SRAM stands for Static Random Access Memory and is a type of semiconductor memory that uses bistable latching circuitry (flip-flop) to store each bit. It holds data bits in its memory so long as power is being supplied. It cannot hold data if power is removed. SRAM is used where speed or low power are needed. It’s higher density than DRAM, and less complicated structure makes it ideal to use in semiconductor memory scenarios where high capacity memory is used as seen in the working memory within computers.
SRAM is different to DRAM (dynamic RAM, which stores bits in cells consisting of a capacitor and a transistor), due to the fact that SRAM does not have to be refreshed unlike Dynamic which will lose data unless refreshed periodically. Also SRAM is faster and more expensive than DRAM.
SRAM is used for a computer’s cache memory as well as being part of the RAM digital to analogue converter found on a video card. SRAM can be designed with a general CMOS technology process with six transistors (6T memory cell) and no capacitors. Since transistors do not require power to prevent leakage, SRAM does not have to be refreshed on a regular basis:
- Data is held statically – data is held in the semiconductor memory, no need to refresh data after every read data operation as long as the power is applied to the memory
- Three operational states which are hold, write and read
- Bistable (cross-coupled) INVs for storage
- Access transistors MAL and MAR – access to stored data for read and write
- Word line, WL, controls access – WL=0 (hold operation), WL=1 (read/write operation)
- Long data lifetime
- LCD screens and printers