The first computers were built during World War II to attempt to decode German coded signals.

From this early work sprung "EDSAC" (Electronic Delay Storage Automatic Calculator) the first truly programmable computer, built at Cambridge University (UK) in 1949.

This computer, shown in the background above, was used by mathematicians for research and learning. It contained 3000 valves and consumed some 12kW of power!

History was made in 1952 by AS Douglas, a young PhD student, when he used it for another purpose: he programmed it to play noughts and crosses. The computer used a cathode ray tube to display its output, which means this was the very first video game in the world.

In the mid 1960s both Sydney and Melbourne technical museums attracted large crowds with a "computer’ which played noughts and crosses against a human opponent.

In 1968, when the author was aged 24, he and a friend built a machine using 70-odd telephone relays and a uniselector to play the game.

A uniselector, by the way, is a rotary, solenoid driven, fifty position switch. They were commonly used in automatic telephone exchanges at the time and were even found in some older exchanges until quite recently, when first solid-state devices and then microcontrollers took over. In a busy telephone exchange, the noise of the uniselectors switching back and forth following the numbers dialled on a phone perhaps ten kilometres or more away was quite deafening!

Fig.1: not a Uniselector in sight (or even hidden!). The PIC chip does all the work of the mechanical monster of 40+ years ago - and this OSCAR is much easier to build.