-2 Cache Support in the R4000PC, R4000SC, and R4000MC
Copyright 1996, MIPS Technologies, Inc. -- 21 MAR 96
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