-Cache Operation Modes

11.8 Cache Coherency Overview

Cache Operation Modes

The R4000 processor supports the following two cache modes:

secondary-cache mode (R4000MC and R4000SC models; for R4000MC all five cache coherency attributes described above are applicable, and for R4000SC only uncached and noncoherent coherency attributes are applicable)
no-secondary-cache mode (only uncached and noncoherent coherency attributes are applicable).

Secondary-Cache Mode

In its secondary-cache mode, an R4000MC model provides a set of cache states and mechanisms that implement a variety of cache coherency protocols. In particular, the processor simultaneously supports both the write-invalidate and write-update protocols.

No-Secondary-Cache Mode

A processor in no-secondary-cache mode supports the uncached and noncoherent coherency attributes. These two attributes are described in the section titled Cache Coherency Attributes in this chapter.

Copyright 1996, MIPS Technologies, Inc. -- 21 MAR 96

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