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Gone but Not Forgotten: Sinclair Computers

For many, the 1980s was the golden era in home computing. Low cost 8-bit systems brought arcade games to the masses, while offering the ability to handle basic office tasks at the same time. Companies such as Acorn, Commodore, and Dragon rapidly become household names.

And fighting for sales amongst them all, was a tiny British company. Their computers were cheap and basic, but helped give rise to the world of bedroom programming and some very familiar game developers. Join us, as we reminisce about the brief life of Sinclair computers.

The early battles for success
British inventor and entrepreneur, Clive Sinclair, set up his first company, Sinclair Radionics Ltd. in 1961, selling a variety of electrical and electronic products for the home. It performed well for over 10 years, thanks to the buoyant economy at the time, and a highly successful product — a digital calculator, called the Sinclair Executive.

Unfortunately, disastrous flirtations with the development of portal televisions and digital watches drained the bank balance, resulting in the company closing its doors. But Sinclair didn’t let this get in the way of his desire to innovate and by the late 1970s, he was back again, in the form of Science of Cambridge Ltd.

Encouraged by developments made in the microprocessor world, his tiny group of engineers created the MK14 — one of the first home computers made in the UK (sold in kit form). Its unexpected success proved that there was a market for this product, and following another change in the company name (Sinclair Computers Ltd), they had their next big success.

Despite its flaws, the ZX80 was very popular. Source: Wikipedia

By today’s standards, the ZX80 might seem like a complete joke, but $230 (£100) in 1980 got you an 8-bit 3.25 MHz Zilog Z80 clone processor, 1 kB of 8-bit wide SRAM, and 4 kB of ROM — a surprising amount of technology for that budget.

It did come with some drawbacks, though, due to the cost cutting: there was no audio output, nor any real hardware to create the video signal. The visual output was mostly handled by the Z80 chip, in an interrupt mode; so pressing any key on the pad or executing any code would result in an momentary loss of the screen!

The visual output was mostly handled by the Z80 chip, in an interrupt mode; so pressing any key on the pad or executing any code would result in an momentary loss of the screen!

Despite these issues, the ZX80 repeatedly sold out, and put Sinclair firmly on the map, as a serious competitor in the home computer market.

In 1981, the company was renamed yet again to become Sinclair Research Ltd, and shortly after they launched the ZX80’s successor, the ZX81.

Much of the architecture and specifications remained the same, but it was cheaper to manufacture (using an uncommitted logic array chip, ULA, to replace a raft of logic components) and had double the ROM, enabling a better instruction set to be used. The screen blanking problem was gone, and there was even basic audio output.

The ZX81 was somewhat rushed, and had reliability flaws, but it cost 30% less than its predecessor — naturally, it sold by the proverbial bucket load, and earned Sinclair Research a small fortune. And the best was yet to come.

Sinclair’s zenith
The biggest criticism of the ZX81 was the paucity of RAM — just 1 kB of it, although it could be expanded, by use of a very wobbly add-on board, to 16 kB or 56 kB. For games and other graphics-based programs, the restrictive monochrome 64 x 48 pixel resolution was also commonly berated.

Some clever programming could get around the resolution limitation, but what was really needed, was more capable hardware. Sinclair Research was aware of this, and their answer came in April 1982: the ZX Spectrum.

Two versions were available that differed only in price and the amount of memory installed: 16 kB for $220 (£125) and 48 kB for $310 (£175). This was a substantial increase in price over the ZX81, but the various improvements justified the rise.

Like its predecessor, the Spectrum used a ULA to perform many of the standard functions, but this time it provided a real hardware solution for creating the frame raster. This was previously handled by the Z80 processor and freed from that task, it could be dedicated entirely to executing programs.

It also gained a small clock improvement to 3.5 MHz — altogether, the Spectrum’s processing capability was roughly four times better than the ZX81. The hardware raster was also much higher in resolution (256 x 192 pixels) and was finally in color.

This aspect was handled in 8 x 8 pixel blocks of just 15 possible colors: black, and two levels of brightness for 7 base colors. Unfortunately, due to memory restrictions, only a single foreground and background color could be set for the whole block.

The effect of this was something called attribute clash, where changing just one pixel in the block would switch the rest to the same color, leading to undesirable visuals, especially in animation.

Early game developers for the platform didn’t bother to avoid the problem, but later titles demonstrated some ingenious tricks to mask it.

The ZX80/81’s use of SRAM was gone, too, replaced by 2.7 MHz 1-bit wide DRAM. While not as good as SRAM, the change was necessary to increase the memory footprint and still keep the cost down. Other aspects of the Spectrum pointed to sale price restrictions, the most notable of which was the keyboard. The rubber block keys were considered to be unpleasant to use, and the membrane underneath often developed faults.

Home computers of this era were almost entirely assembled by hand, leading to the occasional problem with soldering quality, and misplaced or incorrect components being fitted. But it didn’t really matter — Sinclair had another huge hit on their hands and revenue almost tripled within 2 years (aided by a significant price drop 12 months after launch).

Over a period of four years, the ZX Spectrum was updated twice: the Spectrum+ arrived in October 1984 (same internals with a better keyboard) and the Spectrum 128 in the latter months of 1985. This version offered 128 kB (in the form of two 64 kB switchable banks), a dedicated audio chip, and more ports for expansion and video options.

It was also to be Sinclair’s final home computer — for all its popularity, the Spectrum couldn’t save the company from suffering crippling losses. So what exactly went wrong?

It was all so brief
In 1982, Sinclair agreed to a licencing deal with Timex Corporation, an American producer of clocks and watches. They were already the primary manufacturer of Sinclair’s product (the production line being based in Dundee, Scotland) and the boom in home computing tempted the firm to try their hand at expanding their product portfolio, to offset falling sales in their main sector.

The joint venture, labelled Timex Sinclair, did more than just sell rebranded ZX81 and Spectrum machines — instead, Timex attempted to enhance the base platform, either in the form of additional RAM, better chips, or additional expansion systems.

How much income this generated for Sinclair is uncertain, but poor sales in America forced Timex to withdraw from that region by 1984, although they carried on in other countries until the early 1990s.

Where the ZX Spectrum was the best selling home computer in the UK, Timex Sinclair machines didn’t sell anywhere near as well. The likes of Commodore and Atari were far more competitive on price and product development. In 1985, the former company released the Amiga 1000, a very powerful (and expensive) machine.

Its capabilities were far superior to the likes of the lowly ZX Spectrum and was well received in business sectors. Sinclair Research had tried to penetrate the same market a year earlier, with the Sinclair QL (‘Quantum Leap’).

Both the Amiga 1000 and the QL used a Motorola 68000 series chip for the main processor. This was a hybrid device: it had 32-bit registers and the same size internal data bus, but the memory address bus was 24-bits, the logic units and external data bus were 16-bits wide.

Despite this complexity, the Motorola processor was easy to work with and very capable. For the QL, Sinclair used the cheaper 68008 version — the clock speed was an impressive 7.5 MHz, but the address and external memory buses were narrower, at 20 and 8 bits, respectively.

The base price for this computer was $560 (£400), sporting 128 kB of RAM, and twin Microdrive slots (a proprietary magnetic tape storage system). It should have been very tempting for smaller firms with a tight budgets or government bodies looking to cut costs. However, the whole project was both rushed and delayed, and launched with numerous bugs and reliability problems.

It also looked almost identical to the ZX Spectrum+, which was universally recognised as a gaming computer for children. Unsurprisingly, it sold poorly and was officially discontinued after just two years.

Sinclair Research had also tried to develop and sell other products: a wrist watch with a built-in FM radio, an electric tricycle, and a pocket television, but they were all commercial failures and pushed the firm into bankruptcy.

With Clive Sinclair losing millions of his own money, the inevitable happened in 1986 — the Sinclair brand name and all products were sold to another British electronics firm, Amstrad.

This company continued to develop the ZX Spectrum but by December 1990 it was all over. Business users had moved onto Windows-based PCs, and gamers favored the likes of the Atari ST and consoles. Production of the old favorite was called to a halt and Sinclair computers passed into history.

A golden legacy
So why should we be recounting the tales of company that had such a brief moment of glory? The hardware wasn’t particularly unique, especially compared to its immediate competitors, although it was cheaper. The ZX81 and ZX Spectrum sold incredibly well in the UK, but significantly less so in other markets.

It is precisely because of these that we still talk about the likes of the ZX Spectrum. Its limitations and large user base gave rise to some of the best known game creators today. British developers, Ultimate Play The Game, achieved critical success on the platform, pathing their way to becoming Rare (makers of Donkey Kong, GoldenEye 007, Banjo-Kazooie, and many other famous games).

Codemasters, purveyors of countless racing games, cut their programming teeth on 8-bit computers — all from the comfort of their bedrooms, after school. And Rockstar North can trace their history back to the mid-1980s, where they were no strangers to the joys of programming a Sinclair machine.

So it should come as no surprise to learn that the ZX Spectrum still lives on, in the form of emulators and numerous fan websites. There’s even been several attempts to hop onto the mini-console nostalgia bandwagon, in the form of crowd-funded projects such as the Spectrum Vega and Next.

But even if you never owned one, or haven’t even heard of it before, the games you play today owe no small debt to the plucky little box. Gone, but absolutely not forgotten.

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