Retro Computers - Sinclair ZX80 - Retro Computer

Sinclair ZX80
Getting a 'ZedEx' delivery

The Sinclair ZX80 was a home computer manufactured by Sinclair (formaly known as Science of Cambridge Ltd). The computer was released onto the UK market in 1980 - hence the name 'ZX80'.

The ZX80 was notable for being the first computer available in the United Kingdom for under a hundred pounds as it retailled at £79.95. For technophiles it was available in kit form where the buyer could assemble and solder it together - MacGyver still wasn't around to do this for you.

For mere mortals a ready built version (at a slightly higher cost of £99.95) was available for purchase. The ZX80 was a very popular machine straight away, and for some time there was a waiting list of several months of buyers for the machine.

The machine was designed by Jim Westwood and was based around a Z80 CPU with a pretty impressive clock speed of 3.25 MHz. It was equipped with 1KB of static RAM and 4KB of read only memory which held the Sinclair BASIC programming language, the editor and the operating system.

BASIC commands were not entered by typing them out (as Sinclair machine users would come to know over the next few years) but were instead selected somewhat similarly to on a scientific calculator. Each key had a few different functions selected by both context and modes as well as by use of the shift key.

Display was over an RF connection (connected to a household television), and program storage was possible using a generic cassette recorder. The video display generator of the ZX80 used minimal hardware plus a combination of software to generate a video signal. This was an idea that was popularised by Don Lancaster in his 1978 book The TV Cheap Video Cookbook and his 'TV Typewriter'.

As a result of this approach the ZX80 could only generate a picture when it was idle, yes only when it was sitting doing nothing - as in waiting for a key to be pressed. When running a BASIC program, or even when simply pressing any key on the keyboard, the display would black out momentarily while the processor was busy.

This made moving graphics difficult since the program had to introduce a pause for input to display the next change in graphical output. I did make creating your own indoor monochrome disco easy though by repeatedly hitting the space button whilst listening to Bony M.

A year later as the ZX81 was released, the 8KB ROM was also usable with the ZX80 which allowed those MacGyver types to upgrade their machine to 'almost' be a ZX81. It came supplied with a thin keyboard overlay and a ZX81 manual.

To Upgrade:
  • Take off the top cover of the ZX80
  • Pry the old ROM from its socket and carefully insert the new ROM
  • Add the keyboard overlay
  • Spin round three times at precicesly 15:03 GMT and pray to Lord Clive with the 'I love Sinclair mantra'

The upgrade would now be complete. This was quite a cool feature - showing intercompatibily between machine models.

It was also possible to reverse this process to remove the upgrade. Sinclair also produced RAM expansion packs for the ZX80. The original ZX80 RAM Pack held either 1BK, 2KB or 3KB of static RAM. Later on a model that held 16KB of RAM was released which used dynamic RAM chips (yes DRAM!)

The ZX80 was never a technical marvel. It had no sound whatsoever and no colours to speak of (monochrome display only). It was also never a cool looker - the tiny white plastic case with the one piece blue membrane keyboard on the front always looked ordinary.

On top of this it was not the most durable of micros and was also prone to bouts of overheating. BUT - it did bring computing into the homes of the UK at a reasonable price, and made computing available to those that were not techno-geeks or hobbysists.

It also provided the platform for Sinclair, who would go on to release more succesful machines over the next few years. Sales of the ZX80 reached somewhere in the region of 50,000 which was an unheard of number for the day. This contributed significantly to the UK leading the world in home computer ownership through the 1980s. Due to it's success the machine was also cloned quite alot, machines such as the MicroAce and the TK82 being two.

Owing to the unsophisticated design and the tendency for the units to overheat, surviving machines in good condition are sparse. If you want one be prepared to pay a few quid.

Give this machine a nod, it deserves it for what it did for home computing - a fine retro computer.

We recommend trying to pick up one of these machines.
Look at computers for sale online or even locally.

If you don't want to get hold of the real hardware then try and download an emulator and
download those classic games. Alternatively you could try and play them online.

MACHINE TYPE: Home 8-Bit Micro
RELEASE YEAR: February 1980
BUILT IN LANGUAGE(S): Sinclair Basic
KEYBOARD: Membrane keyboard, 40 keys, 1 SHIFT key
CPU: NEC 780C-1 (Z80 compatible)
SPEED: 3.25 MHz
RAM: 1 KB, 901 bytes available (upgradable to a then massive 64 KB)
ROM: 4 KB. Can be expended to 8 KB making it 'almost' a ZX81
TEXT MODES: 32 characters x 22 lines
GRAPHIC MODES: 64 x 44 dots
COLORS: Monochrome only
SOUND: Zilch
SIZE / WEIGHT: 21,9 (W) x 17,5 (D) x 4 (H) cm / 375 gr
I/O PORTS: Z80 Bus, tape, TV/RF video
POWER SUPPLY: 9v DC external PSU
PERIPHERALS: 16 KB RAM extension
PRICE: Kit model: £79.95 (UK, 1980) Assembled model: £99.95 (UK, 1980)

Retro Computers and classic games


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