The Sinclair ZX Spectrum was launched in 1982 by Sinclair Research Limited, as a successor to the Sinclair ZX80 and Sinclair ZX81 home computers.

An 8 bit computer, based on the popular Z80 chip which had powered the ZX80 and ZX81, this introduced colour (8 colours) and sound to the home computer market.  It had either 16K or 48K memory as standard and relied on a cassette recorder for loading and saving programs.

Each key on the Spectrum's keyboard represented up to 4 different keywords, which allowed you to enter commands at the push of a button - although it could be confusing to remember the combination of keys needed for some of the more obscure commands.

The ZX Spectrum led to the first home computer boom with 1000s of software titles being produced and many companies selling new add-ons and upgrades.

The original Sinclair ZX Spectrum came with a fawn/light grey rubber keyboard, with an issue 1 circuit board which was infamous for having a smaller daughterboard to hold the extra 32K RAM (if installed) and what looked like a dead cockroach connected by various wires inside to overcome problems with its early ULA. That version of the ZX Spectrum is much sought after.  Later versions had all the memory on the main motherboard and also had a blue-grey keyboard.

Over 1,000,000 ZX Spectrum computers were sold throughout the World, with many clones appearing in Russia and South America.

Having seen the popularity of people adding after-market keyboards, Sinclair later released a ZX Spectrum+ with a full size keyboard, which was available as an upgrade to the original. 

The later ZX Spectrum 128 had a full sized keyboard, 128K RAM and an upgraded 128K operating system (which allowed you to enter commands one letter at a time) and has a heatsink bolted onto the side of the Computer (colloquially known as a toastrack).  Enhancements included the addition of an AY sound chip and MIDI out interface. This edition remains popular and sought after. 

This version was developed in conjunction with their Spanish distributor Investrónica and had an optional plug in numeric keypad (although these are now rare and never appear to have been marketed in the UK).  Oddly, the Spanish version of the ZX Spectrum 128 is not as compatible with add-ons as the UK version as it lacks a CLK signal from the Z80 on the edge connector.  The Spanish version can be identified by the fact that the 128 is in white, whereas on the UK version it was in red.

Once Sinclair Research Limited had sold the rights to the Sinclair range of computers to Amstrad, four new versions of the Spectrum were launched by Amstrad, which can be identified by a built in cassette deck (or disk drive).  These were:

• ZX Spectrum +2 (grey with built in cassette deck)
• ZX Spectrum +2A (black with built in cassette deck)
• ZX Spectrum +2B (black with built in cassette deck)
• ZX Spectrum +3 (black with built in 3" disk drive)

Unfortunately, the +2A and later models were not as compatible with existing software and their popularity waned, although the +3 remains a favourite amongst Sinclair fans.

The Sinclair ZX Spectrum computer remains popular amongst enthusiasts even today and continues to attract people seeking that retro feel and a simple way to learn how to program.  Programs and hardware continue to be developed for this humble computer.

More details about the ZX Spectrum including an archive of its software and hardware can be found at www.worldofspectrum.org