Harwell CADET

By 1953 his team had transistor circuits operating to read and write on a smaller magnetic drum from the Royal Radar Establishment.

[2][3] The resulting machine was called CADET (Transistor Electronic Digital Automatic Computer – backward).

CADET was built from a few standardized designs of circuit boards which never got mounted into the planned desktop unit, so it was left in its breadboard form.

[4][5] Cooke-Yarborough described CADET as being "probably the second fully transistorised computer in the world to put to use", second to an unnamed IBM machine.

[6] In April 1955 IBM announced the IBM 608 transistor calculator, which they claim was "the first all-solid-state computing machine commercially marketed"[7] and "the first completely transistorized computer available for commercial installation",[8] and which may have been demonstrated in October 1954, before the CADET.