Retro Isle - Sinclair ZX81

Vital Statistics

Introduced March 1981
Retired: 1982
Price: £50 (in Kit form), £70 (Ready-assembled)
Quantity Sold: approx 1,000,000
Countries: UK and Europe (in USA, Timex-Sinclair TS1000)
Dimensions: 167 x 175 x 40 mm
Weight: 350g
Ports: Z80 bus, tape, video, PSU
Usable RAM: 1K (expandable to 64K)
Built-in ROM: 8K
Colours: 2 colours (black and white)
Graphics: 64 x 44 pixels, or text resolution of 32 x 24
Sound: none
Built-in Language: BASIC
Clones: TS-1000 (USA), Lambda, PC-8300, Power 3000 (Hong Kong)

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Sinclair ZX81 (1981)

What's it like today?

Fun Factor: 3/5
Rarity: Fairly common
Typical value: £30
Boxed & Mint: £80

The Sinclair ZX81 replaced the ZX80 in February 1981. This new machine now provided SLOW and FAST mode, which meant the ZX81 was capable of executing a program and writing to the screen at the same time (SLOW mode). The ZX80 only had FAST mode which could not do this. The 4K ROM included 30 new functions plus some new instructions to control a printer.

Because of better componentisation, the ZX81 was able to be sold for £30 less than the outgoing ZX80.

A US version of the ZX81 was marketed by Timex-Sinclair, called the TS1000. This varied only slightly, with 2K RAM instead of 1K, a shielded case, TV output on channels 3 or 4, and the screen was black on light blue background, instead of a white background.