Williams Tube - Development

Development

Developed at the University of Manchester in England, it provided the medium on which the first electronically stored-memory program was implemented in the Manchester Small-Scale Experimental Machine (SSEM) computer, which first successfully ran a program on 21 June 1948. In fact, rather than the Williams tube memory being designed for the SSEM, the SSEM was a testbed to demonstrate the reliability of the memory. Tom Kilburn wrote a 17-line program to calculate the highest factor of 218. Tradition at the university has it that this was the only program Kilburn ever wrote.

The Williams tube tended to become unreliable with age, and most working installations had to be "tuned" by hand. By contrast, mercury delay line memory was slower and not truly random access, as the bits were presented serially, which complicated programming. Delay lines also needed hand tuning, but did not age as badly and enjoyed some success in early digital electronic computing despite its data rate, weight, cost, thermal and toxicity problems. However, the Manchester Mark 1, which used Williams tubes, was successfully commercialised as the Ferranti Mark 1. Some early computers in the USA also used the Williams tube, including the IAS machine (originally designed for Selectron tube memory), the UNIVAC 1103, Whirlwind, IBM 701, IBM 702 and the Standards Western Automatic Computer (SWAC). Williams tubes were also used in the Soviet Strela-1, in the Japan TAC (Tokyo Automatic Computer).