Williams Tube - the Predecessor of Modern RAM

Invention and Development of the First Random Access Computer Memory

Oct 1, 2009

Williams Tube - the Prototype of Modern RAM , Piero71

Williams Tube, the first random access computer memory, and a predecessor of modern RAM, was invented and tested in 1947 on Manchester Small-Scale Experimental Machine.

During the Second World War scientists developed a delay line memory – the signal received from a radar pulse was stored in this delay line, and, after inversion, merged with the second signal. As a result, left were only the residual signals to contain the images of the moving objects.

Computers working with this type of a memory could store only limited amounts of data, were expensive, and very demanding in maintenance. Besides, they provided sequential access to information instead of random one which was considered to be more efficient.

Invention of the Williams Tube – the First Prototype of Modern RAM

Dr. Freddie Williams at the University of Manchester was realizing that development of a device for electronic storage of data was crucially important for the further development of electronic digital computers. Therefore, while working at Telecommunications Research Establishment, in 1946 Williams started work on designing his own, modified, type of such a tube in an attempt to use it as a computer storage device, which, finally, proved to be successful.

The creation of the Williams Tube itself was a result of William’s observing an experiment that had been conducted at Bell Labs, where they used cathode ray tubes working with radars. They developed the tube as an analog for a delay line memory.

Williams designed the ‘memory’ in such a way that it read the charge and rewrote it continuously at electronic speeds. This allowed the data to be kept permanently, and finally this sequence of actions was called ‘regeneration’. Afterwards it was implemented in contemporary RAMs to replenish charge. So, the next step was to build a computer that would be able to use the created memory.

Manchester Small-Scale Experimental Machine – The Baby

A special computer was designed to test the qualities of this memory - Manchester Small-Scale Experimental Machine, also called The Baby, being the first computer of this type.

The first function performed by the machine was determining the highest factor of a number. When, in several days, the scientists tried running it on 218, it worked for 52 minutes, and consumed around 2.1 million instructions plus 3.5 million operations. The program to perform this operation was written by Kilburn and had 17 instructions.

Still, at that time it was a revolutionary step in technology.

Williams Tube was invented by Freddie Williams at the University of Manchester, and successfully tested in 1947 on Manchester Small-Scale Experimental Machine. This machine was designed specifically for testing the first random access computer memory.

Sources:

Lavington, S. H., 1975. History of Manchester Computers. Manchester: NCC Publications.
The Computer Conservation Society, 1992. "Early computers at Manchester University" Resurrection, The Bulletin of the Computer Conservation Society 1 (4), pp. 20-26.
The University of Manchester, 1998, 1999. “The Manchester Small Scale Experimental Machine - "The Baby". Computer50.org.
Tootill, G., 1998. "The Original Original Program". Resurrection, The Bulletin of the Computer Conservation Society, 20, pp. 9-19.

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