BBC Micro – The computer that helped build an industry
The BBC Micro educated scores of future games programmers and helped spark a computer revolution
Today, having a computer in the house is largely taken for granted. Most of us have a laptop or desktop PC or Mac and children don’t generally have to plead and beg their parents to buy them one. Not so back in the eighties. At that time, computers were still the shiny sheriffs of gadget town and kids typically had to use all of their cunning and might to persuade the powers that be in their household to get the chequebook out at the local computer store.
In a lot of cases, there was a simple utterance which seemed to do the trick: “Pleeeaaaase,” the young voices would say. “I really need one to help with my school work and I’ll be left behind in class if I don’t get one.” Yet some households remained sceptical. Those who didn’t see the benefit of owning a computer figured those young minds weren’t entirely interested in the more serious applications of computing and only really wanted something to play games on.
But then a machine arrived that would add much weight to the argument of Britain’s youth: one that bore the name of the world’s most respected broadcaster. When the BBC Micro was launched, suddenly computers had a veneer of respectability and parents became turned on to the prospect of computers and their ability to give their kids a leg up at school. In truth, it served in many cases to simply acquaint children with the delights of Chuckie Egg but there was no going back then.
The BBC Micro was arguably the most important computer ever to be launched in the UK. Released on 1 December 1981, it was bought by schools up and down the country and it helped to kickstart a revolution. Scores of future games programmers honed their craft on the computer, from David Braben and Ian Bell who debuted Elite on the BBC Micro to Philip and Andrew Oliver who produced Repton for Superior Software. It led to numerous gaming exclusives including the side-scroller Strykers Run, Magic Mushrooms, Beyond Infinity – Cute To Kill, Galaforce and the Asteroids clone Camouflage.
Without it, the early days of games programming would have been so much poorer. In fact, who is to say how well some of the industry’s earlier computers would have fared if the BBC Micro had never existed? There is an argument that the ZX Spectrum and the Commodore 64 wouldn’t have proven as popular on UK shores had the BBC Micro not engrained itself so well into the public conscious. Those who couldn’t stump up the cost of the Beeb’s machine invariably sought those less expensive alternatives.
But why did the BBC decide to go out on a limb and enter this fledgling industry? “The broadcaster wanted a BBC-branded machine to base the television programmes around,” begins Steve Furber, who joined Acorn Computers as a hardware designer in 1980.
The BBC Micro was indeed created to serve a very specific purpose: to complement the Beeb’s Computer Literacy Project which not only sought to make the British public aware of microcomputers but teach children how to use them. The idea was to launch a book, a range of applications, a course in BASIC coding and, crucially, a ten-part BBC series called The Computer Programme, which it hoped to have on air in January 1982. The problem was, it was early 1981 and the BBC knew there wasn’t enough time to make a computer all by itself. So those behind the project decided to challenge British computer manufacturers to come up with something suitable for them instead.
At the time, Acorn had been working on a computer called the Proton. Intended as the superior successor to Acorn’s hugely successful Atom, it ended up being based on a design Furber had created during his PhD at Emmanuel College, Cambridge. “My earliest memory was sketching the very rough Proton circuit diagram around October 1980,” he says. Furber hadn’t progressed much further by the time Hermann Hauser and Steve Curry, who founded Acorn in December 1978, got wind of the BBC’s plan.
Hauser spoke to the BBC to put his company forward as a contender to design and make the Beeb’s new machine, even though he knew the Proton only existed in name as a dual-processor concept. His persuasive nature saw Acorn placed on the BBC’s shortlist and arrangement’s were made to visit the computer firm’s Cambridge HQ that Friday. It was then that Hauser felt he had better let his team know what was going on. “He rang myself and [fellow engineer] Sophie Wilson to ask if we could have a processor available by the Friday,” says Furber. “We both said ‘no’ but he told us both that the other had said ‘yes’.”
Fooled into getting a computer ready in just one week, the team got down to work. They decided to base it on the Proton, even though they only had their initial sketch and a draft specification from Hauser to go off. The Proton was to have a dual processor: that is, two 8-bit processors working together. It was also intended to have graphics and sound that would be good enough to head off any potential competition from Sinclair. “We filled out the details on what had been the Proton schematic on the Monday,” says Furber. The BBC Micro was about to be born.
Building the Beeb
Furber enjoyed creating computers and he did it for fun. “I’d say hobby, but I was in aerodynamics and, as a PhD student, I was using the machines I built to write my thesis,” he says. This, however, was something else. Not only was the development supposed to be completed in rapid time but the stakes had something of a personal flavour too because Curry and Hauser had worked at Sinclair Research and they wanted to prove they could beat their former employer. The two companies also saw the BBC’s project as a big deal, since it not only offered great marketing potential but granted huge prestige for the winner.
Surprisingly, though, education wasn’t first and foremost in Furber and Wilson’s mind when they were creating the computer, despite the remit handed to them by the BBC. “The Acorn ideology was to build computers that we liked and then hope that customers would like them too so there was little educational ideology at the start for us,” Furber says. Instead, they looked to create a prototype that would simply impress, not knowing what the competition was up to (we ask Furber if the team knew what Sinclair was planning? “No,” he answers, firmly). Hauser was confident from the very beginning that they would pull it off.
But then he had assembled a talented team. Wilson, another Cambridge graduate, had been heavily involved in the Cambridge Microprocessor Society as a student. She had designed an electronic cow feeder for a farmer in Harrogate and she became a respected consultant. It was her work that had led to the production of the Acorn System one 8-bit computer that had morphed into the Atom. Producing a computer in a week, though, was something else. The team knew they had to get some outside help.
On the Tuesday, Ramanuj Banerjee from the Cambridge University Computer Lab was invited to join, his task being to wire up the prototype. This took him until the following day. “We called him the ‘fastest wire-wrap gun in the West’,” Furber jokes. Once that was complete, the team was able to debug the machine to make it work and they toiled until the Thursday evening, their intense mission to get the computing working properly leading to mild panic when it kept throwing up a fault.
It turned out to be easy enough to resolve. Hauser suggested the in-circuit emulator cable be cut and to everyone’s surprise, it did the trick. By 7am on the Friday, the team was satisfied with their prototype and it was ready to be shown to the BBC team at 10am. As they arrived, they were taken to Curry’s office for a talk before being allowed to see the prototype in all of its glory. They were very much taken aback.
To ensure the machine looked its best, Acorn had asked for a case to be made. “The casing was designed by Alan Boothroyd,” Furber says. This was important because Acorn wanted to display the product in as complete a state as possible so that the BBC could get a better feel for it. Boothroyd looked to make the computer stand out so he created some red keyboard buttons. It was an eye-catching touch. “Sophie had also spent the week building the programming language, BBC BASIC, with strong inputs from the BBC’s specification,” Furber says.
The language was ready for the BBC crew to see that Friday morning along with some apps. By the afternoon, Wilson had got it to run black and white Mode 0 graphics in a resolution of 640×256. Duly impressed, the BBC promptly awarded Acorn the contract, allowing Hauser and Curry’s company to beat the likes of Sinclair Research, Newbury Laboratories, Tangerine Computer Systems and Dragon Data. Even though the BBC had known all along that Acorn did not have a prototype when it spoke to Curry on the phone, it was impressed by the amount of work completed in such a short space of time. Yet it was only the start. With the agreement in place, the real work would now begin to create a fully fledged computer that would be rolled out to schools and shops a year later.
Acorn worked with the BBC on a final specification for the machine. “There were a lot of discussions about the software, and in particular the spec of BBC BASIC, but less about the hardware,” says Furber. Even so, Acorn convinced the BBC not to go with the Z80 chip and opt for the 6502 instead. A 1Mhz 6502 processor been used in the Atom, and Acorn felt it was the best option. For the BBC Micro, though, a faster version was used.
“We went with a 2MHz 6502 processor and 4MHz main memory multiplexed between processor and graphics,” says Furber. With that nailed down, there was a fair bit of fiddling with what are called Uncommitted Logic Arrays (ULA). These allow a number of logic gates to be configured to implement a bespoke function on a single chip. By using them, the chip count could be lowered, saving money on the computer’s production.
“We’d decided to reduce the number of chips by using the ULA in a couple of functions, a serial processor and a video processor, which took the chip numbers down by 10 or 20,” says Furber. A lot of effort went into cleaning up the schematics too. “We also got the circuit board PCB inside,” he adds. But it wasn’t all about practicalities and expense. “The design didn’t really pull tricks, but we pushed the performance – the 4MHz memory was the first at that speed, and things were a bit close to the edge. We mostly got away with it,” Furber explains. While this work was being carried out, Paul Bond led a team working on the operating system – known as Acorn MOS, which included support for four channel sound and graphics – and the exterior was also being tweaked. The BBC had wanted a set of ten user-programmable keys in addition to a full-Qwerty keyboard and so the team got to work and these were soon added.
Beeb bosses also asked for a default graphics mode based on a Teletext display, which became known as Mode 7, but a few niggles emerged. “The video processor was the most worrying,” Furber says. “It kept overheating.” A large heat sink helped to take care of that but there were other issues that followed.
“The 6502 databus was also pretty horribly overloaded and the early prototypes would only run reliably if we placed one of our fingers across the PCB tracks,” Furber says. “In the production machine, we had a resistor pack to do this job. We never really understood why it helped but it seemed to work.”
Power supply issues also dogged production too. “Initially the BBC insisted on a linear supply but that was never going to go well with the small space in the box and the poor efficiency of linear supplies,” Furber explains. “After a few had caught fire, the BBC eventually relented and we got a switched-mode supply put together very quickly by Aztec in Hong Kong. That fixed the problem permanently.”
The final result was a Model A computer costing £235 with a 6502A processor, 2MHz speed, 16KB RAM – expandable to 32KB – 32K ROM, three channel sound and a tape recorder. Another version – the Model B – was also launched. This one would cost an extra £100 but it had 32KB of RAM, which was expandable to 64K, a 5.25-inch floppy drive and software that could run the disk operating system CP/M. But did it sell? It sure did.
On the shelves
The BBC envisioned selling around 12,000 computers, while Wilson and Furber believed that it was more than good enough to sell around 50,000 computers. Yet even though the price of the BBC Micro was higher than Acorn had wanted – “It was expensive to make, so we had to give it a higher price,” says Furber – it went on to sell 1.5 million units over its lifetime. The computer was able to retain its popularity because of its expandable nature, which ensured that it could be tailored to suit the growing demands of its users.
In that sense, the Micro was an ongoing pioneer that was bringing fresh ideas to the table all the time, such as a Motorola 68B54 networking controller that enabled multiple Micros to be linked together. “The Econet local area network was prototyped on the Atom and it was an obvious inclusion on the BBC Micro, even though the rest of the market hadn’t heard of networks at that time,” Furber explains.
By March 1983, BBC Micro User magazine was reporting sales across Europe, with production hitting 11,000 a month. There was a major sales drive in the USA too, although the primary market was always the UK, with the States having taken to the Apple II in far greater numbers (Apple II was released in 1977, giving it a time advantage).
“There was a lot to be said for the BBC Micro,” says Furber. “There were the technical things: the expandability, the native performance, BBC BASIC, the hammering that the keyboard could withstand without complaint. But there was also the BBC brand with it, which was and still is very trusted and well-respected.”
Eventually, though, the BBC Micro ran out of steam. There were updates, among them the more expensive Master 128 and Master Compact that increased the amount of available RAM and promised backwards compatibility, but 16-bit computers such as the Amiga and Atari ST were dominating the home market and consoles were taking over the gaming space.
Acorn discontinued the BBC Micro in 1994 but its a testament to their design that so many continue to be used today.