One of the many valve racks that would have been installed in a LEO II computer.

This is probably a Register or a store unit. It has a change label on the side dated 11/6/1959, and a number 857701A/P2.

It also has a test date of 19/5/1960 and A5 written on the label side, on the other side is another mark of ECC 91 and a tick.

Valve checking policy changed many times - the transmitter/receiver would have needed regular setting up to maximum performance in the test rack. These ECC91 valves may have needed special attention.

The rack is part of our onsite display for the National Lottery Heritage funded-project 'Swiss Rolls, Tea and the Electronic Office'.

LEO II computers were installed in many British offices, including Ford Motor Company, British Oxygen Company and the 'clerical factory' of the Ministry of Pensions at Newcastle. LEO III computers were installed in Customs & Excise, Inland Revenue, The Post Office and in Australia, South Africa and Czechoslovakia. A full list of LEO II and LEO III installations is available from the LEO Computers Society website.

This Unit Was Kindly Donated By Phil Hamilton.

Phil used the rack as a lecture tool, while travelling around universities, along with a wide range of slightly more modern boards, teaching the early history of computers.

He gave us the story of how the parts came into his possession 

’I knew two English Electric Leo field engineers very well, they were always after 'easy fixits' etc. One of them had a box with old computer parts in the back of his van. 

I asked where he was going with them and he said "to the nearest scrap pile" I asked for the bits and he said gladly, they're yours for the favours you've done us.

I told him that I would keep them personally and I remember him thanking me for saving him the run to the scrap pile, wherever that was.

That was early 1970's. It wasn't until the early 90's that I started lecturing and they at last had a use after nearly 20 years storage. I was using them until end of semester 2, 2008, so they were my props for 18 years’

Phil Hamilton

19th March, 2020.

Manufacturer: LEO Computers LTD
Date: June 1959

This exhibit has a reference ID of CH56848. Please quote this reference ID in any communication with the Centre for Computing History.

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