Sinclair ZX80
From Free net encyclopedia
Image:ZX80.jpg The Sinclair ZX80 was a home computer brought to market in 1980 by Sinclair Research of Cambridge, England. It was notable for being the first computer available in the United Kingdom for under a hundred pounds (a pricetag of £99.95, to be exact). It was available in kit form, where purchasers had to assemble and solder it together, and as a ready-built version at a slightly higher cost for those without the skill or inclination to build their own unit. The ZX80 was very popular straight away, and there was for some time a waiting list of several months for either version of the machine.
The machine, designed by Jim Westwood, was based around the NEC μPD780C-1 CPU (a Zilog Z80 clone) @ 3.25 MHz, and equipped with 1 KB of static RAM (expandable to 16KB using a separate memory pack), and 4 KB ROM containing the Sinclair BASIC programming language, editor, and "OS". BASIC commands were not entered by spelling them out; instead, the commands were selected rather like they would be on a scientific calculator — each "key" had several different functions activated by use of several modifier (shift) keys.
Display was over a RF connection to a household television, and simple offline program storage was possible using a cassette recorder. The video display generator of the ZX80 used very minimalist hardware plus a combination of software to generate a video signal. As a result of this approach the ZX80 could only generate a picture when it was idle, i.e. waiting for a key to be pressed. When running a BASIC program the display would, therefore, black out. This prevented moving graphics etc. The later ZX81 improved on this somewhat because it could run in a 'slow' mode while creating a video signal, or in a 'fast' mode without generating a video signal (typically used for lengthy calculations).
A ZX81 8K ROM was available to upgrade the ZX80 and cost around 20% of a full blown ZX81. It came with a thin overlay keyboard and ZX81 manual. Simplay taking off the top cover of the ZX80 and prising the old ROM from its socket and carefully inserting the new ROM and adding the keyboard overlay, the ZX80 (now ZX81) would now function identically to the proper ZX81 except for SLOW mode, and this was purely down to hardware differences. The process was easily reversed to get the ZX80 back to its old self.
The ZX80 1KB memory could be expanded by a 3KB RamPac. There was no upgrade for the integer only arithmetic however, nor the monochrome display.
The machine was mounted in a tiny white plastic case, with a one-piece blue membrane keyboard on the front; it owed its distinctive appearance to industrial designer Rick Dickinson. There were problems with durability, reliability and over-heating. The entire system was about the size of two paperback books placed beside each other. Crude it might have been, but the ZX80 was a true innovator and it kick-started the 1980s home computer craze in the UK. It was superseded by a number of other Sinclair machines, notably the Sinclair ZX81 and the very successful ZX Spectrum.
Sales of the ZX80 reached about 50,000 - an unheard of number for the day which contributed significantly to the UK leading the world in home computer ownership through the 1980s. Owing to the unsophisticated design and the tendency for the units to overheat, surviving machines in good condition are quite uncommon and can fetch high prices by collectors.
| Sinclair computers, derivatives, and clones (ZX80/81, ZX Spectrum, and QL clones) |
|
By Sinclair Research and Amstrad: ZX80 |
ZX81 |
ZX Spectrum, Spectrum+, Spectrum 128K, +2 and +3 (the latter two by Amstrad) |
Sinclair QL |