After the modest but encouraging success of the MK-14 (initiation board with hexadecimal keyboard), Sinclair (at the time Sciences of Cambridge) decided to develop a slightly more advanced computer.
The ZX-80 is regarded as a pioneer system in micro-computing as at the time the only available computers were kits for hobbyists like the MK-14 or more expensive systems intended for education or research such as the Tandy TRS-80 or the Commodore PET.
The ZX-80 inaugurated the transition between the hobbyist world and the consumer electronics by proposing a true computer in its case for less than £100.
Technically, the ZX-80 is not a revolutionary system but is rather the result of a search for economy through the choice of the components, starting with the membrane keyboard, or the RAM memory limited to 1kb. The operating system, the editor and the Basic interpreter fit into the 4kb of the ROM !
The ZX-80 met some success with nearly 70.000 machines sold in less than one year, announcing the future success of the ZX-81 and at the same time the birth of a new major actor in the micro-computers world : Sinclair Computers Ltd.
Malcolm Ramage adds:
The rom in the ZX80 was the basis for the ROM of the ZX81, with a few new commands and enhancements. The Spectrum ROM was based on the ZX81 ROM, with extra commands for colour in basic and new routines in ROM for the new colour screen modes.
Almost all ZX80 BASIC programs can be run on a ZX81 or Spectrum without any modification.
Further information from Watz (Germany):
it was possible to buy a new ROM (50 EUR) and replace it with the old ZX
80's. You got all the function of the ZX 81 - exept the SLOW mode. Everytime something ZX 80/81 moved the screen went black for a moment... Very nasty... Pain for the eyes...
The ZX 81 uses the TV blanking interval for the calculation (so the speed goes down to ca. 25% FAST).
All peripherals must have a very special Sinclair interface, Joystick, printers... I bought a Seikosha GP 50 (unihammer - means one needle making awful noise when printing), and 10 cm broad normal paper, for 204
EUR) with this special interface.
Marty Quire remenbers:
I remember buying the ZX-80 for $99 in "kit" form. When it arrived I put the circuit board into the case & snapped the cover on...that assembled the kit!
One visionary thing about this computer was that keywords of the BASIC interpreter were assigned to the keyboard. It was essentially impossible to type a syntax error, since the keywords wouldn't be added unless they were in the right order.
There were no graphics modes on the ZX-80, but it had graphics characters on the keyboard, displayable with the print command. The character set included a square made up of all 16 combinations of 2x2 fat pixels. This could be used to form a low resolution graphics mode. This character graphics mode formed the basis of the plot commands supported in the ZX-81.
END OF PRODUCTION
BUILT IN LANGUAGE
Membrane keyboard, 40 keys, 1 SHIFT key
NEC 780C-1 (Z80 compatible)
1 KB, 901 bytes available (upgradable to 64 KB)
4 KB. Can be expended to 8 KB, thereby making it almost a ZX81