Author: Stan Eisenstat
Subject: Re: [Cs323] Block address Index
Date: Wednesday, 07 Oct 2020, 21:45:55
> Message Posted By: Unknown > > On B-13 of HP, the diagram divides Block address into the Tag portion and > the Index portion. Does the Index portion correspond to the line # from > the notes, which was calculated by taking the hash of the block #? If so, > what is the use of the Block offset? Yes. This is a two-way associative cache with 2^9 pairs of lines of size 64 = 2^6 bytes for a total of 64KB. The 40-bit address is split into a * 25-bit block number (= tag bits) * 9-bit set number (= index) * 6-bit offset Our description of caches would have each line storing the pair (block number, set number) as the BLOCK NUMBER or TAG BITS. But since each set of lines "knows" its set number, it only needs to store the block number and not the set number. The offset bits are required to specify which bytes of the block were accessed. --Stan-PREV INDEX NEXT