Home > Primary storage

Primary storage is used to store data that is likely to be in active use, so it is usually faster than long-term secondary storage. Today, many computers have cache memory located in between the central processing unit and primary storage in order to further increase speed.

Over the history of computing, a variety of technologies have been used for primary storage. Today, we are most familiar with random access memory (RAM) made out of many small integrated circuits. Some early computers used mercury delay lines, in which a series of acoustic pulses were sent along a tube filled with mercury. When the pulse reached the end of the tube, the circuitry detected whether the pulse represented a binary 1 or 0 and caused the oscillator at the beginning of the line to repeat the pulse. Other early computers stored RAM on high-speed magnetic drums.

Modern primary storage devices include:

• Random access memory (RAM) - includes VRAM, WRAM, NVRAMNon Volatile Random Access Memory NVRAM is a computer memory chip which will not lose its information when the power is lost. It is mostly used in computer systems to store settings which must survive a power cycle (like number of disks and memory configu
• Read-only memoryRead-only memory (ROM is used as a storage medium in computers. Because it cannot (easily) be written to, its main uses lie in the distribution of software that is very closely related to hardware, and not likely to need frequent upgrading. One common use (ROM)

Before the use of integrated circuits for memory became widespread, primary storage was implemented in many different forms:

• Williams tubeThe Williams tube or (more accurately) the Williams-Kilburn tube (after Freddie Williams and coworker Tom Kilburn) was a cathode ray tube used to store electronic data. When a dot is drawn on a cathode ray tube, the spot lasts for a time that depends on t
• Delay line memory
• Drum memory
• Core memory
• Twistor memoryTwistor is a form of computer memory, similar to core memory, formed by wrapping magnetic tape around a current-carrying wire. Although the developers, Bell Labs, had high hopes for Twistor, it was used for only a brief time in the marketplace between abo
• Bubble memoryIntel bubble memory module Bubble memory is a type of computer memory that uses a thin film of a magnetic material to hold small magnetized areas, known as bubbles which each store one bit of data. Bubble memory was a very promising technology in the 1970

See also:

• Secondary storage