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Sinclair’s 1984 big shot at business: The QL is 30 years old

Quantum Leap micro leapt too early

The Power of One Infographic

Archaeologic In May 1983, Sinclair Research Managing Director Nigel Searle began briefing the press about the successful British micro maker’s next big release. It was 13 months after the company had launched the Spectrum and although that machine had become a huge success, punters and market-watchers were keen to hear about what Sinclair was planning for an encore.

Searle revealed the follow-up to the Spectrum would début early the following year, a date emphasised by the codename he gave: ZX83. The new machine might share the same naming scheme as the ZX80 and the ZX81, but it would be no enthusiast’s micro: set to retail for around £1,000, it would be a business machine. However, it was not an IBM PC clone - Searle said it would run a new operating system of Sinclair’s devising.

A dangerous ploy, some would have thought, avoiding both the slowly fading de facto standard business micro operating system, Digital Research’s CP/M, and its upstart rival, Microsoft’s MS-DOS. Lest potential buyers be put off by Sinclair’s desire to force buyers along its own, third way, Searle teased them with the notion that the ZX83 might even be portable, sport an integrated display based on Sinclair’s flat-screen TV technology and feature solid-state storage.

Sinclair micros

The Sinclair Research family: the ZX81, the Spectrum and (front) the ZX83 - aka the QL.
Source: Marcin Wichary

The machine Searle was busy dropping hints about would eventually be released as the QL - short for "Quantum Leap" - and it would indeed be launched early in 1984, on 12 January at the Inter-Continental Hotel on London’s Hyde Park Corner. Many more months would pass before the new Sinclair micro arrived in buyers’ hands, however, prompting wags to dub it the "Quite Late".

But it would not be a mobile machine. Nor would it have a built-in screen, or on-board solid-state storage. It would jump out of the 8-bit world of the Spectrum and its rivals, and into the 16-bit domain. It would also wave farewell to chip designer Zilog, creator of the ZX machines’ Z80 CPU, in favour of Motorola and its 68000 family. Out went Sinclair’s trademark single-touch Basic keyword entry too.

In charge of creating the QL was David Karlin, a young engineer in his early twenties who had just returned to the UK from a stint in Singapore with the Fairchild Camera and Instrument Corporation, where he’d been engineering digital signal processor chips. Back in Blighty – not entirely a move of his own choosing as it was his wife of the time who wanted to return - Karlin approached a recruitment consultant about a possible job opportunity he’d seen advertised. The advisor said the post wasn’t right for him and suggested instead a vacancy that had just come up at Sinclair Research. A meeting with Clive Sinclair later and Karlin was hired as Chief Design Engineer, Computers.

David was one of a number of bright sparks Sinclair Research brought on board on the back of rocketing Spectrum sales. Karlin wasn’t particularly keen to return to Cambridge, where he’d taken his degree and MA – in Engineering and Electrical Sciences – but Sinclair was willing to pay him the salary he’d been making at Fairchild, well in excess of what he might otherwise earn in the UK, so he couldn’t really say no.

Star hire, Star plan

Besides, he had a computer he desperately wanted to build. His time at Fairchild had begun with a brief induction period at the company’s Palo Alto HQ. There he’d encountered a Xerox Star, the colossally expensive workstation that introduced the WIMP (Windows, Icons, Menus and Pointer) user interface and which - unknown to him at the time - inspired Steve Jobs and Apple to build the Lisa then the Mac, and Microsoft’s Bill Gates to start work on Windows. David was enthralled, and like Jobs and Gates realised that here lay, in concept, the future of personal computing.

His notion, then, was to “create a £500 Xerox Star”, and it was this vision that helped persuade Clive Sinclair to give him a job. It also helped that Sinclair Research desperately needed to devise a business micro for recently denationalised UK IT giant ICL.

In May 1981, Robb Wilmot joined ICL as its new MD. He was just 36 years old, and in his previous role he had been Texas Instruments’ youngest vice-president, in charge of the UK calculator division. He was also pals with Clive Sinclair. Wilmot believed that Sinclair technology could enliven ICL’s desktop computing range; ICL’s Dataskill subsidiary was already offering programs for the ZX81 and had been making business-centric software for home micros since the Nascom 1 days. Sinclair and Wilmott cut a deal, announced to the public some month later, in December 1981.

First, ICL would license Sinclair’s version of Basic, a move likely suggested by Sinclair in response to the BBC’s decision to adopt Acorn technology for the BBC Micro. It had always been Sinclair’s line that the BBC should have partnered with him because he, not Acorn, had the closest thing there was to a standard dialect of the language – ICL’s support for Sinclair Basic would cock a snook at those Corporation fools.

Rick Dickinson 1981 pre-QL sketches

Two of Rick Dickinson’s 1981 pre-QL sketches. Around this time, ICL asked Sinclair Research to create it a business micro.
Click for a larger image. Source: Rick Dickinson

Second, ICL said it would also buy Sinclair flat-screen TVs for a combined desktop computer-cum-communications terminal it had a mind to offer. Sinclair would develop the machine’s underlying hardware. In return, Sinclair gained £1m up front to help finance development costs. It also received a commitment from ICL to pay it royalties when the product shipped.

Sinclair Research’s industrial designer, Rick Dickinson, still has a series of concept drawings dated to between May and August 1981 which show various wedge-shaped machines equipped with a pair of Microdrives, the tape-based storage system in development at Sinclair, and what appears to be a small, integrated display. Some sketches also feature a built-in printer. The angular look presented in Rick’s pictures is not a million miles away - phone handset notwithstanding - from how ICL’s One-Per-Desk (OPD) eventually appeared.

There were many other ideas for future machines being kicked around at Sinclair too. Today, David Karlin recalls talk of an advanced, second-generation Spectrum that could also be used by business and educational establishments. He believes that’s what Clive Sinclair had in mind when he outlined his vision of a £500 Xerox Star. The Sinclair chief always had an eye on the business market, even at one point trying to suggest the ZX81 was a business micro.

Despite their apparent similarity to the OPD, Rick Dickinson’s sketches may also reflect general thinking within Sinclair Research about its post-Spectrum products. These concepts may even have persuaded Robb Wilmot to ally ICL with the company in the first place, and influenced the parallel evolution of the OPD look. Thirty years on, memories are too hazy to be certain. But then Sinclair Research never went in for formal development processes, or for consensus views on what a future machine would do and for what audience.

Planning the ZX83

Rick’s early design work was done more than a year before Karlin joined Sinclair, and while work was proceeding on the Spectrum itself. The ZX81 had only just been launched at that point. Karlin arrived in the late summer of 1982 and immediately began putting together a preliminary specification for his business machine.

He envisaged a desktop computer that would feature a proper keyboard and “some kind of networking”. It would come supplied with a dedicated monitor and its own printer, “both of which I considered to be really the minimum for a decent business machine”, he recalls. “In fact, in terms of broad spec, you could say I was trying to design what the Amstrad PCW 8256 would eventually become.”

He also wanted some kind of windowed user interface, which would in turn require high-resolution bitmapped graphics, plenty of memory and a fast processor. Intriguingly, though, he did not plan to add a mouse. “That seems an odd choice now, but at the time, I was fairly confident that people could do enough with arrow keys,” he says.

The early design work centred on the silicon. “I asked myself, how can I get high-resolution video, which was clearly needed, in a way that isn’t going to cost money. Costing money essentially meant costing pin counts. That was the critical issue at the time. When you built a custom IC, if you went into anything above a 40-pin dual in-line package, the cost skyrocketed. So as far as I was concerned I was limited to 40 pins, which mean a hell of a lot of gate-count arithmetic and pin-count arithmetic.

David Karlin - then and now

David Karlin, then (1982) and now

“The design style in Clive’s shop was, if it costs ten pence and we can get rid of it, then let’s get rid of it; if it costs a pound and we can get it down to 90 pence, then we’ll do that, and if we can get it down to 50 pence that’s better still. Literally, you were counting the cost of capacitors and the design process was all about getting every last inch of cost.

“In a sense my game was: I know the base minimum functionality I want, I know the cost constraints that Clive wants, so can I make my stuff fit into that constraint? And that was pretty much the design process.”

Since the ageing Z80A microprocessor could only address 64KB, and Karlin was adamant that paging blocks of memory in and out would hinder performance, he also decided that his machine needed a 16-bit processor. He considered Zilog’s Z8000 and Intel’s 8086, but quickly rejected both in favour of what was, for him, a much better option: Motorola’s 68000 series.

“It was clear the Z80 was going to have two big problems,” he says. “Firstly, it just not being fast enough and, secondly, not having the addressable memory space. The idea of faffing about doing our own hardware paging, which was the only option when you only had a 64KB address space, did not appeal.”

New era, new processor

Neither did the 68000 itself, but for a different reason. Instead, Karlin chose the 68008, running at 7.5MHz - twice the frequency of the Spectrum’s Z80A. The 68008 was built for backwards compatibility, so it featured an external 8-bit data bus and 20-bit addressing. The 68000, as used in the first Mac, the Amiga and the Atari ST had a 16-bit data bus and 24-bit addressing. Both Motorola chips could handle 32-bit word lengths internally.

“I don’t know how robust the decision was,” David admits now, “but it seemed fairly clear that the the 68000 series would be a great platform for the future - it was a very, very good processor. The problem with the 68000 was basically a pin-count issue. Motorola was pricing it gigantically higher than the 68008, double or treble the price. It was sufficiently high I didn’t even argue about it.”

Rivals’ use of the full 68000 would later come as something of a surprise. If Sinclair couldn’t afford the 68000, how could they? Today, David blames Sinclair’s negotiating skills, not just for the CPU but for a whole variety of logic chips and add-ons: “I question how good we were at purchasing, because people like Amstrad, certainly the Japanese, certainly Apple, who did not have gigantically higher volumes than us at the time, got massively lower prices.”

Based on Karlin’s recommendation, Clive Sinclair approved of the use of the 68008 in December 1982, formally pegging the company’s future on the platform. During 1983, it has been claimed, Motorola cut the price of the 68000 to below what Sinclair had agreed to pay for the 68008. Renegotiating the purchase contract might not have been costly, but adding in the architecture the full 68000 chip required - extra banks of Rom and Ram, a separate system logic chip, would have been, so it was decided to stick with the 68008.

Clive Sinclair and Robb Wilmot

Pre-QL players: Clive Sinclair (left) and ICL’s Robb Wilmot

Ironically, given the way the ZX83 hardware evolved through its development, it’s easy to say Sinclair would have well been better off going with the 68000 after all, but only with the benefit of hindsight.

Karlin decided that just two custom chips would operate alongside the CPU. The first, the ZX8301, would connect the 68008 to the rest of the system. It would operate as the processor’s clock, manage the memory timing, and mediate CPU and display controller access to Ram. It would also control the display through a dedicated link.

The second ULA, the ZX8302, would handle the IO, including the Microdrives, the network and a printer port. It would integrate a modem - mandated by ICL’s requirements for the OPD - plus the ZX83’s planned battery backed real-time clock and the keyboard interface. Apart from Ram - then imagined to be 64KB split 50:50 between program space and video memory - and Rom chips, that’s all the ZX83 would need, it seemed.

Naturally, it never quite worked out that way.

Work begins... but on what?

At the start of 1983, with the basic system logic outlined and a CPU selected, Karlin started to devise the machine that would be based on these components and to specify the core software that would be required. In March 1983, he was given a nine-month deadline to deliver the ZX83. This would allow the machine to be launched just before Christmas.

Even then it seemed, to some, a crazy deadline: Sinclair hadn’t yet succeeded in creating a machine in such a short timeframe, and this was no extension of a well-understood, established platform. Sinclair’s chief hardware engineer, Jim Westwood, appears to have been a lone senior management voice arguing that more development time was necessary, but his advice was effectively ignored.

The short development period would be tough enough for a new desktop machine, but it seems doubly arduous if Sinclair was indeed intending that the ZX83 be a portable computer, as Nigel Searle’s May 1983 comments to the press suggest. David Karlin says that the notion of creating a portable machine didn’t come until much later, but his chief software goal toward which ZX83 development initially proceeded during the first few months of 1983.

Sinclair bosses clearly did want to offer a portable, particularly following the May 1981 introduction of the Osborne 1. It’s very telling that the sketches made by designer Rick Dickinson around that time feature a machine with a small display, two removable storage drives and an integrated keyboard - the very defining features of the Osborne 1, though it’s impossible to say from the drawings whether they represent a portable or a desktop.

QL Schematic

Post-launch QL schematic
Click for larger image

In April or May 1982, Clive Sinclair when questioned about what was then the ZX83, said: “The next step will be to make a machine of a suitably higher price [than the just-launched Spectrum] which would have a built-in screen and dual floppies - Microdrives, that is. It is conventional in the sense that it contains what the Osborne or the IBM personal computer have, because that is what is needed.

“We have three elements that people will want: our printer, the flat-screen display, which is critical - the world needs flat screens, that technology is paramount - and the microfloppy, and you bring them all together. That package becomes a much handier package than, say, an IBM system.

“We are doing something that is maybe a couple of pounds in weight - say two to four to be on the safe side.”

Was the ZX83 intended to be a portable, despite David Karlin’s desire to build a low-cost business desktop? Certainly there are clear parallels between his notion of a highly integrated system, and a portable design with integrated screen, printer and modem. A portable computer was clearly a topic of discussion at Sinclair long before Karlin came aboard, and would continue to be a feature of the company’s roadmap, such as it was, ultimately finding physical form in 1985’s ill-fated Pandora project. This bizarre machine, complete with a Sinclair micro-display, was killed when Amstrad took over, but it eventually led to Clive Sinclair’s Z88 portable.

Most likely, the portable was always Sinclair’s ‘next-but-one’ micro. Some seem to have certainly experimented with the idea: Tony Tebby remembers an Sinclair micro-display being hooked up to a Spectrum and the barely legible results prompting him to add proportionally spaced fonts to an early draft of the ZX83 OS as this might allow the display to present readable text.

One suggestion that the portable be powered by batteries produced for the Sinclair Microvision 2700 pocket TV was very quickly dismissed when calculations showed they would support just 30 minutes of operation, falling to a mere 10 minutes if the Microdrives were running.

If there was any serious plan in place to build a portable, it was wrecked by these findings. But such was the nebulous nature of the ZX83 project, with all participants seeming to have subtly and not-to-subtly different ideas about the machine they were building of having built for them, that at this remove it’s very difficult to tease out the "true" specification. One engineer’s research effort was another’s provisional spec.

Suffice it to say, certainly by the summer of 1983 but more likely rather sooner, anyone hoping that the ZX83 might be a portable computer was now sure it would not be. The lead times required for designing, sculpting and engineering the case were such that, to ensure a late 1983 launch, the machine’s form-factor would have to have been set in stone by the middle of the year.

Planning the software

While David Karlin was sorting out the hardware during the early part of 1983, Tony Tebby and new recruit Jan Jones were working on the computer’s core software: the operating system and its Basic interpreter.

An Oxford physics graduate specialising in nuclear and solid-state physics, Tebby originally set out working for GEC on microwave systems. His work exposed him to the protean computer-aided design software of the time, which he found crude and unsuitable. So he learned programming “at night school” in order to try and produce something better himself.

This led him to a career shift: into CAD coding, which took him first to Philips and, later, to a joint venture between ICL Dataskill and the Department of Trade and Industry: CAD Centre in Cambridge, which he joined in 1979. It was there he met Jan Jones, who had become a programmer straight out of Sixth Form. She studied for a Maths degree part-time while working at British Gas and, later, the Royal School of Mines. Then she joined CAD.

In 1982, Tebby was hired by Sinclair Research as software engineer, part of the company’s same grab for talent that brought David Karlin into the fold. It was Tebby who invited Jones to come and join him at Sinclair, to work on SuperBasic, a version of Sinclair Basic to be brought up to date with the addition of some of the structured programming features that had been built into BBC Basic. Jan remembers coding it all up in 68000 assembly language after a long specification process in which the language’s commands and features were mapped out.

QL Screens: startup and Basic

QDOS start up and the three-window monitor-oriented SuperBasic UI. In TV mode, the top two windows were overlaid

David Karlin insists he always intended to build the language into the machine, not only for application programming and to allow third-party applications to be run, but also as the ZX83’s “elegant, easy to use, nice and fully featured” shell language.

Tony Tebby, on the other hand, recalls bringing Jan Jones on board when Sinclair bosses decided that the core ZX83 hardware might also form the basis for a future incarnation of the Spectrum.

Karlin also says it was always his intention to use Tebby’s QDOS operating system, called "Domesdos" during development, and that the software engineer’s work on it was not a "spare time" project as has been suggested. For that reason, it was once claimed - and the claim has continued to be repeated by others ever since - that QDOS was a last-minute substitution, dropped in when it became clear an OS being developed by an outside contractor, GST Computer Systems, would not be ready on time.

No so, says Karlin: “That’s the wrong way round.” GST was the insurance policy taken out by Sinclair management, he says. The thinking went: “If this his little in-house team we don’t know and don’t necessarily entirely trust don’t deliver, we’d better have an operating system up our sleeve, so GST got commissioned to do that.”

Playing it safe

Tony Tebby’s recollection is different. He says he commissioned GST, initially with no formal approval from Sinclair management, to create an operating system for the new machine. “I was brought in to find, not necessarily to write, the QL’s operating system,” he remembers. He started to author one anyway, though, just in case.

But he once wrote, “I would never have been able to take the technological risks that I did if I had not been confident that, however badly I screwed up, GST would produce the world’s best multitasking workstation OS on time”, which seems a tacit admission that GST was indeed the back-up.

Tony says he also tried to interest Digital Research and Microsoft in the job: DR simply wasn’t interested, and Microsoft said Tebby’s conception of what the new OS would be capable could not be realised on the hardware of the time.

Today, he chuckles at the famous firm’s seeming inability to do what both GST and he were, separately, able to achieve. David Karlin says Tebby’s work, with its incorporation of, for the time, advanced features such as multi-tasking, was far ahead of anything Microsoft would have been able to come up with.

QL Screens: Abacus

Psion’s Abacus spreadsheet application

How was Domesdos selected in place of GST’s work? Tony Tebby says his operating system and GST’s were put “head to head” at a meeting held in November 1983, though he admits he was not present. The result of this review, however, was that GST’s OS was out and his was in. Why? Most likely because, being an in-house job, Domesdos could more quickly be updated once the still-unfinished hardware became available. GST later released their work under the name 68K/OS.

“Conceivably, different people had different impressions of what was on,” says Karlin. “It’s completely possible that so far as Nigel Searle was concerned, Tony’s work was being done to keep me happy and the intention was to use GST and when that didn’t happen, we carried on with QDOS. That was not my impression, but that’s not to say you didn’t have different camps of people thinking different things.

“As far as I was concerned, the stuff Tony was doing was what was going to be used and that the GST stuff was there as a back-up in case we were unable to make QDOS work, but we were able to make it work.”

Separately, Psion software, which would go on to create the Symbian mobile operating system, was hired early in 1983 to produce a set of productivity applications which could be bundled with the new machine. Psion had been approached by Nigel Searle during December 1982, as had a number of other software houses with a view to sounding them out as potential supporters of the new micro. David Karlin says that including applications was always part of the plan, though he was not involved in choosing Psion. Neither was Tony Tebby, it seems: GST has a suite of its own in the works alongside its work on the OS.

Applications, applications, applications

Quite possibly Psion’s very ambitious Managing Director, David Potter, cut a deal early on to ensure Sinclair funded the development of Psion business applications which would be initially released on the ZX83 but could later be released on other platforms. Alun Sugar, in his autobiography, calls Potter and co. “an arrogant bunch of tossers”. Tebby claims the company as conveniently already working on MS-DOS applications which it could re-purpose for the QL deal. He cites a late-in-the-day request that the QL should support the 80 x 25 textual display for which the apps had been written, though this could easily have arisen because, with no ZX83 hardware, Psion had had to guess the machine would use this then common screen format.

Potter, like many others in the micro business at that time, realised that the market for business computing was about to grow the way the home computing market had been, and wanted to get a foot in the door. The ZX83 project would certainly have allowed Psion to do so with much less risk than launching standalone applications would. If the ZX83 sold as well to business as the Spectrum had to teenagers, it would establish Psion’s Quill word processor, Easel graphics tool, Archive database and Abacus spreadsheet – together later called the xChange suite - as a new de facto standard in 16-bit business applications.

“We had long discussions with Sinclair,” Potter said in 1984. “Psion is an ambitious company... We wanted... to be producing the fundamental software tools - the word processors and spreadsheets - a market dominated by the big US software companies.”

Psion devoted almost all of its coding resources to the ZX83 applications. “It has been a huge effort for us,” said Potter. “Frankly, this is why we haven’t been coming out with too many home computer products recently.”

QL Psion xChange

Psion’s Microdrive suite
Source: Rama

Each of the four applications were put in the hands of their own team leader. Martin Brown was in charge of Easel development; Martin Stamp oversaw the Quill team; Charles Davies ran Archive development; and Abacus’ was Colly Myers’ baby. Myers went on to become Psion’s MD and, later, CEO of Symbian.

Psion’s programmers would spend the next 15 months completing Quill, Easel, Abacus and Archive. With only a very basic idea about how the ZX83 would operate, they coded the applications on the company’s Vax minicomputer running a 68008 emulator until the ZX83 and QDOS were complete.

But toward the end of 1983 neither were. The very fluid concept of what the kind of micro the ZX83, and Sinclair management’s refusal to extend the development deadline, were to blame. Deciding that the business-centric ZX83 platform might form the basis of future Spectrum home computers didn’t just mandate a new, 68008-based version of Sinclair Basic, it also meant that David Karlin’s initial specification for the machine’s two ULA chips had to be revised.

For instance, the ZX8301’s display controller circuitry would need to be altered to provide support for existing Spectrum display modes. The ZX8302 would now require a slick sound generator, to allow the machine to produce rather better sounds and music than the Spectrum could.

Separately, it was decided it would take too long to build a modem into the ULA so it was dropped, along with with output-only printer port, to be replaced by two generic RS232 ports.

Shifting specifications, fixed deadline

Getting all the extra functionality in under the constraint imposed by the chips’ ‘40 pins maximum’ limit proved almost impossible - the serial IO now required eight pins not four, for instance - and this appears to be the main reason why plans for a ZX83-based Spectrum were quietly shelved late August or early September 1983. With the ZX8302 still unfinished and “running out of pins”, as Tony Tebby puts it, it became necessary to offload the keyboard interface.

Enter one the ZX83’s more controversial design decisions: the use of an Intel 8049 microprocessor in the system logic. It was dubbed the “Intelligent Peripherals Controller”, something of a misnomer. David Karlin put it to work handling the keyboard input. “Again it was all pin-count driven,” he explains. “To be able to do the keyboard we needed something with lots of pins to drive all these keyboard lines. So we asked, what’s the cheapest thing we can find that has lots of pins? It turns out that it’s not a few bits of TTL you drive directly off the main processor, it was actually cheaper to have a second processor.”

Especially since the 8049 would have capacity left over to deliver the sound generation and to free the ZX8302 from having to handle the serial ports. There were downsides: Karlin originally envisaged the ZX8302 providing a centralised bank of interrupt and status registers for peripherals, a smart scheme for reducing hardware costs and simplifying the software. Adding the 8049 meant this was no longer possible - the 8049 had to use its own status registers.

Tony Tebby handed the task of interfacing the 8049 into QDOS to a new assistant, Aaron Turner. It was a tough job, but Turner managed it. It was much, much harder getting the 8049 and its lines onto the long, narrow PCB mandated by case, which had been agreed at a point when the specification was such that everything would fit.

Inside the QL

Inside the QL. This modified machine features a new Rom and IPC. Click for a larger version.
Source: Ewx

The PCB size problem was compounded by a relatively late move to make the ZX83 itself more friendly to home users: it would now have to have TV output and joystick ports, odd additions for a business micro. The joysticks could be added with a pair of ports and a few lines running off the 8049, but adding a UHF modulator was a major headache. It could only be fit in right next to the Microdrives – with their frail read/write heads, this was the last place you’d want to put a source of oscillator noise.

And if the ZX83 was to appeal to home users, it would also need a Basic. Jan Jones was hard at work on SuperBasic, which would fit the bill. The trouble was, SuperBasic was not only scheduled separately - designed for a post-ZX83 Spectrum-brand product, it was months away from readiness - but it had not been designed to run on top of QDOS. Instead, it was a classic ‘boot into Basic’ operating system in its own right, says Tebby, as per the Spectrum and almost every other 8-bit micro.

Adapting SuperBasic’s graphics routines – then under development at GST in a bid to bring the release forward – to operate through QDOS’ display manager rather than write direct to the video Ram was relatively straightforward. Aaron Turner was given the job. Rewriting the interpreter to obtain or release memory through QDOS’ memory manager rather than do so itself was a much more involved task.

And one that would have taken too long if Tebby and Jones were to meet the pre-Christmas launch schedule. With just four weeks to go, much of which had to be reserved for testing the code with hardware, Tebby elected to hack QDOS and SuperBasic to allow the interpreter to run as a special, one-of-a-kind privileged task. It was, he says, “a terrible mistake [that] compromised the OS’ integrity”.

A tale of two Basics

At this stage, it seems to have been still the plan to deliver two versions of SuperBasic: a compact, minimal version in the ZX83’s Rom, and an extended version which comprised the full language but would come later, on Microdrive tape or on a plug-in Rom cartridge. The minimal SuperBasic would check for the presence of Extended at start-up and load the extensions accordingly. This would, says Tebby, allow the ZX83 to ship with Basic and still give the coders time to finish the full package.

Not that any of the hardware concept changes - from portable to desktop, from ‘Super Spectrum’ platform to an ‘Spectrum plus’ in its own right - had warranted any extension of the development team’s deadline, at least not as far as Sinclair management were concerned.

The only formal set-back to the timetable was to schedule the launch the machine early the following year rather than before Christmas. David Karlin and Jan Jones both say the machine’s development was then at a stage where it needed at least six more months’ work, a duration defined, in part, by the then long turnaround times involved in producing PCB and ULA samples. According to Tebby, they didn’t even have a working prototype at that point, almost entirely thanks to the many changes that needed to be made.

Karlin would surely have made Nigel Searle and Clive Sinclair aware of this, but nonetheless the decision to introduce the machine to the press in January 1984 was upheld. This annoyed Tebby, but the claim made at the launch that the first machines would be in buyers’ hands within 28 days of their orders being received was the final straw: knowing this deadline could not possibly be met, he handed in his notice and said he would leave Sinclair when there was a machine in production.

QL launch: Micro Men style

Launch re-imagined: the QL’s debut from Micro Men with Derek Riddell as Nigel Searle and Alexander Armstrong as Clive Sinclair
Source: Darlow-Smithson/BBC

He duly left Sinclair’s employ at the end of April, though he was set up in an temporary office round the corner, he says, where he could be called upon should his assistance be required. He refuses to name the Sinclair Research director who arranged this.

The launch had another effect: the inevitable Sinclair miscommunication ensured that the company’s marketing team knew only that the QL, as the computer was now called, would come with a Spectrum-friendly Basic, not what it could and couldn’t do, or that there would be a two-stage release. They assumed they could fill out the pre-release documentation for the press with information from the Spectrum manual. But they didn’t check it with the developers. The upshot was that, having told the world the QL would ship with what was effectively the full version of SuperBasic, the company would now have to supply it.

At the launch, Searle promised Sinclair would begin taking orders for the QL at the end of January. The computer would ship with 128KB of Ram, and be priced at £399 plus £7.95 postage and packing. There was no mention of the 64KB version, originally intended to go on sale for £299, because Psion’s applications would need more than 32KB of memory. The machine would make is retail debut the following Autumn, Searle said, when it would also go on sale in the US for $499.

Of course, Sinclair hadn’t managed to get its previous computer, the Spectrum out on time, and the Microdrives took even longer to arrive: they were more than a year late. A few observers rightly guessed it wouldn’t do so this time round either. But such fears didn’t stop many thousands of punters - more than 9000 by the end of February, rising to 13,000 as of late April - sending off their credit card details or their cheques, which the company had no hesitation in cashing.

Top three mobile application threats

Next page: Delay after delay

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Uncle Larry's mutually-optimised stack to become clearer in August
EU dons gloves, pokes Google's deals with Android mobe makers
El Reg cops a squint at investigatory letters
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