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File:Bbcmicro 2214.jpg

The BBC Microcomputer System (aka "BBC" or just "Beeb"), built by Acorn Computers under the auspices of (naturally) The BBC, was one of the main competitors in the 1980s home computer wars in Britain, the others including the Commodore 64 and ZX Spectrum. The Beeb was originally the cornerstone of the BBC Computer Literacy Project and was intended to be an educational tool and the vehicle for the Project's BBC BASIC language; it certainly turned out to be that, but also became known as a gaming platform and an early technology for computer special effects.

First released in 1981, its basic specs were comparable to that of its main competitors. Processor speed: 2 MHz. RAM: 16 kb (Model A); 32 kb (Model B). Graphics: 1, 2, or 4-bit colour modes (2, 4 or 16 logical colours) from a palette of 8 actual colours. Like the Apple II and Commodore 64, but unlike the Spectrum and Amstrad CPC, the Beeb clocked its RAM at twice the speed of its CPU and therefore was able to switch alternately between CPU and video circuits without a speed penalty.

The Beeb’s peripheral interfaces were something else entirely. True to its lofty goals, the fully-upgraded Model B [1] featured:

  • TTL RGB and composite video output as well as the usual UHF TV modulator.
  • Standard serial and parallel ports (for printers or whatever took your fancy).
  • The best disk interface and filing system of any 8-bit home computer.
  • Logic inputs and outputs for controlling devices.
  • Analogue-to-digital converter inputs for measurements (and analogue joysticks, oh yes!).
  • A 1 MHz bus for fast data acquisition
  • Econet (Acorn'’s proprietary networking system).
  • And last but not least, the Tube — an advanced bus which could support and utilise a second processor.

Second processors were actually available — as well as the official Acorn model (shown off in the promo literature but rarely bought), there was the Torch Systems Z80 board (which could run their version of CP/M and business software), and a few other third-party systems. As it was, the Tube was really a developer feature, included to aid future prototyping — the ARM processor was tested on it and the Acorn Archimedes developed with its aid.

Like most 8-bit home computers, the Beeb featured a BASIC interpreter (the aforementioned BBC BASIC) which was accessed directly from the command line. It also featured a native assembler for writing machine code.

The Beeb remains a cult classic today mainly because of its remarkable customisability. Network interfaces, extra tape and disk drives, and custom peripherals could be added easily. Several prominent early adopters, such as author Terry Pratchett, took this to its logical extreme and ended up with a machine at the centre of a dozen custom circuitboards that would turn the lights on, check the weather via a Teletext adaptor and display it on the screen, and play a fanfare as soon as he entered the room. After a while Pratchett forgot exactly what component did what and the machine seemed like some mysterious organic whole, inspiring the self-aware computer HEX from Discworld.

It also saw use in the entertainment industry, creating visual effects and synthesised music. One prominent use was by Queen in their song A Kind of Magic. The BBC itself made as extensive use of this facility as it could, probably so they could be seen "eating their own dogfood", but also for practical reasons. While it depended on what you wanted, you could usually whip up programs for producing effects and captions in-house in a very short space of time. These could then be re-used on demand — while productions had to jostle for time on one of the BBC's Quantel systems, they could have their own BBC Micro(s) as required.

The BBC Micro was superseded by the BBC Master (AKA Beeb Master or just Master) in 1986 and the 32-bit ARM-based Acorn Archimedes in 1987 before finally being discontinued in 1994.


Specifications:

Processors

  • CPU: MOS 6502, 2 Mhz.
  • GPU: Motorola 6845 + custom circuitry.
  • Sound: Texas Instruments SN76489.

Memory

  • Model A: 16K.
  • Model B: 32K.
  • Model B+ (1985): 64K or 128K.

Display

  • 160*256, 320*256, or 640*256 resolution.
  • Up to 8 colours.

Sound

  • Four channels — three square waves, one noise generator.

Games:


Along with every other 8-bit micro, the Beeb had a lot of blatant rip-offs of popular U.S. and Japanese games, along with the odd official port or rewrite.

Notes

  1. (most Model As were upgraded at some point — the 16k of memory was just one of the things that they were missing, and few programmers were prepared to constrain themselves to create software that would run on them)
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