Cache

Ref: Tanenbaum A. Structured Computer Organization

Ref: Capron HL Computere - Tools for an Information Age (5th ed) Chapter 3

Cache memory is a high speed memory which is in addition to the main memory of the computer. Cache hold tha instruction and data of a computer program that is most heavily used.

Cache works as follows:

Copies of the most often used "blocks" of data are copied to cache memory. When a program requires the data, it checks first to see if it is in cache. If it is, that data is used. If not, it is fetched from main memory. Data fetched from cache memory is much more quickly accessed which leads to faster operation of the computer.

Most modern microcomputers have two levels of cache. The first is on the processor itself which provides a very high speed cache system as the data is right in the processor itself. The second is on the motherboard which is made of very special, high speed RAM which provides data much faster than standard Random Access Memory (RAM). This memory is usually no more than 512k.

Author: Mike Leishman