History Snapshot: 1981 The Sinclair ZX81

The Sinclair ZX81 was the first popular UK home computer. Launched in 1981, it had many features that ensured its success:

  • it was cheap – you could buy it for £69.95, or if you wanted to built it yourself you could get it for £49.95
  • it looked great – unintimidating and even friendly
  • it attached to your TV which it used as a monitor
  • it could be bought from shops in the high street like WHSmith
  • it had it’s own semi intuitive BASIC programming language that you could  actually use
  • programs could be written, stored and retrieved from standard audio cassettes

Having no moving parts – the ZX81 featured a touch style membrane keyboard and was switched on and off by attaching or removing it’s power supply. Whilst other computers aimed at the home user market historically preceded it – notably the Commodore VIC20 and Texas Instruments TI-99, it was the ZX81 that was able to successfully appeal to not only hobbyist users but also much of the UK public. It was the ZX81’s introduction that sparked the massive adoption of computing in the UK, causing the home computing boom that began in the early 1980’s.

The ZX81 came with 1K of internal memory which it shared with it’s graphic display – this made programming the ZX81 tricky as any sort of complex program required more that 1K of memory to run. However, with clever coding much could be done with 1K as was demonstrated by David Horne’s 1K ZX Chess – a decent chess program that used just 672 bytes of RAM. Sinclair introduced  a 16K RAMpack expansion for the ZX81 which was also popular and allowed many users to write far more complex and useful programs.


The success of the ZX81 gave the Sinclair team the confidence to produce their next computer, the ZX Spectrum, a machine that was probably the most significant home computing development of the 1980’s. More about the Spectrum in a future post.

Further reading: ZX81 page at OldComputers.net