--- title: Acorn Computer BBC Model A / B / B+ categories: - Computers types: - Home Computer origins: - United Kingdom years: - '1981' cpus: - MOS 6502 params: name: BBC Model A / B / B+ image: /media/museum/photos/acorn_bbcb_system_s1.jpg logo: /media/museum/logos/acorn_bbcb_logo.gif company: /companies/acorn-computer company_name: Acorn Computer specs: - label: NAME value: BBC Model A / B / B+ - label: MANUFACTURER value: Acorn Computer - label: TYPE value: Home Computer - label: ORIGIN value: United Kingdom - label: YEAR value: '1981' - label: END OF PRODUCTION value: Unknown - label: BUILT IN LANGUAGE value: BBC Basic - label: KEYBOARD value: Full-stroke QWERTY keyboard, 64 keys, 10 function keys, arrow keys - label: CPU value: MOS 6502 - label: SPEED value: 1.8 MHz - label: RAM value: |- Model 1 : 16 kb\ Model B : 32 kb\ Model B+ : 64 kb - label: ROM value: 32 kb - label: TEXT MODES value: 80 x 32/25 (2 colors) / 40 x 32/25 (2 or 4 colors) / 20 x 32 (16 colors) / 40 x 25 (Teletext display) - label: GRAPHIC MODES value: 640 x 256 (2 colors) / 320 x 256 (4 colors) / 160 x 256 (16 colors) - label: COLORS value: 16 (8 colors + flashing option) - label: SOUND value: 3 channels + 1 noise channel, 7 octaves - label: SIZE / WEIGHT value: 41 (W) x 34.5 (D) x 6.5 (H) cm / 3700 g - label: I/O PORTS value: 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 - label: POWER SUPPLY value: Built-in switching PSU - label: PERIPHERALS value: |- 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 - label: PRICE value: £399 (UK 1983) - 1181 (France, February 1984) tabs: - photos - adverts - hardware - connectors - software - emulators - links - docs forum_thread: 48 photos: - title: BBC MODEL B subtitle: '' text: '' image: /media/museum/photos/acorn_bbcb_system_s2.jpg - title: SIDE VIEWS subtitle: '' text: '' image: /media/museum/photos/acorn_bbcb_sides_s1.jpg - title: KEYBOARD CLOSE-UP subtitle: '' text: '' image: /media/museum/photos/acorn_bbcb_keyboard_s1.jpg - title: BACK PANEL subtitle: '' text: The Econet interface isn't installed. image: /media/museum/photos/acorn_bbcb_rearconnect_s1.jpg - title: UNDERNEATH CONNECTORS subtitle: '' text: |- **(1)** Tube expansion connector\ **(2)** 1 MHz bus connector\ **(3)** User port\ **(4)** Printer connector\ **(5)** Floppy disk drive interface\ **(6)** Auxiliary power output, mainly intended for the FDD unit. image: /media/museum/photos/acorn_bbcb_underneath_s1.jpg - title: OPENED subtitle: '' text: '' image: /media/museum/photos/acorn_bbcb_opened_s1.jpg - title: MOTHERBOARD subtitle: '' text: |- You may download the complete diagram of the motherboard. **(1)** FDD controller\ **(2)** NEC 7002 Analogue to digital converter\ **(3)** 6850 Serial interface adapter (ACIA)\ **(4)** Cassette and RS-423 Ferranti custom chip\ **(5)** 6502 CPU\ **(6)** 6845 CRT controller\ **(7)** SAA5050 Teletext chip\ **(8)** 32 KB RAM chips (16x4116)\ **(9)** Custom chip in charge of bus and memory management\ **(10)** Two 6522s manage the various system I/O\ **(11)** Acorn DOS and BBC BASIC 16 KB ROMs\ **(12)** Underneath connectors. image: /media/museum/photos/acorn_bbcb_mainboard_s1.jpg - title: PROTON VERSION subtitle: '' text: |- Rare picture of a Proton version.\ Notice that the Reset key at the right hand side of the function keys was replaced with a Break key in the Model B version. Thanks to **Jonathan Bluestone** image: /media/museum/photos/acorn_bbc_proton_s1.jpg - title: VIGLEN VERSION subtitle: '' text: |- Viglen company made this improved version of the Model B. Major changes were:\ \- A new case with separate keyboard,\ \- 2 built-in 5.25" FD drives,\ \- Additional ROM programs,\ \- Separate power supply unit. Thanks to **Mike Holdaway** image: /media/museum/photos/acorn_bbcb_biglen_s1.jpg - title: BASICODE, THE TRANSMISSION OF PROGRAMS BY RADIO subtitle: '' text: |- The BBC was one of the systems which benefited from the Basicode standard. The principle is quite simple: every user of a computer can create a program in BASIC by respecting Basicode's rules (limited number of instructions, line length limited to 60 characters, etc.). This program is then sent through radio broadcasts and recorded by the listeners who can then transfer it to their computer. The first broadcasts took place in 1978 for 4 types of computers: Apple 2, Edixy Sorcerer, Commodore PET and Tandy TRS 80. Basicode was then improved and became Basicode 2. In 1983, the listeners of Belgium, Germany, Denmark, England and France regularly loaded numerous programs successfully. In England, the BBC broadcast called "Chip Chop" was very appreciated by the amateurs of Basicode. It distributed a cassette tape containing instructions of use on one side and 18 demonstration programs on the other one. image: /media/museum/photos/basicode.jpg - title: BBC BROADCAST subtitle: '' text: |- The famous "Making the most of your micro" BBC broadcast featuring the Acorn BBC computer. The BBC wanted to have their own computer to promote through these broadcasts so they signed a deal with Acorn to produce the Proton under the BBC name. image: /media/museum/photos/acorn_bbc_emission.jpg - title: BBC NETWORK subtitle: '' text: |- In this university, the network is composed of 16 computers and color monitors, a single disk drive and a printer. Every user shares the resources of the same disk drive without any waiting time, as well as a unique printer through a spooler. image: /media/museum/photos/reseau.jpg adverts: - title: UK ADVERT (JULY 1984) subtitle: '' text: '' image: /media/museum/pubs/acorn-bbc_uk-pub_july-1984.jpg - title: UK ADVERT subtitle: '' text: |- From Personal Computer World, October 1983 Here are some answers:\ "The BBC Microcomputers are the limousines of home computers. The graphics are probably the best' of any machine in this class. You are paying for Ii smart machine which would not disgrace the home of a professional."\ *Video World., Feb. '83.* "Its design has given the BBC Micro an unrivalled potential for business, educational and serious home applications. It has been equipped to function as the heart of a system which can be expanded 10 suit its owner's need?"\ *Which Micro & Software Review, Feb. '81* "The most attractive and exciting feature of the BBC Microcomputer is its enormous potential for expansion which will allow a higly expansive system to be built-up?"\ *Which Micro, June '82.* "They (the graphics) are tremendously exciting, and they are one of the features that make this machine stand out head and shoulders above everything else that is available in the market place at this time"\ *Educalional Computing, May '82* "It is expandable and has a powerful BASIC. It has superb sound and graphics, the software is readily available and the price is righ"\ *BBC Micro owner from Hampshire.* "The basics are easy to follow. My wife has developed a program for teaching our daughter French vocabulary. Our daughter uses it mainly for games and simple programming"\ *BBC Micro owner from Co. Durham.* "It is a very powerful computer, My husband has written his own data base. I have been writing programs and programming games. Even the children have written small programs."\ *BBC Micro owner from Devon.* "No other computer can offer such ease of use when dealing with complex sound effects."\ *Which Micro, June '82.* "It isn't often a journalist can sit down to write about a computer with the certain knowledge that he has never seen a nicer machine."\ *Personal Computer World, Dec. '82* "It has got huge potential. Besides playing the games, the whole family are learning basic programming."\ *A BBC Micro owner from Staffordshire.* "Everything possible seems to have been done to ensure that this is not a 'dead end' machine.."\ *Personal Computer World, July '82.* image: /media/museum/pubs/acorn_bbc_pub_s1.jpg - title: SECOND 6502 subtitle: '' text: |- The Second Processor option features, in a separate case, a 3 MHz 6502 processor and 64 KB of RAM. It was connected to the BBC system through the Tube channel. The BBC RAM was then used as video RAM, so the full memory area of the Second Processor was available for user programs.\ Two ROMs was also delivered. The first one holded a new BASIC version called HI-BASIC that made full use of the new memory configuration. The other updated disc or Econet filling system. Courtesy of **8BS.com** image: /media/museum/pubs/acorn_bbc_secondprocadv_1.jpg - title: F.D. UNIT ADVERT subtitle: '' text: |- BBC floppy disc unit was delivered with a 8271 FD controller chip and a Filing System software in ROM to be fitted into the BBC system.\ Two versions of F.D. units were available:\ \- A single drive unit, single side, single density, 100 KB space.\ \- A dual drive version, double side, double density, 800 KB space. Courtesy of **8BS.com** image: /media/museum/pubs/acorn_bbc_fdpub_1.jpg - title: 'FRENCH ADVERT #1' subtitle: '' text: |- "Carefully, one last time... I compared everything and I offered myself a BBC" Lucky guy, he must be rich at more than 6300fr the BBC... At the end of the text we can read : "The price : 6300fr maximum. Of course it's not given. More expensive than some (but I had already eliminated them)." !! At least they are honest. image: /media/museum/pubs/acorn_bbc_pub_1.jpg - title: 'FRENCH ADVERT #2' subtitle: '' text: |- "A step toward the future" Hmmmm..... image: /media/museum/pubs/acorn_bbc_pub_jcs_1.jpg hardware: - title: ROM PAGING CARD subtitle: '' text: There are four ROM sockets in the standard BBC but the OS supports up to 16 sockets. The Watford 13 ROM board allows up to 16 16 KB ROMs to be selected at any one time by the OS. image: /media/museum/hardware/acorn_bbcb_romcard_s1.jpg - title: LIGHT PEN subtitle: from RM Electronics text: This lightpen is connected to the "Analogue In" socket. It is delivered with some software, including "Color Graphic". image: /media/museum/hardware/acorn_bbc_lightpen.jpg - title: VOLTMACE DELTA CONTROLLERS subtitle: '' text: 'Voltmace modified its Database videogame system controllers to be sold for micro-computers, mainly Acorn systems : BBC and Electron (with Plus-1 interface). As the keypad was of no use anymore, it was reduced to only 3 fire buttons.' image: /media/museum/hardware/voltmace_joysticks.jpg - title: 5''1/4 DISK-DRIVE subtitle: '' text: '' image: /media/museum/hardware/acorn_bbc_disk-drive_1.jpg - title: BBC FLOPPY DISK-DRIVE subtitle: '' text: It was rather slow and used 100 KB floppy disks. image: /media/museum/hardware/acorn_bbc_floppy.jpg - title: CUMANA F.D. UNIT subtitle: '' text: Cumana CSX-400S. BBC Compatible 5.25" disk drive. Selectable 40/80 track, single/double sided, 200/400 KB capacity. image: /media/museum/hardware/acorn_bbc_cumanadrive_1.jpg - title: TORCH Z80 DISK PACK subtitle: '' text: |- The Torch Disk Pack made it possible for the BBC user to run the CP/M operating system and use its vast range of software. The system included a Z80 microprocessor and 64 KB of additional memory. Some of the components were installed in the BBC computer. **(1)** The Z80 microprocessor replaced the BBC's 6502.\ **(2)** 64 KB RAM dedicated to the Z80 and CP/M.\ **(3)** The Torch card was inserted into the BBC case and fixed with these fasteners.\ **(4)** The Z80 card was connected to the BBC through the 'tube' interface.\ **(5)** Some additional components had to be inserted on the motherboard.\ **(6)** Two 5.25'' 400 KB disk drives. Each drive was seen by CP/M as two 200 KB virtual drives.\ **(7)** Drive cable connected to the BBC disk drive interface.\ **(8)** These power cords had to be disconnected from the BBC motherboard when the Torch system was connected.\ **(9)** Power is supplied by the Torch unit, the BBC power supply no longer being used.\ **(10)** Power wires coming from the Torch power supply.\ **(11)** ROM chip holding the CP/M operating system (Torch called it MCP). image: /media/museum/hardware/acorn_bbc_torchdiskpack_1.jpg connectors: - title: BACK CONNECTORS subtitle: '' text: looking at the BBC back panel. image: /media/museum/connectors/acorn_bbcb_connectors_s1.jpg - title: JOYSTICKS CONNECTOR subtitle: '' text: |- A pair of analog joysticks can be connected to this unique 15-pin connector of which only 12 are used. The connector is found at the back of the computer. The connections of both joysticks are perfectly symmetric. (1) Right fire button\ (2) Right up/down moves\ (3) Right left/right moves\ (4) Left up/down moves\ (5) Left left/right moves\ (6) Left fire button image: /media/museum/connectors/acorn_bbcb_connjoys_s1.jpg screenshots: - title: BOULDER DASH subtitle: '' text: '' image: /media/museum/software/acorn_bbc_boulderdash_ss.gif - title: CITADEL 2 subtitle: '' text: '' image: /media/museum/software/acorn_bbc_citadel2_ss.gif - title: CHUCKY EGG subtitle: '' text: '' image: /media/museum/software/acorn_bbc_chucky-egg_ss.gif - title: CYLON ATTACK subtitle: '' text: '' image: /media/museum/software/acorn_bbc_cylon-attack_ss.gif - title: DAMBUSTERS subtitle: '' text: '' image: /media/museum/software/acorn_bbc_dambusters_ss.gif - title: ELITE subtitle: '' text: '' image: /media/museum/software/acorn_bbc_elite_ss.gif - title: THE WAY OF THE EXPLODING FIST subtitle: '' text: '' image: /media/museum/software/acorn_bbc_exploding_ss.gif - title: FORTRESS subtitle: Zaxxon clone text: '' image: /media/museum/software/acorn_bbc_fortress_ss.gif - title: GRAND PRIX CONSTRUCTION SET subtitle: Title screen text: '' image: /media/museum/software/acorn_bbc_grandprix-cs_ss.gif - title: GRAND PRIX CONSTRUCTION SET subtitle: '' text: '' image: /media/museum/software/acorn_bbc_grandprix-cs_ss2.gif - title: MAGIC MUSHROOMS subtitle: '' text: '' image: /media/museum/software/acorn_bbc_magic-mushrooms_ss.gif - title: MATCHDAY subtitle: '' text: '' image: /media/museum/software/acorn_bbc_matchday_ss.gif - title: METEORS subtitle: '' text: '' image: /media/museum/software/acorn_bbc_meteors_ss.gif - title: MONSTERS subtitle: '' text: '' image: /media/museum/software/acorn_bbc_monsters_ss.gif - title: NEVRYON subtitle: '' text: '' image: /media/museum/software/acorn_bbc_nevryon_ss.gif - title: RAID OVER MOSCOW subtitle: '' text: '' image: /media/museum/software/acorn_bbc_raid_ss.gif - title: RAVENSKULL subtitle: '' text: '' image: /media/museum/software/acorn_bbc_ravenskull_ss.gif - title: SIMCITY subtitle: '' text: '' image: /media/museum/software/acorn_bbc_simcity_ss.gif - title: WAR subtitle: Title screen text: '' image: /media/museum/software/acorn_bbc_war_ss.gif - title: ZALAGA subtitle: Galaga clone text: '' image: /media/museum/software/acorn_bbc_zalaga_ss.gif - title: ZANY KONG subtitle: Donkey-Kong clone text: '' image: /media/museum/software/acorn_bbc_zany-kong_ss.gif emulators: - title: The BBC Lives ! url: http://www.nvg.org/bbc/emulators.php3 platform: MS DOS text: This excellent site has a complete list of Acorn systems emulators - title: BeebEm url: http://members.aol.com/mikebuk/beebem/index.html platform: Windows text: The most popular emulator - title: Horizon emulator url: http://www.chrislam.co.uk/ platform: Apple text: homepage for Horizon - title: BeebEm url: http://members.aol.com/mikebuk/beebem/index.html platform: Unix / Linux text: Unix version of this popular emulator - title: BeebIt url: http://www.voyager.co.nz/~mikef/bbc.htm platform: RISC OS text: There had to be a BBC emulator for Acorn 32-bit computers !! - title: Acorn BBC Model B ROMs url: http://www.geocities.com/SiliconValley/Lakes/7207/ROMs.htm platform: Other platform text: '' - title: Jon's Web Page url: http://www.dookie.demon.co.uk/ platform: BEOS text: A BeOS port of BeebEM links: - title: Acorn-BBC Master 128 CMOS Battery Pack and Configuration url: http://www.argonet.co.uk/users/lionels/CompNyb/TechStuff/8-Bit/Master128/128BatConfig.html text: Help for those who want to repair the CMOS battery pack of restore the BBC Master 128 configuration - title: Acornusers.org url: http://www.acornusers.org/ text: The acornusers.org server hosts several Acorn web sites - title: BBC Documentation Project url: http://www.bbcdocs.com/ text: Full of on-line documentation. Quite useful !! - title: comp.sys.acorn.games FAQ url: http://www.landfield.com/faqs/acorn/games/ text: newsgroup FAQ - title: RetroBBC url: http://www.strafom.force9.co.uk/bbc/Retrobbc/Index.htm text: Mainly a software archive. Cool ! - title: Sharx place url: http://www.users.waitrose.com/~sharx/beeb.htm text: BBC Micro - Games Archive - title: The BBC and Master Computer Public Domain Library url: http://8bs.com/ text: Lots of stuff to see and download - title: The BBC Lives! url: http://bbc.nvg.org/ text: The net's largest site catering for enthusiasts of Acorn's range of 8-bit micros - title: The Stairway to Hell url: http://www.stairwaytohell.com/ text: Electron and BBC support. Excellent site with a lot of stuff ! - title: The Unofficial Acorn Computer User WWW Server url: http://www.poppyfields.net/acorn/ text: '' - title: Web Wiz CAPTCHA url: http://www.webwizcaptcha.com text: Programming of Acorn computers docs: - title: BBC WELCOME BOOKLET url: http://www.bbcdocs.com/ cover: /media/museum/docs/couvs/acorn_bbc_welcome-booklet.jpg text: |- [**BBC WELCOME BOOKLET**](http://www.bbcdocs.com/)written by Acorn  compiled/archived by Mark de Weger\  type of document : PDF\  source : [BBC Documentation Project](http://www.bbcdocs.com/) - title: BBC USER GUIDE url: http://www.bbcdocs.com/ cover: /media/museum/docs/couvs/acorn_bbc_user-guide.jpg text: |- [**BBC USER GUIDE**](http://www.bbcdocs.com/)written by John Coll  compiled/archived by Mark Usher\  type of document : RTF\  source : [BBC Documentation Project](http://www.bbcdocs.com/) - title: THE ADVANCED USER GUIDE url: http://www.bbcdocs.com/ cover: /media/museum/docs/couvs/acorn_bbc_advanced-user-guide.jpg text: |- [**THE ADVANCED USER GUIDE**](http://www.bbcdocs.com/)written by Bray, Dicken & Holmes  compiled/archived by Gordon L Craig\  type of document : RTF\  source : [BBC Documentation Project](http://www.bbcdocs.com) - title: BBC B SERVICE MANUAL url: http://www.bbcdocs.com/ cover: /media/museum/docs/couvs/acorn-bbc-b_service-manual.jpg text: |- [**BBC B SERVICE MANUAL**](http://www.bbcdocs.com/)written by Acorn  compiled/archived by Mark Usher\  type of document : RTF\  source : [BBC Documentation Project](http://www.bbcdocs.com) - title: BBC B+ SERVICE MANUAL url: http://www.bbcdocs.com/ cover: /media/museum/docs/couvs/acorn-bbc-b_service-manual.jpg text: |- [**BBC B+ SERVICE MANUAL**](http://www.bbcdocs.com/)written by Acorn  compiled/archived by Mark Usher / Andreyro\  type of document : RTF\  source : [BBC Documentation Project](http://www.bbcdocs.com) related: - /museum/acorn-computer-atom - /museum/acorn-computer-bbc-master - /museum/acorn-computer-bbc-master-aiv - /museum/acorn-computer-bbc-master-compact - /museum/acorn-computer-electron oc_id: 29 source: url: https://web.archive.org/web/20230604045601/http://www.old-computers.com/museum/computer.asp?c=29 date: '2023-06-04' --- The Acorn BBC model A was the successor of the [Acorn Atom](/museum/acorn-computer-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](/museum/grundy-new-brain/) 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](/museum/acorn-computer-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