Memory cell definition (computing)

The cell or memory cell is the fundamental component of computer memory. The memory cell is an electronic circuit that stores one bit of binary information and must be set to store a logic 1 (high voltage level) and reset to store a logic 0 (low voltage level). Its value is kept/stored until it is modified by the set/reset process. The value of the memory cell can be accessed by reading it.

Many different memory cell architectures have been used throughout computing history, including core memory and bubble memory, but the most common are flip-flops and capacitors.

The SRAM static memory cell is a type of flip-flop circuit, usually implemented using FETs. These require very little power to maintain the stored value when not being accessed.

A second type, DRAM, is based on a capacitor. The charging and discharging of this capacitor can store a «1» or a «0» in the cell. However, the charge in this capacitor will leak away slowly, and must be refreshed periodically. Due to this upgrade process, DRAM uses more power, but can achieve higher storage densities.

Memory cell description

The memory cell is the fundamental component of memory. It can be implemented using different technologies, such as bipolar, MOS, and other semiconductor devices. It can also be built from magnetic material such as ferrite cores or magnetic bubbles.

Regardless of the implementation technology used, the purpose of the binary memory cell is always the same. It stores a bit of binary information that can be accessed by reading the cell and must be set to store a 1 and reset to store a 0.

Brief history

On December 11, 1946, Freddie Williams applied for a patent on his cathode ray tube (CRT) storage device (Williams tube) with 128 40-bit words. In that year, Frederick Viehe filed the first patent applications for magnetic core memory. An Wang, Ken Olsen, and Jay Forrester also contributed to its development.

The first modern memory cells were introduced in 1965, when John Schmidt designed the first 64-bit p-channel SRAM.

The first 64-bit bipolar SRAM was released by Intel in 1969 with the 3101 Schottky TTL. A year later, it launched the first DRAM chip, the Intel 1103, which in 1972 broke all world records for semiconductor memory sales.