2. The Von Neumann machine

Many years ago, in fact 1945, just after World War II, two mathematician-scientists independently proposed how to build a more flexible computer.

One was the British mathematician Alan Turing and the other was the equally talented American scientist John Von Neumann. Alan Turing had been involved with breaking the Enigma code in Bletchley Park using the 'Colossus' computer and John Von Neumann had been working on the Manhattan Project to build the first atomic bomb which needed a vast amount of manual calculations.

Up to that time, the war-time computers where 'programmed' more or less by rebuilding the entire machine to carry out a different task. For example, the early computer called ENIAC took three weeks to re-wire in order to do a different calculation. There had to be a better way.

The new idea was that not only should the data be stored in memory, but that the program processing that data should also be stored in the same memory.

This novel idea meant that a computer built with this architecture would be much easier to re-program. Effectively the program itself is treated as data.

This 'stored-program' architecture is now commonly known as the 'Von Neumann' architecture.