early memories

We expect the billions of storage cells in our computer's memory to work hours on end without failing. Little do most people realize that it took a half century to develop memory technologies to where they are today. Following are some of the first internal memory technologies used in computers in the early 1950s. See memory types. See also early storage devices.

Electrostatic Memory

Similar to a CRT, electrostatic storage tubes used in the Whirlwind computer in 1950 held a whopping 256 bits each. The bits were "painted" on the surface of the tube, and their electrostatic charges determined their content. See Williams tube. (Image courtesy of The MITRE Corporation Archives.)

Delay Line Memory

In the late 1940s and early 1950s, the EDSAC and UNIVAC I memory consisted of tubes of liquid mercury several feet long. In a continuous loop, electrical pulses were converted to sound and back to electrical, keeping the digital data flowing in the tube as if it were stored there (see image below). See EDSAC and UNIVAC I.

Liquid Mercury Delay Line Memory

This was a Univac I memory module in 1951. It contained seven liquid mercury tanks, each divided into 18 channels, totaling 1,000 words that held 11 decimal digits or two instructions. The top image shows relative size. (Photo taken courtesy of The Computer History Museum, www.computerhistory.org)

Magnetic Drum Memory

This magnetic drum from an IBM 650 was introduced in 1954 and held two thousand 10-digit words. That much memory today would fit on the head of a pin, and a very thin pin to be sure (see IBM 650). (Image courtesy of the Hagley Museum and Library.)

Magnetic Core Memory

In the early 1950s, magnetic cores were introduced and widely used for two decades. The direction of the magnetic energy in the core determined the 0 or 1. This core plane, which held 256 bits, replaced the electrostatic storage tubes in the Whirlwind I. See core storage. (Image courtesy of The MITRE Corporation Archives.)

Cores Got Very Sophisticated

Over the years, magnetic cores became so small that a thousand of them would look like a tiny pile of dust. Using a microscope, women in third-world countries were hired to string them together. About 30" high, this Dataram module provided 16KB of RAM for a Data General minicomputer in 1967. See core storage.