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Snoopy Bus Protocols
Cache Protocols
Cache = fast buffer memory.
Holds recently accessed data.
Organized in lines of
n
memory words.
e.g. 8192 lines
*
4 words
*
4 bytes.
Read access:
Cache hit: word is read from cache.
Cache miss: bus transfer takes place.
Cache line read from memory.
Replaces some (e.g. least recently used) line.
Write access:
Problem: problem cache consistency.
Processor modifies content of cache line.
Other processors hold invalid copies.
Author:
Wolfgang Schreiner
Last Modification: December 23, 1997