SEMICONDUCTOR MEMORY DEVICES 447
size of the cache, better is the performance – but only up to a limit – beyond that, the additional
complexity that comes along with it, tends to defeat the advantage obtained.
However, more important than all these is to decide and fi nalize the ‘organization’ of the
cache. An important point to note and remember at all times is that a cache stores only a ‘copy’
of a portion of the content of main memory. Compared to the size of the main memory, the
cache is many times smaller. So, at any time, the ‘large main memory’ maps into a ‘small cache’.
ere are many mapping techniques for this and this constitutes the organization of the cache.
Let us start in the following way. e main memory is divided into blocks ...