Many quips and anecdotes from people working on and with early machines at the Computer Lab (initially the Mathematical Lab).
EDSAC 1 and after - a compilation of personal reminiscences
EDSAC was built in a room on the top floor of a building that was once the dissecting room of the Cambridge University anatomy school. This historical association brought with it an advantage and a disadvantage. The advantage came in the form of a large goods lift that had been designed to carry two cadavers. The disadvantage became apparent in the summer when the formalin (used to preserve cadavers) that had impregnated the floorboards over the years was vaporised by the heat
1949, May 6th
Machine in operation for first time. Printed table of squares (0-99), time for programme 2 mins 35 sec. Four tanks of battery 1 in operation.
Dijkstra notes:
My greatest scientific excitement was probably caused by the subroutines E2 (for the exponential function) and L1 (for the logarithm), E2 because it was so ingenious, and L1, because it was so simple and such an eye-opener. (It still is.)
It is no exaggeration to say that those three weeks in Cambridge changed my life!
John Lindley recalls
dropping the inside out of one of J.C.P. Miller’s precious Prime Number tapes and having somehow to disentangle it without wrecking it. Life is much simpler in some ways these days.
Karen Sparck-Jones remembers
As most users were not allowed near the Titan (shut away in its own shiny room) we submitted our jobs by putting paper tapes in plastic bags along with colour-coded tickets e.g. pink for large jobs (30 minutes estimated time, or needing 3 magnetic tapes). These bags were hung on hooks on a board outside the Titan Room.
There was a cabinet with copies of library routine tapes (on green paper) e.g. RR10 - read integer, or PR10 - print integer, for copying into one’s own program tapes.
Roy Bayley:
With Titan came two company engineers, Johnny and Gareth, whose task was to progress the Maths Lab team up the learning curve. Any readers around the Lab at this time will remember their well-deserved reputation for sinking large quantities of beer. Indeed, Sid Barton and I were amazed how they could return from a liquid lunch at the Eagle, having had the odd pint or five, stand swaying gently in front of the Engineers Console and still give sound advice on fixing faults. Faults that Sid and I were struggling to understand when sober!
Titan was a large asynchronous computer, consisting of 6 racks, with approximately 300 boards per rack. It had thousands of germanium transistors, tens of thousands of diodes and other discrete components. Each board carried only a small amount of logic, so fault finding by changing boards was of limited use. To fix faults the engineers needed to understand the voluminous computer logic and be able to adapt the test software to diagnose problems. It was a good learning experience.
Jennifer Leech:
As a research student I became an authorised user, allowed to use the machine alone and switch it off. There was one unbreakable rule - NEVER switch off the ‘oven’ which kept the mercury memory tanks at a fixed temperature. One night the machine stopped working and I became aware of an ominous smell of burning. I tracked this down to the oven motor, which was dripping oil on to the floor. I switched it off, fearing excommunication at least, but I wasn’t held to blame.
There were several levels of machine use authorisation - allowed to use the machine under supervision, allowed to use it alone and switch it off, and allowed to switch it on. Plus one unofficial higher level - to achieve enough confidence to turn J.C.P. Miller off the machine when his time had run out and it was one’s own turn. I think I reached that level in the end.