EDSAC manufacture in Cambridge

In recreating the EDSAC computer, a surprising amount of mechanical engineering is required. EDSAC engineering was originally done by hand in the 1940s, but for the EDSAC Replica Project modern Computer Aided Design -- a direct descendant of EDSAC -- is being deployed.

The machine occupies three rows of metal racks taking up 15 feet square and six feet high. Each rack has twelve or so shelves or 'chassis' of electronic circuits. Each shelf generally comprises a functional unit making up the machine such the the central Clock Pulse Generator, five Digit Pulse Generators and so on. The circuits use thermionic valves sitting in holders fitted to the top of each chassis and the other components such as resistors, capacitors and inductance coils are soldered together on the underside.

In the original machine the chassis were all made by hand in the Cambridge University Mathematical Laboratory workshops. For the EDSAC Replica we are using modern Computer Aided Design and Manufacturing methods to produce them.

The video shows how Teversham Engineering has reconstructed the design of the racks and chassis from photographs and makes them using modern numerically controlled machines in its factory.

There are some parts of EDSAC however that still have to be hand made, and the second part of the video shows the Project Manager's garden workshop when he is making tag strips (the 1940's equivalent to modern printed circuit boards) and formers for winding wire coils used as 'lumped delay lines' to adjust the timing of signals passing through the computer.