Q. Write Policy of cache memory?
If contents of a block in cache are changed then it's essential to write it back to main memory before replacing it. Write policy determines when altered words of a block are written back to main memory. At one extreme an updated word of a block is written to main memory as soon as such updates take place in block. At other extreme all updated words of block are written to main memory only when block is replaced from cache. Latter policy minimises overheads of memory write operations however temporarily leaves main memory in an inconsistent (obsolete) state.