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The ZX Spectrum: A 1-bit wonder

Dr Kenny McAlpine discusses the development and launch of Sinclair's ZX Spectrum, the machine that kick-started the UK games industry.
Welcome back. In this activity we’re going to look at the machine that almost singlehandedly launched the video game market here in the UK – Sinclair’s ZX Spectrum. Well the Atari VCS swept across America, it didn’t make quite the same impact on the other side of the Atlantic. The VCS and other Pong clones like the Grandstand series of television consoles had a solid user base in the UK, but it was the launch of the first home computer kits, towards the end of the 1970s that really captured the British imagination.
The UK has always had a strong hobbyist community, for whom the idea of carefully assembling and soldering the thousands of component parts that made up those early kits, not only posed no problem, but was actively appealing. It was against this backdrop that Science of Cambridge, later to become Sinclair Research Limited launched the microcomputer kit 14, or MK14 in February, 1978, as a minimum cost computer. Now there’s a definite sense of familiarity about the design of the MK14. You can see straight away the influence of Sinclair’s range of pocket calculators on its design, while its conductive rubber keys would later provide the template for the ZX80 and the ZX Spectrum.
The MK14 launched at a price point of £39.95, equivalent to about £200 in 2017 – a real bargain when compared to Commodore’s PET or the Apple II. But, it was a much more primitive machine. Still, it sold well – well enough to justify a successor named the ZX80 for its 3.25 megahertz Zilog Z80 processor, with an added X to denote a magical X-factor. The ZX80 really was a landmark machine. Not only was it the first usable computer to retail at below £100 but it had a built-in keyboard and RF modulator, which meant that it could be connected to a domestic television set for display.
Following the broadcast of The Mighty Micro, a groundbreaking television documentary series about the developing computer revolution, the Further Education Department at the British Broadcasting Corporation began to take a real interest in the home computer market. They established the BBC Computer Literacy Project, a series of television and radio programmes that would be based around a BBC-branded micro-computer. The project was initially scheduled for launch in the autumn of 1981, but that left little time for the BBC to develop its own micro-computer in-house. Instead, they collaborated with the Cambridge-based firm, Newbury Labs to draw up a specification for the machine. The spec matched that of Newbury’s own New Brain micro-computer, the intention being, presumably, that Newbury Labs would pick up the BBC contract.
As the project developed though, it became clear that Newbury labs was not going to be able to produce a machine to spec, and the company didn’t tender. The BBC was forced to postpone the Computer Literacy Project, and broaden their search for a partner. Sinclair pitched the ZX81. Already under development before the ZX80 launched, the ZX81 used a simpler, cheaper chipset, which contained dedicated video circuitry to address the screen fade that affected the ZX80 whenever its processor was busy. A bigger ROM chip, 8 kilobytes to the ZX80’s 4 allowed Sinclair to extend the new machine’s functionality, adding floating point operations and maths functions.
Now Sinclair lost out on the BBC contract to rivals Acorn, who moved into production with the BBC model B, but had negotiated an exclusive contract to supply the ZX81 with the national newsagent chain, WH Smith, who promoted the machine hard. It sold by the thousand. Growing support from the popular press and a burgeoning mail order games marketplace grew the market for the machine, so that when the ZX Spectrum launched the following year, Sinclair had an established user base and an army of independent developers selling through a national network of retail outlets. The Spectrum was the machine that really launched home gaming in the UK, and it’s difficult to overemphasise its importance, both nationally and locally.
It was manufactured at the Timex factory right here in Dundee. And even now, decades later, its recognised as being the touchpaper that ignited the Scottish gaming industry, and led to the degree programmes for which Abertay is celebrated internationally. Free to specify its own components and price point, Sinclair was able to design the most compact and powerful computer that it could, to a price. The Spectrum undercut the 32K BBC model B by over £200 at launch. With the Computer Literacy Project giving the machine free marketing by pushing the very idea of [the] home computer as a tool for learning, thousands of parents bought into the idea, and gave the ZX Spectrum a home.
Even for its time, the ZX Spectrum was a simple machine. Available in two guises, both models had 16 kilobytes of ROM, and either 16 or 48 kilobytes of RAM. It was Sinclair’s first machine to feature any kind of onboard sound interface, albeit a rudimentary one. The introductory booklet that was bundled with the machine claimed, rather optimistically perhaps, that the ZX Spectrum can make sounds of an infinite variety. Most users would have realised pretty quickly that the onboard speaker, which provided just a single channel of playback across a 10 octave range, couldn’t do much except beep. To compound matters, all of the sound commands were managed directly by the Spectrum’s processor, a Zilog ZX80 A.
And so driving the speaker tied up the machine, meaning that while it was beeping, the Spectrum couldn’t, without some very clever machine code programming, do very much else. Little wonder then that few of those early Spectrum titles featured very much in the way of sound at all. Football Manager, one of the first big commercial successes on the platform is typical of the period. Originally developed as a text-only game for the Tandy TRS80, it was ported to the Spectrum to make use of its colour graphics and sound. Simple isometric block graphics are used to display cutscene match highlights, punctuated by rudimentary sound effects at key points in the action.
Football Manager was written entirely in Spectrum BASIC, Sinclair’s version of which came preloaded into the machine’s ROM. Spectrum BASIC provides a single opcode, BEEP, which takes two arguments, a duration expressed in seconds and a relative pitch measured in semitones or fractions of semitones from middle C. Provided you had a passable sense of pitch and the patience to string together a sequence of BEEPs, Spectrum basic provided a very straightforward way to control the sound hardware. And it was how an awful lot of musicians, myself included, tried their first tentative steps into the complex waters of computer music.
The sound on the Spectrum– actually, in truth, almost everything on the Spectrum was limited. And because it was an interpreted language, meaning that programs were decoded and executed a line at a time, Spectrum basic was agonisingly slow. To do anything interesting on the Spectrum required some clever machine code programming and a very creative approach to problem-solving. In hindsight, it might seem odd that the Spectrum became such a success as a games platform. That happened in spite of its lack of built-in joystick ports, its primitive sound, and at times psychedelic colour bleed on the graphics.
I think that, in the end, those were perhaps the Spectrum’s greatest assets, because those hardware limitations forced game developers to find novel solutions and workarounds, and perhaps most importantly of all, focused their attention on creating games that brimmed over with compelling gameplay. Now that’s the idea that I’d like to explore in the next course discussion. The UK games market was a very different one from that in the US. It was much more of a cottage industry, with small enthusiast-run companies, serving the needs of enthusiast consumers. Why did the US and the UK markets evolve so differently? Please spend a bit of time investigating this, and post a response on the discussion board.
I’ll see you again shortly for the next activity.

The ZX Spectrum, even for its time was a simple machine, and yet it almost single-handedly kick-started the UK games industry.

In this video, we’ll look at the launch of the Spectrum and the challenges that its design presented to game developers.

Once you’ve completed the video step, I’d like you to think, not just about the Spectrum, but the gaming industry as a whole.

The emerging UK games market in the early 1980s was a very different one from that in the US. It was much more of a cottage industry, with small enthusiast-run companies, serving the needs of enthusiast consumers. Why did the US and the UK markets evolve so differently?

Below, you can find some links to information and articles about this topic. Please spend a bit of time investigating, and post a response to the comments section.

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