BBC Micro

The British Broadcasting Corporation Microcomputer System, or BBC Micro, is a series of microcomputers and associated peripherals designed and built by the Acorn Computer company in the 1980s for the BBC Computer Literacy Project, operated by the British Broadcasting Corporation. Designed with an emphasis on education, it was notable for its ruggedness, expandability, and the quality of its operating system. An accompanying 1982 television series, The Computer Programme, featuring Chris Serle learning to use the machine, was also broadcast on BBC 2.

After the Literacy Project’s call for bids for a computer to accompany the TV programmes and literature, Acorn won the contract with the Proton, a successor of its Atom computer prototyped at short notice. Renamed the BBC Micro, the system was adopted by most schools in the United Kingdom, changing Acorn’s fortunes. It was also successful as a home computer in the UK, despite its high cost. Acorn also employed the machine to simulate and develop the ARM architecture which, many years later, has become hugely successful for embedded systems, including tablets and cellphones. In 2013 ARM was the most widely used 32-bit instruction set architecture.

While nine models were eventually produced with the BBC brand, the phrase “BBC Micro” is usually used colloquially to refer to the first six (Model A, B, B+64, B+128, Master 128, and Master Compact), excluding the Acorn Electron; subsequent BBC models are considered part of Acorn’s Archimedes series.

During the early 1980s, the BBC started what became known as the BBC Computer Literacy Project. The project was initiated partly in response to an ITV documentary series The Mighty Micro, in which Christopher Evans of the UK’s National Physical Laboratory predicted the coming microcomputer revolution and its effect on the economy, industry, and lifestyle of the United Kingdom.

The BBC wanted to base its project on a microcomputer capable of performing various tasks which they could then demonstrate in the TV series The Computer Programme. The list of topics included programming, graphics, sound and music, teletext, controlling external hardware, and artificial intelligence. It developed an ambitious specification for a BBC computer, and discussed the project with several companies including Acorn Computers, Sinclair Research, Newbury Laboratories, Tangerine Computer Systems, and Dragon Data.

The Acorn team had already been working on a successor to their existing Atom microcomputer. Known as the Proton, it included better graphics and a faster 2 MHz MOS Technology 6502 central processing unit. The machine was only at the design stage at the time, and the Acorn team, including Steve Furber and Sophie Wilson, had one week to build a working prototype from the sketched designs. The team worked through the night to get a working Proton together to show the BBC. Not only was the Acorn Proton the only machine to match the BBC’s specification, it also exceeded it in nearly every parameter. Based on the Proton prototype the BBC signed a contract with Acorn as early as February 1981; by June the BBC Micro’s specifications and pricing were decided.

The machine was released as the BBC Microcomputer on 1 December 1981, although production problems pushed delivery of the majority of the initial run into 1982. Nicknamed “the Beeb”, it was popular in the UK, especially in the educational market; about 80% of British schools had a BBC microcomputer.

BYTE called the BBC Micro Model B “a no-compromise computer that has many uses beyond self-instruction in computer technology”. It called the Tube interface “the most innovative feature” of the computer, and concluded that “although some other British microcomputers offer more features for a given price, none of them surpass the BBC … in terms of versatility and expansion capability”. As with Sinclair’s ZX Spectrum and Commodore’s Commodore 64, both released later in 1982, demand greatly exceeded supply. For some months, there were long delays before customers received the machines they had ordered.

Efforts were made to market the machine in the United States and West Germany. By October 1983, the US operation reported that American schools had placed orders with it totalling $21 million. In October 1984, while preparing a major expansion of its US dealer network, Acorn claimed sales of 85 per cent of the computers in British schools, and delivery of 40,000 machines per month. That December, Acorn stated its intention to become the market leader in US educational computing. The New York Times considered the inclusion of local area networking to be of prime importance to teachers. The operation resulted in advertisements by at least one dealer in Interface Age magazine, but ultimately the attempt failed. The success of the machine in the UK was due largely to its acceptance as an “educational” computer – UK schools used BBC Micros to teach computer literacy, information technology skills and a generation of games programmers. Acorn became more known for its model B computer than for its other products. Some Commonwealth countries, including India, started their own computer literacy programs around 1987 and used the BBC Micro, a clone of which was produced by Semiconductor Complex Limited and named the SCL Unicorn.

The Model A and the Model B were initially priced at £235 and £335 respectively, but increased almost immediately to £299 and £399 due to higher costs. The Model B price of nearly £400 was roughly £1200 (€1393) in 2011 prices. Acorn anticipated the total sales to be around 12,000 units, but eventually more than 1.5 million BBC Micros were sold.

The cost of the BBC Models was high compared to competitors such as the ZX Spectrum and the Commodore 64, and from 1983 on Acorn attempted to counter this by producing a simplified but largely compatible version intended for game playing, the 32K Acorn Electron.

During 1986, Acorn followed up with the BBC Master, which offered memory sizes from 128 KB and many other refinements which improved on the 1981 original. It had essentially the same 6502-based BBC architecture, with many of the upgrades that the original design had intentionally made possible (extra ROM software, extra paged RAM, second processors) now included on the circuit board as internal plug-in modules.

The built-in ROM-resident BBC BASIC programming language interpreter realised the system’s educational emphasis and was key to its success; not only was it the most comprehensive BASIC compared to other contemporary implementations but it ran very efficiently and was therefore fast. Advanced programs could be written without resorting to non-structured programming or machine code (necessary with many competing computers). Should one want or need to do some assembly programming, BBC BASIC featured a built-in assembler that allowed a very easy mixture of BBC BASIC and assembler for whatever processor BBC BASIC was operating on.

When the BBC Micro was released, many competing home computers used Microsoft BASIC, or variants typically designed to resemble it. Compared to Microsoft BASIC, BBC BASIC featured IF…THEN…ELSE, REPEAT…UNTIL, named procedures and functions, but retained Goto and GOSUB for compatibility. It also supported high-resolution graphics, four-channel sound, pointer-based memory access (borrowed from BCPL) and rudimentary macro assembly. Long variable names were accepted and distinguished completely, not just by the first two characters.

Acorn produced their own 32-bit Reduced Instruction Set (RISC) CPU during 1985, the ARM1. Furber composed a reference model of the processor on the BBC Micro with 808 lines of BASIC, and ARM Holdings retains copies of the code for intellectual property purposes. The first prototype ARM platforms, the ARM Evaluation System and the A500 workstation, functioned as second processors attached to the BBC Micro’s Tube interface. Acorn staff developed the A500’s operating system in situ through the Tube until, one by one, the on-board I/O ports were enabled and the A500 ran as a stand-alone computer. With an upgraded processor this was eventually released during 1987 as four models in the Archimedes series, the lower-specified two models (512 KB and 1 MB) continuing the BBC Microcomputer brand with the distinctive red function keys. Although the Archimedes ultimately was not a major success, the ARM family of processors has become the dominant processor architecture in mobile embedded consumer devices, particularly mobile telephones.

Acorn’s last BBC-related model, the BBC A3000, was released in 1989. It was essentially a 1 MB Archimedes back in a single case form factor.

The BBC Domesday Project, a pioneering multimedia experiment, was based on a modified version of the BBC Micro’s successor, the BBC Master.

Musician Vince Clarke of the British synth pop bands Depeche ModeYazoo, and Erasure used a BBC Micro (and later a BBC Master) with the UMI music sequencer to compose many hits. In music videos from the 1980s featuring Vince Clarke, a BBC Micro is often present or provides text and graphics such as a clip for Erasure’s “Oh L’Amour”. The musical group Queen used the UMI Music Sequencer on their record A Kind of Magic. The UMI is also mentioned in the CD booklet. Other bands who have used the Beeb for making music are A-ha and the reggae band Steel Pulse. Paul Ridout is credited as “UMI programmer” on Cars’ bassist/vocalist Benjamin Orr’s 1986 solo album, The Lace. Other UMI users included Blancmange, Alan Parsons and Mutt Lange. Black Uhuru used the Envelope Generator from SYSTEM software (Sheffield) running on a BBC Micro, to create some of the electro-dub sounds on Try It (Anthem album 1983).

The BBC Micro was used extensively to provide graphics and sound effects for many early 1980s BBC TV shows. These included, notably, series 3 and 4 of The Adventure Game; the children’s quiz game “First Class” (where the onscreen scoreboard was provided by a BBC Micro nicknamed “Eugene”); and numerous 1980s episodes of Doctor Who including “Castrovalva”, “The Five Doctors”, and “The Twin Dilemma”.

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