The natural rivalry of former colleagues forced Sinclair to push the development of the ZX81 hard. Already conceived as a follow-up that would be cheaper to produce than the ZX80 - it would use fewer chips - but contain dedicated video circuitry to prevent the ZX80's screen flash.
The ZX81 was developed by a team led by SoC's chief engineer, Jim Westwood. Its Basic interpreter and OS was written by John Grant and Steve Vickers at Nine Tiles, a company contracted by Sinclair for the ZX80's software. A bigger Rom chip - 8KB to the ZX80's 4KB - allowed Grant and Vickers to extend the new machine's functionality considerably, in particular floating point maths and trigonometry functions.
SoC's Rick Dickinson designed the iconic casing. The look was based on the ZX80, but out went that machine's vacuum-formed cover in favour of superior injection moulding.
How it might have been: Rick Dickinson's early ZX81 design draft
Once again, SoC used the Z80A CPU and equipped the ZX81 with 1KB of memory. A 16KB Ram Pack add-on would later be offered, and become the source of much annoyance - but hilarity to owners of rival machines - because its poor fit ensured that any movement could cause it to lose electrical contact, crashing the computer.
Sinclair had said the ZX81 would be out in the Spring of 1981, and, pushed hard, the development team managed to do so. The ZX81 was launched on 5 March 1981. Around the same time, Science of Cambridge was renamed Sinclair Research.
Next page: Selling the ZX81
Doing down a rare success
I'm not sure anyone's claimed Alan Sugar as a visionary. There's loads of tales of his early days and some of the interesting bodges used to make Amstrad products 'better' - but that's a separate post.
As for Sinclair - yes, he was lucky, but he was in a market where there were hundreds of other people trying to be as lucky, and failing. It's easy to forget in these days of near-two party OS politics, that alongside the ZX81 and Spectrum were devices from Jupiter Cantab, Oric, Tandy, Commodore, Newbrain, Dragon, Elan, Atari, MSX and a dozen others - each completely unique and incompatible.
Sinclair's skill at the time was getting more bang for less buck than virtually any of his competitors. He pushed components beyond their limits, made use of quirks in their specs and pulled together innovative technologies to deliver something unique. It was a scattergun approach that had as many failures as successes, but before commoditisation removed much of the advantage, he was putting home computers into the home. There has to be huge credit to the teams that worked on the machines - from Rob Dickinson's wonderful industrial design through to the FPGA and OS that ran inside.
Of course the industry changed massively and that shook Sinclair, Acorn and most of the others back down to nothing. I'm not sure that makes them less significant, nor necessarily less visionary. Very few technology companies have survived from those early days to present times, and even those have had disastrous moments alongside the successes.
It's a huge pity that these days we're so risk averse and so keen to ridicule people who're willing to try something different that we have trouble producing such exciting technology. Hold an iPad in one hand and a ZX81 in the other and think what could have been.
I am typing a game lol
I still have mine!
It still works greats.
Two words to get fellow owners nostalgic:
Gawd bless ya Clive and all who sail in yer.