The Amstrad Spectrum Computers

When Amstrad acquired Sinclair Research's computer business in 1986, the future of the ZX Spectrum was far from certain. The Spectrum had already established itself as one of Britain's most successful home computers, but the market was changing rapidly and Sinclair's original machines were beginning to show their age. Amstrad's arrival brought new investment, new hardware and, eventually, a new generation of Spectrum computers that would take the range into the final years of its production.

The ZX Spectrum +2

The first Amstrad Spectrum was the ZX Spectrum +2, introduced in 1986. Rather than simply producing another version of the existing 128K Spectrum, Amstrad redesigned the machine around a new case which incorporated a built-in cassette recorder, making it a much more complete home-computer system.

The +2 retained the Z80 processor and the basic architecture of the 128K Spectrum, including its 128K of RAM and AY-3-8912 sound chip, while replacing the separate external cassette recorder with an integrated unit. The new case also provided a substantially improved keyboard, joystick connections and a more conventional appearance than the original rubber-key Spectrum.

For many users the +2 represented a significant improvement in everyday use. Loading software was simpler, the keyboard was considerably more robust and the built-in cassette recorder gave the machine a much more integrated appearance. At the same time, however, the machine remained recognisably a Spectrum, retaining compatibility with the enormous existing library of Spectrum software.

The +2 also marked an important change in the history of the Spectrum because it was the first model produced under Amstrad's ownership. Sinclair's name remained prominently associated with the machine, but the design, manufacturing and commercial direction were now controlled by Amstrad.

The ZX Spectrum +3

The next major development was the ZX Spectrum +3, introduced in 1987. This was a much more ambitious redesign, replacing the cassette recorder with a built-in 3-inch floppy disk drive and introducing a new disk operating system known as +3DOS.

The +3 retained the basic Spectrum architecture but incorporated substantial changes to the hardware and software required to support disk storage. The machine could load and save programs considerably faster than a cassette-based Spectrum, while the disk system also made it possible to work with larger programs and data files in a way that was much more practical for serious applications.

The new machine was accompanied by +3 BASIC, which extended the traditional Spectrum BASIC with commands for working with the disk system. The operating system and disk interface represented a significant departure from the relatively simple cassette-based environment of earlier Spectrums, although Amstrad continued to provide a Spectrum mode for running much of the existing software library.

The +3 therefore represented something of a crossroads for the Spectrum. It retained the identity and compatibility that had made the machine successful while attempting to move the platform towards the disk-based computing environment that was becoming increasingly common.

The +2A and +2B

Following the introduction of the +3, Amstrad went on to develop the ZX Spectrum +2A, retaining the integrated cassette recorder of the original +2 while adopting the newer hardware design that had been developed for the +3. The +2B followed as a further revision of this design, continuing the evolution of the Amstrad-built Spectrum range.

Although these machines looked very similar to the earlier +2, internally they were significantly different. The newer Amstrad hardware reduced the number of separate components required and incorporated changes that had first appeared during the development of the +3. This made the +2A and +2B closer relatives of the +3 than their model names might initially suggest.

The cassette recorder remained the defining difference between these machines and the +3, allowing Amstrad to offer a lower-cost Spectrum while retaining much of the newer hardware design. For users who already had large cassette software collections, the +2A and +2B therefore provided a familiar method of loading and saving programs while benefiting from the later Amstrad engineering.

A New Generation of Spectrum Hardware

The Amstrad machines represented more than a cosmetic change to the original Sinclair designs. Across the +2, +3, +2A and +2B, Amstrad progressively redesigned the Spectrum hardware, moving away from the construction methods used in Sinclair's earlier machines and towards a more integrated design.

The changes can be seen throughout the machines, from their keyboards and cases to their power supplies, expansion arrangements, sound hardware and memory systems. The +3 went further still by incorporating a disk drive and a substantially revised operating environment, while the later +2A and +2B brought much of that newer hardware back to a cassette-based machine.

This gradual evolution is particularly interesting because the machines continued to present themselves as ZX Spectrums throughout the process. To the casual user, a +2A could appear to be little more than another version of the familiar +2, yet underneath the case it belonged to a considerably later generation of Amstrad hardware.

The End of the Spectrum?

By the end of the 1980s the Spectrum's position in the computer market had changed considerably. Newer computers were becoming more powerful and affordable, while the Amstrad-built +2A, +2B and +3 represented the final development of the original Spectrum family. It would have been easy to assume that the story was coming to an end.

Not so. The Spectrum found a new and particularly enthusiastic following in Eastern Europe, where the relatively inexpensive hardware and enormous existing software library made it an attractive computer long after it had begun to disappear from the mainstream computer market in Britain. Spectrum-compatible machines and clones appeared in several countries, while a new generation of programmers and enthusiasts continued to develop software and hardware for the platform.

The arrival of PC-based ZX Spectrum emulators opened up the machine to an even wider audience. For people who had never owned a Spectrum, emulation provided an easy way to discover its software, while for those who remembered the original machine it offered a convenient way to revisit it without needing the original hardware.

Emulation also helped create a new generation of Spectrum hardware enthusiasts. Rather than simply preserving existing machines, enthusiasts began designing their own hardware, often using modern components to reproduce or extend the capabilities of the original computer. Projects such as Pera Putnik's 8-bit HDD interface demonstrated how the Spectrum could be connected to modern storage technology that would have been prohibitively expensive and impractical for most home users in the 1980s. The ZX Spectrum Harlequin recreated the Spectrum's hardware using readily available modern ICs. Its origins can be traced to Chris Smith's book The ZX Spectrum ULA - How to Design a Microcomputer, which examined the operation of the original ULA and showed how its functions could be reproduced using easily obtainable logic chips rather than the custom ULA itself.

The interest eventually moved beyond home-built projects and into commercial products. The Recreated ZX Spectrum provided a modern recreation of the classic machine, while the ZX Spectrum Vega and ZX Spectrum Vega+ offered compact modern systems designed around the Spectrum's software heritage. The ZX Spectrum Next combined the character of the original Spectrum with substantially expanded hardware and capabilities.

And the story continues. Products such as The Spectrum have brought the familiar Spectrum experience to a new generation, showing that the machine still has an audience more than four decades after the original ZX Spectrum was launched.