The ZX80 - Flashback To 1980

in computers •  last year

I love old tech, primarily because I come from a time when that old tech was new!

Trawling through eBay recently I came across a listing for a ZX80 computer. The action hadn't finished yet but already the bid price was at £493!

Holy crap!

Those things only cost £99.95 to buy new in the just post-dawn period of personal computing that was fashionable 1980.


An ad for the ZX80 from 1980

I was in university then, studying Physics with a view to becoming a professional astronomer.

In today's money, the price of of a ZX80 would be about £387 / $523, a not insignificant amount to a student in penury.

My First Computer

I remember scrimping and saving to be able to buy one. I shaved £20 off the purchase price by buying the computer in kit form and assembling it myself. Having messed about with building electronic circuits I figured I had enough soldering experience to be able to put this sucker together.

Luckily, my faith in my alibility was not ill-founded.

In the middle of 1980 I had a brand-spanking new, self-assembled, actually working home computer.

I spent a lot of time playing with it over that Summer, learning basic, zx80 machine code and the frustrations of working with a one-piece membrane keyboard.

Still, that's where I learned to program.


The ZX80 keyboard layout

I guess in a way it changed my life because when I went back to college in the autumn, I switched disciplines from Physics to the new fangled Computer Science in my second year.

That led me to learning Pascal, a long career as a computer programmer ensued and it's a language I still program in today. My LunarPhase Pro software was written using Borland Delphi 7 (their version of Pascal).

Anyway, back to the ZX80...

Back in those days, computers didn't have monitors. You connected them to more old-tech - your cathode-ray TV via the aerial socket.


A typical ZX80 setup - TV showing black-on white text. The TV in a space helmet look is someone's idea of "Cool". Source

Since the TV was a communal device, that restricted my computer use to mornings or afternoons.

On the TV, The ZX80 showed black text on an off-white background. As a shortcut for programming, keys on the keyboard would enter full Basic statements. You just had to type in the variable parts.

To give you an idea of how ancient this tech seems today, it had no floppy drives or internal storage. No, to save the programs you slavishly typed using its crappy keyboard, you had to connect it to a cassette recorder and store programs that way for later reloading.

Trouble is, it wasn't very reliable being dependent on the quality of the tapes and a machine that would play tapes back at a constant speed.

On more than one occasion I had to re-enter and re-save programs that I wanted to use. I eventually learned to use Chromium Dioxide tapes as they proved to be much more reliable.

Another limiting factor of the ZX80 was it's 1K memory. Yes, a whole 1K!

With that you could write and run a Chess program or run a power station as the ads for the computer screamed at the time.

Someone did manage to create a creditable Chess program in 1K. The power station thing was a bit of an exaggeration. :)

Christmas of 1980 I got the 1K memory extension module which doubled the ZX80's memory to a whopping 2K!

Then in 1981, Clive Sinclair released the updated and newer ZX81.

Since I couldn't afford a new computer, I went the cheap route. Sinclair released a new ROM with the ZX81 firmware that could be swapped out for the old ZX80 ROM. A new plastic overlay with the ZX81 keys overlay was provided as part of the package. In a high-tech solution, this was kept in place by 4 plastic tags.

So now I had a ZX80 converted to a ZX81.

But I didn't like that black text on white background look. It was hard on the eyes. And, besides, every time you clicked a key, the whole display flashed.

Ah yes, the good old days of computing.

So I bought another, unofficial, add-on for the ZX80 - a module (that I also had to assemble) that inverted the display so there was white text on a black background and if it still flashed, you'd hardly notice. To complete this innovative wizardry, the kit came with a switch that allowed you to alternate between the new and old-style displays.

Cool, eh!

A couple of months later I bought another memory extension module. In the space of a year or so, memory tech had moved on quite a bit and the 16K memory module I bought cost about the same as the 1K module from less than a year before!

It was very wobbly using what I think was a Centronics-style connector (for those who remember such things!)

I wrote my first sizeable astronomy software suite on that setup. I wrote other software too which got published in computer magazines of the time like Your PC.

Soon after, Sinclair released their next major step in computer technology - the ZX Spectrum.

I, however, went in a different direction, buying an Oric-1. I never owned another Sinclair computer.

Full Circle

So that brings me back to that eBay ad for a ZX80.

I'd retired the ZX80 and its gubbins to the attic in 1982 and not thought about it since.

Was it still there? Had it been crushed by the decades of crap that had been shoved into the attic in the meantime?

A little hunting about and some judicious moving of stacked gear...and there it was.

It was covered with 35 years of dust and grime. Finding its power supply and TV connection cable took a bit more work.


My Zx80/81 fresh from the attic. Maybe it doesn't look too grubby for being in neglected storage for 35 years?

I took another piece of kit from my collection of ancient tech - a 17" CRT portable TV, connected it to the ZX80, powered up the ZX80...and all I got was static on the screen.

Then I remembered that you had to tune a TV to a particular frequency in order to see the computer output, not like today when your TV auto-switches to display the output of a connected device.

I waited as the TV slowly scanned through the frequencies. Ghostly stations flitted by without the TV locking onto them. Not surprising as there are no analogue TV stations here any more.

And then, suddenly, there was a pure black screen. And sitting down in the left corner was the ZX80 cursor.

It's Alive!


My 37 year-old ZX80/81 still working

Frankly, I was amazed that the ZX80/81 had come back to life given its age and how poorly it had been stored.

I also found the original ZX80 ROM, the original 1K memory module, the 16K memory module...

...and some ZX80/81 books on programming and some of the magazines that had published my software listings.


some ZX80/81 programming books

So should I put this collection up for auction on eBay and maybe get a few hundred pounds/dollars (or maybe not given the fickle nature of auctions)?

Or should I safely pack everything away for posterity, taking the ZX80 out every 10 years to reminisce over how buying it changed the course of my professional life all those years ago...?

What do you think?

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