The National-Elliott 405 was a valve-powered 32-bit computer introduced in 1956. The UK’s GPO – the then-nationalised post office and telecommunications organisation – used two of them for its London Electronic Agency for Pay and Statistics (LEAPS).
The manager of the computer centre, SD ‘Big Doug’ Selway, kept a number of documents relating to his time there, and that’s what you can find here.
For more explanation and a general introduction, read this post.
- National-Elliott 405 Basic Information (pocket-size cheat sheet).
- A simplified representation of the National-Elliott Electronic Data Processing System (six-page brochure).
- Elliott Brothers (computer company), Wikipedia.
- Systems Architecture for Elliott 401, 402, 403 & 405 computers (PDF).
- Installing of a National 405 computer at Dansom Lane. A film (no audio) documenting the installation of a National-Elliott 405 . Yorkshire Film Archive/North East Film Archive.
- Tomorrow’s World: Nellie the School Computer. Forrest Grammar School in Winnersh was donated a 405, which the schoolboys got to operate – for a while. It was scrapped in 1971 with only one delay line surviving (see link below). You can see a faulty delay line being swapped out in the film. BBC, 15 February 1969. Via YouTube.
- Elliott 405 Nickel Delay Line from “Nellie”.
- A 405 at the Museum of Applied Arts & Sciences, NSW, Australia. MAAS.
- Framboise 314. A drole comparison between the Elliott 405 and a Raspberry Pi. It’s in French, but if you don’t read the language you can always enjoy the pictures.