Photographs showing the development of the LEO 1 computer, 1949-1954.
1. Shows part of a room on second floor of WX block, Cadby Hall where LEO I was built. On left first 2 racks made by Lyons Engineering W/S with units made by Wayne Kerr Laboratories.
2. Part of one of 2 rooms over gateway to St Mary's College, part of Cadby Hall, where original experiments leading to LEO I designs were performed. 1949
3. Also in St Mary's College experimental delay tube on the bench. 1949
4. Feb 1950 - 2 racks
5. Ernest Lenaerts at blackboard; Ray Shaw and Ernest Kaye getting ready on 8 Feb 1950 for a demonstration to Lyons Directors on 8 March 1950
6. JMM Pinkerton explains the demonstration which showed storage and binary addition. The complete system was still some way off. 8 March 1950
7. Close up of a rack. Open wiring between units. All leads were terminated, though not accurately. (Feb 1950)
8. Gordon Gibbs, and Ray Shaw look at a circuit diagram. (Feb 1950)
9. Part of Leo I computer at Cadby Hall, London, W14.
10. Group photograph 1950. G R Gibbs, Jean Cox, W H Dutton, R T Shaw, E J Kaye, J M M Pinkerton, E H Lenaerts, B Plant, David Wheeler.
11. The set up for the demo of 8 March 1950
12. Pulses on an oscilloscope showing accumulator contents 8 March 1950
13. Some of the racks involved in the demo. They represented the main parts of the arithmetic unit. Short one word delay tubes mounted on the racks.
14. More racks in position with the exhaust trunking to remove the considerable heat developed by the valves. 20 June 1950.
15, 16 17. Work in progress in WX block. Computer &Co-ordinator Racks (2) and power supplies (1).
18. A Storage unit for recycling pulses with 1 word delay line. 20 June 1950
19. A test rack for testing and powering up newly made units. 20 June 1950
20 . Delay line pieces with a box to produce single pulses. 20 June 1950
21. Ray Shaw looks at some delay line parts.
22. One of the five batteries of 16 delay lines in its "coffin" - a thermally lagged enclosure. A box containing the electrical matching sections is also shown.
23. JMM Pinkerton (poss Ernest Lenaerts) looking at a teleprinter adapted for five wire operations.
24. The LEO I control console partly fitted up.
25. Another view of a storage unit and short delay line.
26. Demonstration 8 March 1950
27. A general view of LEO I down the centre aisle. There were 4 rows of 4 racks with spaces for 12 units in each.
28. Derek Hemy at the scoreboard of the continuous reliability test. Jan 1952.
29. "Lenaerts and Hemy triumphant!" Jan 1952
30. The display tubes on the console. Notice the bottom tube that allowed the entire store to be examined, 16 words at a time. Jan 1952
31. Gibbs, Hemy, Lenaerts. Jan 1952
32. Leo Fantl and Lenaerts. Jan 1952
33. Hemy, Gibbs, Fantl, Lenaerts. Jan 1952
34. Rack, unfilled, was to be filled with equipment to interface the STC gas tube converters and reconverters, later abandoned. 28 January 1953
35. Another view of the "co-ordinator" - Central control units. 28 January 1953
36. A close up of one rack, from the valve side.
37. Rack with covers in place.
38 -39. Wally Dutton. The lids of the delay line battery coffins can be seen in the foreground. 28 January 1953.
40. The control console. The upper right panel is an early Marginal test control panel. 28 January 1953
41. Laying a new floor on the RHS of the room after the STC equipment had been removed, and prior to permanent installation of the Hollerith punched card I/O equipment and tabulators. Dec 1953
42. General view in January 1953.
43. Rare view of the swinging gate construction of some part of the equipment installation by STC.
44. Equally rare view of 2 STC tape decks with endless loops of 1/4" tape in removable boxes. October 1953
45. STC tape decks. October 1953
46. Some of the gas trigger tubes in the STC equipment that gave so much trouble. There are single trigger tubes as well as the larger 10- cathode counting tubes in the photo. October 1953.
47. The STC Reconverter on left and the main LEO I power supply cables in background. October 1953.
48. A view down the centre of the room with STC equipment on left in October 1953 before the STC gear was removed.
49. General view of the STC decimal or sterling to binary converter. There were 3 of these on 3 channels each separately buffered. October 1953.
50. Another view of several racks of STC kit. The back rack contains the reconverter that reconverted binary numbers back to decimal or sterling form for recording on magnetic tape. October 1953.
51. Hollerith special tabulators printing 100 lines/minute on 100 columns all having 0-11 on every column. November 1953.
52. Hollerith Tab. Plugboard used to re-arrange output in any desired way on the line. In 2 buffer loads LEO I could print 70 characters anywhere on the line. The tabulator preserved the card listing facility. November 1953.
53. The control desks. Home made photo electric tape reader and teleprinter output. Notice reliability statistics on wall behind the I/O equipment. November 1952.
54. Another general view of LEO I. The flooring seen is 18 inches above the real floor, and conceals a mass of cables. 28 January 1953.
55. 200 card p.m. readers supplied by British Tabulating M/c Co.
56. An amusing view of an exploded 2 microfarad condenser. (LEO Gremlin 3 December 1953).
57 -58. The exploded condenser.
59-60. Further views of a similar component in good condition.
61 -62. Relaying floor in Calculator Room. December 1953.
63-64. Various views of the new floor being laid, Calculator Room. December 1953.
65. For the first public demonstration in January 1954 attended by numerous representatives of the national press, this roller blind caption was mounted on the ceiling. It was devised by Arthur Clements.
rolled down. The same again January 1954.
67. A more streamlined control desk to allow operations to work LEO I from the centre of the cluster of I/O equipment. September 1954.
68. Control desk. September 1954.
69. Photo taken outside the Mathematical Laboratory at Cambridge in 1948. Includes Don Willis, Ernest Lenaerts, John Bennett, Eric Mutch, Bill Renwick, Maurice Wilkes, David Wheeler, Ben Noble.
70. Group photo 1950.
71. Folder containing loose photographs :- a) - e) LEO output punch - taken at Letchworth 9.1.1963 f) - h) LEO II - (Lyons, Cadby Hall) - Peter Woods (standing) i) Inspection of Character Shaft on System 4 Line Printer. 5.2.1967 j) LEO II k) Michael Canton