Something special happened in the UK at the start of the 1980s and it  altered the  face of computing as we know it. You  may  be  of  the opinion that all that ever happened in the past was Apple and IBM, but not so. In the UK there was an explosion of machines unlike any other before or since. To mark the 40th anniversary of the ZX-81 we look again at these remarkable micros.

Before 1980 most personal computers were S100-based modular machines - big, complicated and expensive. The newer breed of all-in-one machines such as the PET, the Tandy TRS80, and the Apple II were just becoming available, but even these  budget  machines, which must have appeared an unbelievable bargain in the US, seemed far to pricey for the average UK user.

To put things in context the original retail price of the  Apple II  was US$1,298 (with 4 KB of RAM) and US$2,638 (with the maximum 48 KB of RAM). The price in pounds wasn't a much smaller figure and to allow for inflation think of it costing around  £5,000 in today's money. The price tag for a PET in the UK was around £600 and the Tandy TRS-80 £500 and the UK market was really looking for something that cost at most £200/$300 and preferably less than £100/$150 for an entry level machine.

This resulted in the single-board "naked" PC style of machine, such as the NASCOM, being very popular. This was fine as long as you were interested in electronics, or at least not frightened by it, but there was no real prospect of this sort of machine being acceptable to the mass market.

The point is that while there were machines suitable for home use, the home buyer had no real confidence that they should buy a computer and £500 plus was a lot to risk on the chance that it might be useful or fun.

ZX80

All of this changed very suddenly in the February of 1980 when the Sinclair ZX80 burst onto the market.

This was something quite new and different. Science of Cambridge, which is what Clive Sinclair's computer company was initially called, had already produced a low cost microprocessor trainer called the MK14 but the ZX80 was a real computer - it had a case!

The ZX-80

As well as having a case, It came complete with a full keyboard, used a TV as a monitor and you could have it all for £79.95 (about £300/$420 in today's money) . Of course it wasn't quite as good as this makes it sound. In particular, if you bought it at this price you had to put your ZX80 together from a kit. A fully finished machine cost £99.95 which was still very reasonable (£385/$550 in today's money).

The low price was achieved by making it's Z80 processor do more or less everything. It was the keyboard controller, video generator and tape interface. This made it cheap but it had its drawbacks. For example the video display vanished whenever the processor had something else to do - which included hitting a key which made the screen flash.

It also only had a non-standard integer-only Basic. But it all did work and in a very small, self-contained package.

It started the move towards self contained small computers that were suitable for home use even if you didn't know anything about electronics.

Acorn Atom

At about the same time as the ZX80, Acorn, who also already had a simple 6502 module system, announced the Acorn Atom.

This was a complete machine but nowhere near as innovative as the ZX80. The Atom used a 6502 processor and, like the ZX80, only used integer Basic but it was expandable. It may have been more like a traditional machine but it cost £120 as a kit and £150 built, which made a lot of people think twice about it. Of course its design lead on to the BBC Micro.

ZX81

 The ZX-81

After the ZX80 and the Atom things went quiet for over a year. There were new machines but all either up-market £1000 plus systems or single-board naked machines.

Then at the start of 1981 Sinclair announced the ZX81, its successor to the ZX80. This used the same innovative design as the Z80 but it solved most of its problems - no flashing display, a floating point Basic - and it cost less.

At £50 for a kit, it was the first machine that you could afford to buy just to find out if computing was as interesting and as fun as it was supposed to be. What is really amazing is the fact that the tiny machine didn't put a generation off the subject!

Acorn too had a new machine that they were about to launch but they were hanging fire because of the BBC’s attempt to meddle in the market. The BBC had decided to produce a series of TV programs about the micro and educational material to go with it. The really amazing part of this fairly straightforward decision was that they planned to launch a BBC Micro - a machine that the BBC's course could be based around. Of course the machine wasn't going to be designed by the BBC, just endorsed by it.

Sinclair probably decided to sell as many ZX81s as possible to the world before the October 1981 launch of the BBC micro and the start of the television series in January 1982.