1980s Vintage Computers
Acorn BBC Computers
Acorn was selected in 1981 by the British Broadcasting Corporation to manufacture a computer with Basic for homes and schools. This was part of a tie-in with the TV series 'The Computer Programme' and the aim was 10,000 computers in the first year. The resulting computer (the BBC A and BBC B) was far more successful than anticipated, and Acorn went on to become a major UK computer company for the remainder of the 1980s.
BBC A / BBC B
The BBC A was the original machine, featuring a cassette interface, 16K of RAM, 32K of ROM and cost £299. The BBC B was more powerful with 32K of RAM and built in tube, 1MHz bus and serial interfaces and cost £399. A disk interface using the 8271 controller with the Acorn Disk Filing System (DFS) was available for £120, this provided support for single density / FM disks only. Out-of-the box the BBC computer could run BASIC programs, and came with a tutorial-style User Guide which encouraged users to learn the features of the language stage by stage. The BBC B was very common in the UK, largely due to its take up by education authorities who overall bought many hundred thousand so that nearly every primary and secondary school had at least one. Similarly at home many enthusiasts caught on to the strengths of the BBC B and they sold well, but at a price at the high-end compared to say a Sinclair Spectrum. Several businesses bought them, sometimes as a general purpose computer, and sometimes because of the technical specification and ease of expansion. By the late 1990s every school had PCs and so most of the old BBC Bs became available and were either scrapped, given away or sold. Nowadays they are easily available at car boot sales, on eBay or in local papers.
The specification of the the BBC B was very advanced compared to similar home computers:
The standard options that could be built into the BBC B included:
Acorn developed a range of external modules in the same design as the BBC B, these included:
The second processor options allowed bigger programs to run, and also allowed the base unit to run graphics at maximum resolution with out using up system RAM or affecting program performance.
This machine was similar in looks to the BBC B, but provided either 64K or 128K of RAM. It came with a floppy disk interface included using a newer 1770 controller, thus adding support for double density / MFM disks. However it was launched with DFS so was limited to single density, until Acorn brought out ADFS which added double density support. The service manual states the B+ supports the same 8271 controller as the original BBC B for backwards compatibility.
The BBC B+ featured a 6512 processor which had the same op-codes as the 6502. The computer was introduced in 1985 for £499 but was not sufficiently better than a BBC B and so was not a great seller.
By 1985 the BBC B was lagging behind its competitors, so Acorn launched the Master as an enhanced series of machines, featuring a faster processor, far more memory, and a better keyboard. Crucially the Master was largely backwards compatible with software and expansion modules from the earlier BBC B machine.
The Master series was an-round improvement on the BBC B and was very popular. The basic machine in the range was the Master 128 (pictured at the top of this article), which as the name suggests has 128KB of RAM, and also 128KB of ROM. The ROM software include the View word-processor, a ViewSheet spreadsheet and two disk filing system ROMS (DFS and ADFS), as well as BBC BASIC. The Master's features include:
I also have a Master 512. This is a Master 128 fitted with a plug-in 80186 co-processor board with its own 512K of RAM (hence the name, although the machine actually has 640K of RAM in total!). This allows 16-bit software to be run, and was supplied with DR DOS+ and the GEM graphical desktop (with mouse support). My Master 512 was further enhanced by its previous owner with a Solidisk PC Plus board, which plugs into the 80186 board (making 3 layers in total). This contains a further 512K of RAM, but due to the need for I/O and ROM it reports 896K free. I have downloaded the DOS+ and GEM software from Yellow Pig which work fine.
There was also a Master Turbo, which like the Master 512 was a Master 128 plus a built in co-processor board, this time a 65C102 with its own 64K of RAM. This processor has 12 additional op-codes to the 6502, and at 4MHz it ran twice as fast as a BBC B. This meant that nearly all BBC 6502 based code could be run on the co-processor, but it ran much faster than on any other machine in the family, making this system the most desirable of them all.
The other machines in the range were:
Acorn then developed the Archimedes range of machines that used faster ARM processors and far larger memory with a graphical user interface, but also run BBC BASIC and so so again were popular with schools.
This page was last revised on: 03/06/08