Sinclair ZX81

The ZX81 was the successor of the ZX80 and one of the cheapest home-computers.


One of the things that made the ZX81 so cheap was the touch-sensitive

membrane keyboard. There were only 4 chips (in some ZX81 5 chips)

working inside: The CPU, ULA (logic chip),

8 KByte rom and 1 KB ram. There was not a graphic chip so the CPU

had to do the job.

The ZX81 was also available as a DIY kit. In some countries the ZX81 was

sold as the TS1000.

The keys of the ZX81 had 5 different meanings e.g. if you press 'P' the

ZX81 will print 'P' or 'PRINT' depending on the situation the key is pressed.

There were two peripherals: A cassetterecorder (not a special one: you could

use every walkman) and a special ZX printer. It was necessary to find

the right volume for the cassetterecorder to save programs to cassette

(it was somewhere in the middle).


Today there are still many ZX81-enthusiasts around the world. In Germany

there is a user-club only for the ZX81 and its clones: The ZX-Team. They

are still developing new hardware extensions like an adapter for the

Commodore 1541-diskdrive, coulour graphic and sound.

The ZX81 is still far better than a PC for people who want to understand

how a computer works.

A ZX81 can be updated to the following configuration:

  • Colour and high-res graphic (ca. 256*182)
  • Sound
  • 1541 floppy disk
  • RAM expansion to 1 MByte (!)
  • Links:


    CPU/Clock speed:Z80A/3.58 MHz - 8-Bit

    ROM:8 KB

    RAM:1 (32) KB


    Text display:32*15




    Operating system:compatibel with ZX80

    Languages:Basic, Assembler

    Interfaces:Expansion, Cassette recorder, TV

    Storage:Cassette, Disk (5.25"")


    Size (in mm):167*175*40

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    (C) 2001-2014 by Matthias Jaap. Last update: 31/12/2014.