M E M O R Y

A PC's main memory is a fast primary storage device that is directly accessible by the CPU, and is used to store the currently executing program and immediately needed data. PCs use semiconductor random access memory (RAM) of various kinds such as DRAM, SDRAM or SRAM as their primary storage. Which exact kind is used depends on cost/performance issues at any particular time. Main memory is much faster than mass storage devices like hard disk drives or optical discs, but is usually volatile, meaning that it does not retain its contents (instructions or data) in the absence of power, and is much more expensive for a given capacity than is most mass storage. As a result, main memory is generally not suitable for long-term or archival data storage.