Random access memory – called RAM, this is where data and programs are transferred to (from secondary storage) when the CPU requires them. It is volatile in that the contents of RAM are only available when the computer is on. When required, the CPU transfers data or programs from secondary storage to RAM. It does this because the CPU can access data thousands of times faster from RAM than from secondary storage. An extremely fast type of RAM, called cache (pronounced kay-**bleep**) is often found on modem computer systems. This is a section of computer memory that can be accessed at very high speeds and in which information is stored for fast retrieval. A cache size of 256Kb is common. Cache is a very expensive form of RAM, and consequently, only small amounts are used in computer systems.
