Static random-access memory
Static random-access memory (SRAM) is a type of RAM that keeps data that is fed to it without having to be refreshed over and over again.
Both DRAM and SRAM store information in binary by using very small electronic components. Both are volatile (need electric current flowing to keep the negative and positively charged components stay that way).
One difference is that SRAM are also used for specific applications within the PC, where their good points outweigh their bad points compared to DRAM.
Like other semiconductor chips, SRAM chips are made by photolithography.
For SRAM, each bit is composed of between four and six transistors, forming a flip-flop to hold information. This complexity is what makes SRAM bigger and more expensive than DRAM. In DRAM each bit has only one transistor plus a capacitor acting like a miniature rechargeable battery).
Advantages
- SRAM does not need to be refreshed.
- Changing Static RAM is faster than DRAM.
Disadvantages
- SRAM is more expensive than DRAM.
- SRAMs take up more space and electricity.
Static Random-access Memory Media
A static RAM chip from a Nintendo Entertainment System clone (2K × 8 bits)
SRAM cells on the die of a STM32F103VGT6 microcontroller as seen by a scanning electron microscope. Manufactured by STMicroelectronics using a 180-nanometre process. Topology of the cells is clearly visible.
Comparison image of 180 nanometre SRAM cells on a STM32F103VGT6 microcontroller as seen by an optical microscope
A six-transistor CMOS SRAM cell. WL: word line. BL: bit line.
Four-transistor SRAM provides advantages in density at the cost of manufacturing complexity. The resistors must have small dimensions and large values.
.svg){kind=spacer}
.svg){kind=spacer}
