System Cache



The system cache is responsible for a great deal of the system 
performance improvement of today's PCs. The cache is a buffer 
of sorts between the very fast processor and the relatively 
slow memory that serves it. (The memory is not really slow, 
it's just that the processor is much faster.) The presence of 
the cache allows the processor to do its work while waiting for 
memory far less often than it otherwise would. 

There are in fact several different "layers" of cache in a 
modern PC, each acting as a buffer for recently-used information 
to improve performance, but when "the cache" is mentioned 
without qualifiers, it normally refers to the "secondary" or 
"level 2" cache that is placed between the processor and system 
RAM. The various levels of cache are discussed here, in the 
discussion on the theory and operation behind cache (since many 
of the principles are the same). However, most of the focus of 
this section is on the level 2 system cache.