The Acorn BBC model A was the successor of the Acorn Atom and its first name was Acorn Proton. It was a very popular computer in the UK and was widely used in schools, but it didn't have great success elsewhere (even though it did have great features, it was too expensive).
The Model A lacked some of the connectors of the Model B/B+ (User port, Tube, ...) on the underside.
This computer got its name because in 1980, the BBC decided to start a computer literacy television series. The network realized that, with more powerful and increasingly inexpensive microcomputers, it would soon be possible to create them with enough computing power to offer their owners personal hands-on experience with microcomputers at an affordable price.
The BBC considered the NewBrain computer and rejected it. Acorn and Sinclair Research, along with other companies, then submitted designs, and Acorn won. The BBC model B was then used almost universally in British schools from its birth into the 90's.
It was followed in 1982 by the Acorn BBC model B. The Model B had the same features but had 32 KB RAM (expandable to 64K).
The "Tube" was an expansion port which was designed to connect other processors to the BBC (6502, Z80, 68000 or ARM 1 RISC). An interface card was specially designed for the tube. It used another 6502 and a Z80.
One of its most popular peripherals was the "Torch" floppy disk unit, a 5.25" floppy disk drive with a Z80 which allowed the BBC to use CP/M software.
Acorn also made a "cheap" version of the BBC (fewer connectors & video modes) called Acorn Electron.
In 1985, the Acorn BBC Model B+ was released. The Model B+ had new features : 64K of RAM instead of 32 KB and internal circuitry for the Econet and Disk Drive as standard (both available as an upgrade in the models A and B). The later models included disk support as standard, using either an 8271 or a 1770 disk controller. There was also a B+ 128KB model (with and extra 4x16KB banks of "sideways RAM"). The B+ models had 48KB of ROM because they had an extra 16KB with the DFS. They used a MOS 6512A processor, but at the same 2MHz that the A and B models used.
It was then followed by the BBC Master.
Contributors: Gabriel Graça
BBC Model A / B / B+
END OF PRODUCTION
BUILT IN LANGUAGE
Full-stroke QWERTY keyboard, 64 keys, 10 function keys, arrow keys
Model 1 : 16 kb Model B : 32 kb Model B+ : 64 kb
80 x 32/25 (2 colors) / 40 x 32/25 (2 or 4 colors) / 20 x 32 (16 colors) / 40 x 25 (Teletext display)
640 x 256 (2 colors) / 320 x 256 (4 colors) / 160 x 256 (16 colors)
16 (8 colors + flashing option)
3 channels + 1 noise channel, 7 octaves
SIZE / WEIGHT
41 (W) x 34.5 (D) x 6.5 (H) cm / 3700 g
UHF TV out, BNC video out, RGB vide out, RS423, Cassette, Analogue In (DB15), Econet port, TUBE interface, 1Mhz BUS, User port, Printer port, Disk-drive connector
Built-in switching PSU
Controler card for 1 to 4 5''1/4 F.D. drives (1 400 F.F) Floppy disk unit 5''1/4 250 Ko. (3 900 F.F.) Numerical cassette recorder 100 Ko. (3 000 F.F.) Second 6502 microprocessor with card (3