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 if it did have great features, it was too expensive).
The Model A didn't have some of the connectors of the Model B/B+ (User port, Tube, ...) on the underside.
This computer got it's 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 it's 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, it was 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, internal circuitry for the Econet and Disk Drive as standard, they were both available as an upgrade in the models A and B. The later models included disk support as standard, using either a 8271 or 1770 disk controller.
It was then followed by the BBC Master.
Chris Carrigan adds:
The Model A and Model B were available at virtually the same time. The key difference was the amount of RAM. The 16KB in the meant that most of the video modes are not available and everybody bought Bs (much to Acorn's surprise). You could pre register and I still remember the awe with which we all read the "Provisional Specification". This machine really was a leap forward in capability.
Dave Gamble younger days memories:
I remember the launch of the BBC Micro model A and B. I first read about them in the U.K. computer press and as a 13 year old at that particular time, drooled over the spec of the model B machine. I then saw them used on the BBC TV program called "The Computer Program" host by Chris Searle. I wanted a BBC micro! But, they were £299 and £399 respectively for the Model A and B. I eventually "made do" with a Commodore 64. It is great testiment to the design of these machines, that they are still in use at my son's local primary school, albeit the "Master" version. AMAZING!
NAME BBC Model A / B / B+
MANUFACTURER Acorn Computer
TYPE Home Computer
ORIGIN United Kingdom
YEAR 1981
BUILT IN LANGUAGE BBC Basic
KEYBOARD Full-stroke QWERTY keyboard, 64 keys, 10 function keys, arrow keys
CPU MOS 6502
SPEED 1.8 MHz
RAM Model 1 : 16 kb
Model B : 32 kb
Model B+ : 64 kb
ROM 32 kb
TEXT MODES 80 x 32/25 (2 colors) / 40 x 32/25 (2 or 4 colors) / 20 x 32 (16 colors) / 40 x 25 (Teletext display)
GRAPHIC MODES 640 x 256 (2 colors) / 320 x 256 (4 colors) / 160 x 256 (16 colors)
COLORS 16 (8 colors + flashing option)
SOUND 3 channels + 1 noise channel, 7 octaves
SIZE / WEIGHT 41 (W) x 34.5 (D) x 6.5 (H) cm / 3700 g
I/O PORTS 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
POWER SUPPLY Built-in PSU
PERIPHERALS 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
PRICE £399 (UK 1983) - 1181 (France, February 1984)