A German computer science student has built an electromechanical version of the iconic video game, Pong! In a tribute to computing pioneers, Niklas Roy renounced the use of semiconductors, transistors and the like, building a form of computer out of old telephone relays to handle the logic. The game has identical user features to the electronic original - the display is the same black field with a white "ball" and two paddles, control is by joystick, points are counted up by two counters, and it goes - well - "pong!"
The workings are obscenely complicated, as the game is actually played twice - once by an intricate assembly that contains the actual bats and balls, and then again by the markers on the display that represent their movement. It's a fine reminder of just how insanely difficult anything like this was until comparatively recently. Some very serious things were done, though - the RAF experimented with a computer constructed from telephone exchange technology to calculate interception vectors from radar data in the 1930s, until Henry Tizard realised that a simple mental method would do better. Later, at the end of the 1960s, the Hawker Siddeley Trident airliner had a crude moving-map navigation display, portraying information from radio-navigation instruments as a position on a chart. Unlike today's systems, though, "moving map" should be read literally - it was an actual paper chart on rollers, which unsurprisingly frequently tore or tangled.
What Roy's mechanical video game reminds me of most of all, though, is the very dawn of computing. In action (you can find the video here) it looks like nothing other than a power loom. The very first data processing machine, of course, was Jacquard's loom with its patterns on punched cards, that inspired Charles Babbage. The cards, of course, remained a current form of data storage until relatively recently.