RAM

Static ram (SRAM)
This ram will maintain its data as long as power is provided to the memory chips. It does not need to be re-written periodically. In fact, the only time the data on the memory is refreshed or changed is when an actual write command is executed. SRAM is very fast, but is much more expensive than DRAM. SRAM is often used as cache memory due to its speed. There are few types of SRAM:
.Async (SRAM)
An older types of SRAM used in many pcs fofr L2 cache. It is asynchronomous, meaning that it works independently of the system clock. This means that the cpu found itself waiting for info from the L2 cache.
.SYNC SRAM
This types of ram is synchronomous, meaning its synchronized with the system clock. While this speeds it up, it makes it rahther expensive at thee same time.
.Pipeline burst SRAM
Commonly used. SRAM requests are pipelined, meaning larger packets of data re sent to the memory et once, and acted on very quickly.this breed of SRAM can operate at bus speeds higher than 66mhz, so is often used.