Imperial College Computing Engines

The first Imperial College Computing Engine, ICCE I , was constructed by Sidney Michaelson, Tony Brooker and Keith Tocher in the Department of Mathematics at Imperial College in the late 1940's and early 1950's. It was a relay based machine which gave relatively slow but highly reliable service. Its current whereabouts is unknown.

These ICCE I Festive cards show parts of a tabulation of the square roots of integers.

The following photograph of the ICCE I arithmetic unit is from around 1949. Tony Brooker, its constructor, comments:

As I recall it had 20 digits (or 19 + sign) and each digital stage was made up (I think) from 5 Siemens high speed relays (1 ms) each with a single change over contact. All the other relays were PO type which carried up to 6 change over contacts and were therefore much slower (20ms?). The two types can be seen in the coverless racks (6 - 10 counting down from the top). They are all high speed except for those in col 4 (from the left).

The following photo shows a front view of ICCE I.

For Prof Brooker's Introduction to Tocher's ICCE report see here

For more details of ICCE I, see:

K. D. Tocher, `Report of the work of the Computer Group. Part 1', Mathematics Department, Imperial College, October 1952 here

S. Michaelson, `The Imperial College Computing Engine', in K. Boden (Ed), `Faster than Thought', pp 161-164, Pitman, 1953

ICCE II was constructed by Sidney Michaelson, Keith Tocher and Manny Lehman in the the early 1950's. This valve based machine was never completed. ICCE II was taken by Keith Tocher to British Steel. Its current whereabouts is unknown.

The following photographs of ICCE II are from around 1953.

1. Inside ICCE II. 2. Outside ICCE II. 3. Details of arithmetic unit wiring. 4. The power supply.
5. The power supply. 6. The pulse generator. 7. The console. 8. A flip-flop unit.
9. A rack of flip-flops. 10. A general view of ICCE II. 11. The input/output. 12. The arithmetic unit backplane.

For a PowerPoint presentation on "ICCEs I, II and SABRAC" by Prof Manny Lehman of Imperial College, see here

For more details of ICCE I and II, and the politics surrounding their construction, see:

`Computing', in A. Whitworth (Ed), `A Centenary History: A history of the City and Guild's College, 1885 to 1985', Imperial College, 1985

Many thanks to Prof Tony Brooker for the machine readable report on ICCE I, the ICCE I AU photo and his comments.

Many thanks to David Tocher for the second photo of ICCE I and the first two photos of ICCE II.

Many thanks to Prof Manny Lehman of Imperial College for his help in identifying the ICCE photographs.