The ZX81 was revolutionary when it was launched in 1981. Although it was quite basic, lacked sound, colour or even lower case characters it was at a fraction of the cost of its contemporaries.

Part of Sinclair’s cost cutting was to make the ZX81 work with analogue TVs rather than needing a dedicated (and expensive) monitor. With analogue TVs becoming rarer, vintage ZX81s need a bit of modifying to output composite video.

Fortunately there are a lot of easily available boards that can be soldered in place of the existing TV tuner.