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Static random-access memory (static RAM or SRAM) is a type of random-access memory (RAM) that uses latching circuitry (flip-flop) to store each bit. SRAM is volatile memory; data is lost when power is removed. The static qualifier differentiates SRAM from dynamic random-access memory (DRAM):
In SRAM, the memory cell is a type of flip-flop circuit, usually implemented using FETs. This means that SRAM requires very low power when not being accessed, but it is expensive and has low storage density. A second type, DRAM, is based around a capacitor. Charging and discharging this capacitor can store a "1" or a "0" in the cell.
Common flash devices such as USB flash drives and memory cards provide only a block-level interface, or flash translation layer (FTL), which writes to a different cell each time to wear-level the device. This prevents incremental writing within a block; however, it does help the device from being prematurely worn out by intensive write patterns.
Flash memory – In this type the writing process is intermediate in speed between EEPROMS and RAM memory; it can be written to, but not fast enough to serve as main memory. It is often used as a semiconductor version of a hard disk , to store files.
Flash memory is produced using semiconductor linewidths of 30 nm at Samsung (2007) while FeRAMs are produced in linewidths of 350 nm at Fujitsu and 130 nm at Texas Instruments (2007). Flash memory cells can store multiple bits per cell (currently 4 in the highest density NAND flash devices), and the number of bits per flash cell is projected to ...
The only current memory technology that easily competes with MRAM in terms of performance at comparable density is static random-access memory (SRAM). SRAM consists of a series of transistors arranged in a flip-flop, which will hold one of two states as long as power is applied. Since the transistors have a very low power requirement, their ...
The AVRs have 32 single-byte registers and are classified as 8-bit RISC devices. Flash, EEPROM, and SRAM are all integrated onto a single chip, removing the need for external memory in most applications. Some devices have a parallel external bus option to allow adding additional data memory or memory-mapped devices.
CMOS memory was commercialized by RCA, which launched a 288-bit CMOS SRAM memory chip in 1968. [23] CMOS memory was initially slower than NMOS memory, which was more widely used by computers in the 1970s. [24] In 1978, Hitachi introduced the twin-well CMOS process, with its HM6147 (4 kb SRAM) memory chip, manufactured with a 3 μm process. The ...