Harwell CADET
| Manufacturer | AERE |
|---|---|
| Release date | February 1955 |
| Memory | 64k |
| Predecessor | Harwell Dekatron Computer |
The Harwell CADET was the first fully transistorised computer in Europe, and the second fully transistorised computer.
The electronics division of the Atomic Energy Research Establishment at Harwell, UK built the Harwell Dekatron Computer in 1951[1], which was an automatic calculator where the decimal arithmetic and memory were electronic, although other functions were performed by relays. By 1953 it was evident that this did not meet AERE's computing needs, and AERE director Sir John Cockcroft encouraged them to design and build a computer using transistors throughout.
E.H. Cooke-Yarborough based the design around a 64 kilobyte magnetic drum memory store with multiple moving heads that had been designed at the National Physical Laboratory, UK. By 1953 his team had transistor circuits operating to read and write on a smaller magnetic drum from the Royal Radar Establishment. The machine used a low clock speed of only 58kHz to avoid having to use any valves to generate the clock waveforms. This slow speed was partially offset by the ability to add together eight numbers concurrently[2][3].
The resulting machine was called CADET (Transistor Electronic Digital Automatic Computer - backwards). It first ran a simple test program in February 1955. CADET used 324 point-contact transistors provided by the UK company Standard Telephones and Cables which were the only ones available in sufficient quantity when the project started. Although 76 junction transistors were used for the first stage amplifiers for data read from the drum, since point-contact transistors were too noisy. CADET was built from a few standardised designs of circuit boards which never got mounted into the planned desktop unit, so it was left in its breadboard form. From August 1956 CADET was offering a regular computing service, during which it often executed continuous computing runs of 80 hours or more[4][5].
Cooke-Yarborough described CADET as being "probably the second fully transistorised computer in the world to put to use"[6]. The Manchester University Transistor Computer demonstrated a working prototype in 1953 which incorporated transistors before CADET was operational, although that required some tubes given its faster speed, so it was not the first fully transistorised computer. In the USA, the Bell Laboratories TRADIC was fully transistorised and was completed in January 1954[7] before CADET. Also in the USA, the TX-0 at MIT went on-line in 1956, while in Austria, the Mailüfterl was built in 1955, but did not run until after February.
By 1956 Brian Flowers, head of the theoretical physics division at AERE, was convinced that the CADET provided insufficient computing power for the needs of his numerical analysts and ordered a Ferranti Mercury computer. In 1958 Mercury number 4 became operational at AERE to accompany the CADET for another two years before the CADET was retired after four years operation.
See also
References
- ^ Howlett, Jack. "Computing at Harwell". Retrieved 2008-12-07.
- ^ Cooke-Yarborough, E.H. (1957). Introduction to Transistor Circuits. Edinburgh: Oliver and Boyd. p. 139.
- ^ Cooke-Yarborough, E.H. (June 1998). "Some early transistor applications in the UK". Engineering and Science Education Journal. 7 (3). London, UK: IEE: 100–106. ISSN 0963-7346. Retrieved 2009-06-07.
- ^
Lavington, Simon (1980). Early British Computers. Manchester University Press. p. 139. ISBN 0-7190-0803-4.
{{cite book}}: Check|authorlink=value (help); External link in|authorlink= - ^ Cooke-Yarborough, E.H. (1956). "transistor digital computer". Proceedings of the IEE. 103B (Supp 1-3). London, UK: IEE: 364–70. ISSN 0956-3776.
{{cite journal}}: Cite has empty unknown parameter:|coauthors=(help) - ^ Cooke-Yarborough, E.H. (June 1998). "Some early transistor applications in the UK". Engineering and Science Education Journal. 7 (3). London, UK: IEE: 100–106. ISSN 0963-7346. Retrieved 2009-06-07.
- ^ Irvine, M. M. (July-Sept. 2001). [doi:10.1109/85.948904 "Early Digital Computers at Bell Telephone Laboratories"]. IEEE Annals of the History of Computing. 23 (3). London, UK: IEEE: 22–42. Retrieved 2009-06-07.
{{cite journal}}: Check|url=value (help); Check date values in:|date=(help)