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BBC Micro

The BBC Micro, also known as the beeb, was an early microcomputer.

In the early 1980s, the British Broadcasting Corporation started what became known as the BBC Computer Literacy Project. The project was started largely in response to an extremely influential BBC documentary The Mighty Micro, in which Dr. Christopher Evans from the UK National Physical Laboratory predicted the coming computer revolution and its impact to the economy, industry and lifestyle of the United Kingdom).

BBC wanted to base its project on a microcomputer capable of doing various things that they wanted to show in their TV series The Computer Programme (1981). The list of topics included programming, graphics, sound and music, Teletext, controlling hardware, artificial intelligence etc. It decided to badge a micro, then drew up a specification and asked for takers.

BBC discussed the issue with Sir Clive Sinclair, who tried to peddle the unsuccessful NewBrain[?] micro to them, but it came nowhere near the specification the BBC had drawn up, and was rejected. The BBC made appointments to see several other British computer manufacturers, including Dragon[?] and Acorn.

The Acorn team had been working on an upgrade to their existing Atom microcomputer. Known as the Proton it included better graphics and a faster 2MHz 6502 CPU. The machine was only in prototype form at the time, but the Acorn team, which relied largely on Cambridge students (such as the legendary Roger Wilson) worked through the night to get a working Proton together to show the BBC. The Acorn Proton was not only the only machine that came up to the BBC's specification, it also exceeded it in nearly every field. It was a clear winner.

The machine was released as the BBC Microcomputer in early 1982. The machine was wildly popular in the UK; as with Sinclair's ZX Spectrum, also released around that time, demand greatly exceeded supply and for some months there were long delays before customers received the machines they had ordered. A brief attempt to market the machine in the United States failed, due largely to the dominance of the Apple II. The success of the machine in the UK was largely due to its acceptance as an "educational" computer - the vast majority of UK schools used BBC micros to teach computer literacy and information technology skills.

Acorn anticipated the total sales to be around 12,000 units, but eventually more than 1 million BBC micros were sold.

The "Beeb", as it soon became known by its users, initally came in two models; the Model A at 235 UK pounds, and the Model B at 335 UK pounds.

The Model A had 16K of user RAM; the Model B had 32 K of user RAM, and included a number of extra I/O interfaces: A Serial and parallel printer port, and 8-bit I/O port, four analogue inputs and an expansion connector that enabled other hardware to be connected. There was also an interface called the Tube, that allowed a second processor to be added. (This was soon used in third-party add-ons, including a Zilog Z80 board and disk drive that allowed the BBC machine to run CP/M programs.)

Large numbers of games were written including the first version of the classic Elite, and a wide range of add-ons and expansions were available; as the machine had provision for floppy disk drives and networking hardware to be added; there were also sockets for the addition of extra ROM to the system.

Even today, (October 2001) thanks to its ready expandability and I/O functions, there are still numbers of BBCs in use, and a community of dedicated users finding new things to do with the old hardware.

A cut-down version of the BBC Micro, intended more for game playing was the Acorn Electron; games were wriiten specially for the Electron's more limited hardware, but they could also be run on the BBC.


  • 2 MHz MOS Technologies 6502 processor
  • 32 KB ROM (16 KB OS, 16 KB BBC BASIC)
  • 32 KB RAM (16 KB in model A, 64 KB in model B+)
  • Graphics modes (see below):
    • mode 0: 640x256 (80x32), 2 colors
    • mode 1: 320x256 (40x32), 4 colors
    • mode 2: 160x256 (20x32), 8 colors + 8 "blinking colors"
    • mode 3: 640x200 (80x25), 2 colors
    • mode 4: 320x256 (40x32), 2 colors
    • mode 5: 160x256 (20x32), 4 colors
    • mode 6: 320x200 (40x25), 2 colors
    • mode 7: 80x32 teletext, 8 colors and teletext graphics using the SAA5050 Teletext chip
  • 4 independent sound channels (one noise and 3 melodic) using the 74869 sound chip
  • Built-in hardware support included: pluggable ROM chips, tape deck (with motor control), printers (Centronics), serial communication (a proprietary RS-432 interface), diskette drive (requiring an extra ROM), TV set or monochrome/color monitors, twin proprietary analogue joysticks, a second processor (a 3 MHz 6502, a Z80 (adding CP/M capability), a 16032 and an ARM1 processors were launched) and a "user port" connected to the bus.

The video display could be switched between 8 different video modes, with varying resolutions and numbers of colours available:

ModeResolutionTextColoursMemory used
0640 by 25680 by 32220K
1320 by 25640 by 32420K
2160 by 25620 by 321620K
3 - 80 by 25216K
4320 by 25640 by 32210K
5160 by 25620 by 32410K
6 - 40 by 2528K
7teletext40 by 2516 1K

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