16–32 KiB (Model A/B)
64–128 KiB (Model B+)
128 KiB (Master)
Plus 32–128 KB ROM, expandable to 272 KiB
100–800 KB (DFS)
160–1280 KB (ADFS floppy disks)
20 MB (ADFS hard disk)
PAL/NTSC, UHF/composite/TTL RGB
640×256, 8 colours (various framebuffer modes)
78×75, 8 colours (Teletext)
Texas Instruments SN76489, 4 channels, mono
TMS5220 speech synthesiser with phrase ROM (optional)
Keyboard, twin analogue joysticks with fire buttons, lightpen
RS-423 serial, user parallel,
1 MHz bus, Tube second processor interface
The British Broadcasting Corporation
Microcomputer System, or BBC
Micro, is a series of microcomputers and associated peripherals
designed and built by the Acorn Computer company for the
Literacy Project, operated by the British Broadcasting Corporation.
Designed with an emphasis on education, it was notable for its
ruggedness, expandability, and the quality of its operating system. An
accompanying 1982 television series "The Computer Programme" featuring
Chris Serle learning to use the machine was also broadcast on
After the Literacy Project's call for bids for a computer to accompany
the TV programmes and literature, Acorn won the contract with the
Proton, a successor of its Atom computer prototyped at short notice.
BBC Micro, the system was adopted by most schools in the
United Kingdom, changing Acorn's fortunes. It was also moderately
successful as a home computer in the UK despite its high cost. Acorn
also employed the machine to simulate and develop the ARM architecture
which, many years later, has become hugely successful for embedded
systems, including tablets and cellphones. In 2013 ARM was the most
32-bit instruction set architecture.
While nine models were eventually produced with the
BBC brand, the
BBC Micro" is usually used colloquially to refer to the first
six (Model A, B, B+64, B+128, Master 128, and Master Compact),
excluding the Acorn Electron; subsequent
BBC models are considered as
part of Acorn's Archimedes series.
2 Market impact
3.1 Hardware features: Models A and B
3.1.1 Export models
3.1.2 Side product
3.2 Hardware features
3.2.1 B+64 and B+128
3.3 Software and expandability
BBC BASIC built-in programming language
3.4.2 Other languages
4 Successor machines
5 Retro computing scene
5.1 Continued development and support
6 Specifications (Model A to Model B+128)
6.1 Display modes
6.2 Optional extras
7 Use in the entertainment industry
8 See also
10 External links
BBC Micro team in 2008
During the early 1980s, the
BBC started what became known as the BBC
Computer Literacy Project. The project was initiated partly in
response to an ITV documentary series The Mighty Micro, in which
Christopher Evans of the UK's National Physical Laboratory predicted
the coming microcomputer revolution and its effect on the economy,
industry, and lifestyle of the United Kingdom.
BBC wanted to base its project on a microcomputer capable of
performing various tasks which they could then demonstrate in the TV
series The Computer Programme. The list of topics included
programming, graphics, sound and music, teletext, controlling external
hardware, and artificial intelligence. It developed an ambitious
specification for a
BBC computer, and discussed the project with
several companies including Acorn Computers, Sinclair Research,
Newbury Laboratories, Tangerine Computer Systems, and Dragon Data.
The Acorn team had already been working on a successor to their
existing Atom microcomputer. Known as the Proton, it included better
graphics and a faster 2 MHz
MOS Technology 6502
MOS Technology 6502 central
processing unit. The machine was only at the design stage at the time,
and the Acorn team, including
Steve Furber and Sophie Wilson, had one
week to build a working prototype from the sketched designs. The
team worked through the night to get a working Proton together to show
the BBC. Not only was the Acorn Proton the only machine to match
the BBC's specification, it also exceeded it in nearly every
parameter. Based on the Proton prototype the
BBC signed a contract
with Acorn as early as February 1981; by June the
specifications and pricing were decided.
The keyboard of a Model B in close-up
The machine was released as the
Microcomputer on 1 December 1981,
although production problems pushed delivery of the majority of the
initial run into 1982. Nicknamed "the Beeb", it was popular
in the UK, especially in the educational market; about 80% of British
schools had a
BYTE called the
BBC Micro Model B "a no-compromise computer that has
many uses beyond self-instruction in computer technology". It called
the Tube interface "the most innovative feature" of the computer, and
concluded that "although some other British microcomputers offer more
features for a given price, none of them surpass the
BBC ... in terms
of versatility and expansion capability". As with Sinclair's ZX
Spectrum and Commodore's Commodore 64, both released later in 1982,
demand greatly exceeded supply. For some months, there were long
delays before customers received the machines they had ordered.
Efforts were made to market the machine in the United States and West
Germany. By October 1983, the US operation reported that American
schools had placed orders with it totalling $21 million. In
October 1984, while preparing a major expansion of its US dealer
network, Acorn claimed sales of 85 per cent of the computers in
British schools, and delivery of 40,000 machines per month. That
December, Acorn stated its intention to become the market leader in US
The New York Times
The New York Times considered the inclusion
of local area networking to be of prime importance to teachers.
The operation resulted in advertisements by at least one dealer in
Interface Age magazine, but ultimately the attempt failed. The
success of the machine in the UK was due largely to its acceptance as
an "educational" computer – UK schools used
BBC Micros to teach
computer literacy, information technology skills and a generation of
games programmers. Acorn became more known for its model B computer
than for its other products. Some Commonwealth countries,
including India, started their own Computer Literacy programs around
1987 and used the
BBC Micro, a clone of which was produced by
Semiconductor Complex Limited and named the SCL Unicorn.
The Model A and the Model B were priced initially at £235 and £335
respectively, but increasing almost immediately to £299 and £399 due
to increased costs. The Model B price of nearly £400 was roughly
£1200 (€1393) in 2011 prices. Acorn anticipated the total
sales to be around 12,000 units, but eventually more than 1.5 million
BBC Micros were sold.
The cost of the
BBC Models was high compared to competitors such as
ZX Spectrum and the Commodore 64, and from 1983 on Acorn attempted
to counter this by producing a simplified but largely compatible
version intended for game playing, the 32K Acorn Electron.[citation
Hardware features: Models A and B
Rear of the
BBC Micro. Ports from left to right:
UHF out, video out,
RGB, RS-423, cassette, analogue in and Econet.
The Model A had 16 KB of user RAM, while the Model B had
32 KB. A feature that the Micro shared with other 6502 computers
such as the Apple and the early Commodore models was that the RAM was
clocked twice as fast as the CPU, with alternating access given
CPU and the video display controller. This gave the BBC
Micro a fully unified memory address structure without speed
penalties. To use the
CPU at full speed (2 MHz) required the
memory system to be capable of performing four million access cycles
Hitachi was the only company, at the time, that made a
DRAM that went that fast. So for the prototype the only four 4816s in
the country got hand-carried by the rep. Most competing
microcomputers with memory-mapped display incurred
CPU speed penalties
depending on the actions of the video circuits (e.g. the Amstrad CPC
and to a lesser extent the ZX Spectrum) or kept video memory
completely separate from the
CPU address pool (e.g. the MSX).
The machine included a number of extra input/output interfaces: serial
and parallel printer ports; an
8-bit general purpose digital I/O port;
a port offering four analogue inputs, a light pen input, and switch
inputs; and an expansion connector (the "1 MHz bus") that enabled
other hardware to be connected. Extra ROMs could be fitted (four on
the PCB or sixteen with expansion hardware) and accessed via paged
Econet network interface and a disk drive interface were
available as options. All motherboards had space for the electronic
Econet was rarely fitted. Additionally, an Acorn
proprietary interface named the "Tube" allowed a second processor to
be added. Three models of second processor were offered by Acorn,
based on the 6502, Z80 and 32016 CPUs. The Tube was later used in
third-party add-ons, including a
Zilog Z80 board and hard disk drive
from Torch that allowed the
BBC machine to run
Separate pages, each with a codename, were used to control the access
to the I/O:
0xFC00 – 0xFCFF
1 MHz bus
0xFD00 – 0xFDFF
1 MHz bus / paged RAM
0xFE00 – 0xFEFF
Mapped I/O for resident hardware – video, cassette, sound,
The Tube interface allowed Acorn to use
BBC Micros with ARM CPUs as
software development machines when creating the Acorn Archimedes. This
resulted in the ARM development kit for the
BBC Micro in 1986, priced
at around £4000. From 2006 a kit with an ARM7TDMI
CPU running at
64 MHz, with as much as 64 MB of RAM, was released for the
BBC Micro and Master, using the Tube interface to upgrade the old
8-bit micros into
RISC machines. Among the software that
operated on the Tube were an enhanced version of the Elite video game
(see below) and a computer-aided design system that required a second
CPU and a 5-dimensional joystick named a "Bitstik".
The Model A and the Model B were built on the same printed circuit
board (PCB) and a Model A could be upgraded to a Model B without too
much difficulty. Users wishing to operate Model B software needed only
to add the extra RAM and the user/printer 6522 VIA (which many games
used for timers) and snip a link, a task that could be achieved
without soldering. To do a full upgrade with all the external ports
did, however, require soldering the connectors to the motherboard. The
original machines shipped with "OS 0.1", with later updates advertised
in magazines, supplied as a clip-in integrated circuit, with the last
official version being "OS 1.2". Variations in the Acorn OS exist as a
result of home-made projects and modified machines can still be bought
on internet auction sites such as eBay, as of 2011.
BBC Model A was phased out of production with the introduction of
the Electron, with chairman Chris Curry stating at the time that Acorn
"would no longer promote it" (the Model A).
BBC Micros used linear power supplies at the insistence of the
BBC's engineering specification, but these very hot-running PSUs were
soon replaced in production by switched mode units.
An apparent oversight in the manufacturing process resulted in a
significant number of Model Bs producing a constant buzzing noise from
the built-in speaker. This fault could be rectified partly by
soldering a resistor across two pads.
There were five developments of the main
BBC micro circuit board that
addressed various issues through the models production, from 'Issue 1'
through to 'Issue 7' with variants 5 and 6 not being released. The
Microcomputer Service Manual' from Acorn documented the
details of the technical changes.
Watford Electronics comments in their '32K Ram Board Manual':
Early issue BBCs (Issue 3 circuit boards and before) are notorious for
out of specification timings. If problems occur with this sort of
machine, the problem can generally be cured by the use of either a
CPU chip, or by replacing IC14 (a 74LS245) with either
another 74LS245 or the faster 74ALS245.
Advert in Interface Age magazine, November 1983, 'The BBC
Microcomputer Is Here!'
Two export models were developed: one for the US, with
speech hardware as standard; the other for West Germany. Both were
fitted with radio frequency shielding as required by the respective
countries, and they were still based on the Intel 8271 floppy drive
controller. From June 1983 the name was always spelled out completely
– "British Broadcasting Corporation
Microcomputer System" – to
avoid confusion with Brown, Boveri & Cie in international
US models included the BASIC III ROM chip, modified to accept the
American spelling of COLOR, but the height of the graphics display was
reduced to 200 scan lines to suit
NTSC TVs, severely affecting
applications written for British computers. After the failed US
marketing campaign the unwanted machines were remanufactured for the
British market and sold, resulting in a third 'UK export'
In October 1984, the
Acorn Business Computer (ABC)/Acorn Cambridge
Workstation range of machines was announced, based primarily on BBC
B+64 and B+128
Acorn introduced the Model B+ in mid-1985, increasing the total RAM to
64 KB but this had modest market effect. The extra RAM in the
BBC Micro was assigned as two blocks, a block of 20 KB
dedicated solely for screen display (so-called "Shadow" RAM) and a
block of 12 KB of 'special' Sideways RAM. The B+128 came with an
additional 64 KB (4 × 16 KB "Sideways" RAM banks) to give a
total RAM of 128 KB.
The new B+ was incapable of operating some original
BBC B programs and
games, such as, for example, the very popular Castle Quest. A
particular problem was the replacement of the Intel 8271 floppy disk
controller with the
Western Digital 1770 – not only was the new
controller mapped to different addresses, it was fundamentally
incompatible and the 8271 emulators that existed were necessarily
imperfect for all but basic operation. Software that used copy
protection techniques involving direct access to the controller,
simply would not operate on the new system. Acorn attempted to
alleviate this, starting with version 2.20 of the 1770 DFS, via an
8271-backward- compatible Ctrl+Z+Break option.
There was also a long-running problem late in the B/B+'s commercial
life infamous amongst B+ owners, when
Superior Software released
Repton Infinity, which refused to operate on the B+. A series of
unsuccessful replacements were issued before one compatible with both
was finally released.
During 1986, Acorn followed up with the
BBC Master, which offered
memory sizes from 128 KB and many other refinements which
improved on the 1981 original. It had essentially the same 6502-based
BBC architecture, with many of the upgrades that the original design
had intentionally made possible (extra ROM software, extra paged RAM,
second processors) now included on the circuit board as internal
Software and expandability
Elite (Acornsoft, 1984). The unusual game screen used two display
modes at once, to show both detail and colour.
BBC Micro platform amassed a large software base of both games and
educational programs for its two main uses as a home and educational
computer. Notable examples of each include the original release of
Elite and Granny's Garden. Programming languages and some
applications were supplied on ROM chips to be installed on the
motherboard. These loaded instantly and left the RAM free for programs
Although appropriate content was little-supported by television
broadcasters, telesoftware could be downloaded via the optional
Teletext Adapter and the third-party teletext adaptors that emerged.
The built-in operating system, Acorn MOS, provided an extensive
interface with all standard peripherals, ROM-based software and the
screen. Features private to some versions of BASIC, like vector
graphics, keyboard macros, cursor-based editing, sound queues and
envelopes, were placed in the MOS ROM and made available to any
BBC BASIC itself, being in a separate ROM, could be
replaced with any equivalent language.
BASIC, other languages and utility ROM chips resided in any of four
16 KB paged ROM sockets, with OS support for sixteen sockets via
expansion hardware. The five (total) sockets were located partially
obscured under the keyboard, with the leftmost socket hard-wired for
the OS. While the original usage for the perforated panel on the left
of the keyboard was for a Serial ROM or Speech ROM, a ZIF socket or
edgecard connector could be installed in that location instead. The
socket could be connected to one of the empty Sideways/PagedROM
sockets via a header cable. The paged ROM system was essentially
modular. A language-independent system of star commands, prefixed with
an asterisk, provided the ability to select a language (for example
*BASIC, *PASCAL), a filing system (*TAPE, *DISC), change settings
(*FX, *OPT) or carry out ROM-supplied tasks (*COPY, *BACKUP) from the
command line. The MOS recognised a handful of built-in commands, and
polled the paged ROMs in descending order for service otherwise; if
none of them claimed the command then the OS returned a Bad command
error. Connecting an external EPROM programmer, one could write
extensive programs, copy to programmable ROM (PROM) or EPROM, then
invoke them without taxing user memory.
Main article: Sideways address space
Not all ROMs offered star commands (ROMs containing data files, for
instance), but any ROM could "hook" into certain vectors to enhance
the system's functionality. Often the ROM was a device driver for mass
storage combined with a filing system, starting with Acorn's 1982 Disc
Filing System whose
API became the de facto standard for floppy disc
access. The Acorn
Graphics Extension ROM (GXR) expanded the VDU
routines to draw geometric shapes, flood fills and sprites. During
Micro Power designed and marketed a Basic Extension ROM,
introducing statements such as WHILE, ENDWHILE, CASE, WHEN, OTHERWISE,
and ENDCASE, as well as direct mode commands including VERIFY.
Acorn strongly discouraged programmers from directly accessing the
system variables and hardware, favouring official system calls.
This was ostensibly to make sure programs kept working when migrated
to coprocessors that utilised the Tube interface, but it also made BBC
Micro software more portable across the Acorn range. Whereas
untrappable PEEKs and POKEs were commonly used by other computers to
reach the system elements, programs in either machine code or BBC
BASIC would instead pass parameters to an operating system routine. In
this way the MOS could translate the request for the local machine or
send it across the Tube interface, as direct access was impossible
from the coprocessor. Published programs largely conformed to the API
except for games, which routinely engaged with the hardware for
greater speed, and thus required a particular Acorn model.
As the early
BBC Micros had ample I/O allowing machines to be
interconnected, and as many schools and universities employed the
Econet networks, numerous networked multiplayer games were
created. With the exception of a tank game, Bolo, few became popular,
in no small measure due to the limited number of machines aggregated
in one place. A relatively late but well documented example can be
found in a dissertation based on a ringed
In line with its ethos of expandability Acorn produced its own range
of peripherals for the
BBC Micro, including:
Floppy drive interface upgrade
Floppy drives (single and double)
Econet networking upgrade
Winchester disk system
6502 Second Processor
Z80 Second processor (with
CP/M and business software suite)
32016 Second processor
ARM Evaluation System
Music 500 synthesiser
BBC Turtle (robot)
IEEE 488 Interface
Other manufactures also produced an abundance of add-on hardware, some
the most common being:
BBC BASIC built-in programming language
BASIC prompt after switch-on or hard reset.
The built-in ROM-resident
BBC BASIC programming language interpreter
realised the system's educational emphasis and was key to its success;
not only was it the most comprehensive BASIC compared to other
contemporary implementations but it ran very efficiently and was
therefore fast. Advanced programs could be written without resorting
to non-structured programming or machine code (necessary with many
competing computers). Should one want or need to do some assembly
BBC BASIC featured a built-in assembler that allowed a
very easy mixture of
BBC BASIC and assembler for whatever processor
BBC BASIC was operating on.
BBC Micro was released, many competing home computers used
Microsoft BASIC, or variants typically designed to resemble it.
Compared to Microsoft BASIC,
BBC BASIC featured IF…THEN…ELSE,
REPEAT…UNTIL, named procedures and functions, but retained
GOSUB for compatibility. It also supported high-resolution graphics,
four-channel sound, pointer-based memory access (borrowed from BCPL)
and rudimentary macro assembly. Long variable names were accepted and
distinguished completely, not just by the first two characters.
Acorn had made a point of not just supporting
BBC Basic but a number
of contemporary languages, some of which were supplied as ROM chips to
fit the spare 'Sideways-ROM' sockets on the motherboard. Other
languages were supplied on tape or disk based.
Programming Languages from Acorn:
ISO Pascal (2× 16 KB ROM + floppy disk)
S-Pascal (disk or tape)
BCPL (ROM plus further optional disk based modules)
Forth (16 KB ROM)
LISP (disk,tape or ROM)
Logo (2× 16 KB ROM)
Graphics (disk or tape)
Micro-PROLOG (16 KB ROM)
COMAL (16 KB ROM)
Microfocus CIS COBOL (running under
CP/M on floppy disks via the Z80
Main article: Acorn Archimedes
Acorn produced their own
32-bit Reduced Instruction Set (RISC) CPU
during 1985, the ARM1. Furber composed a reference model of the
processor on the
BBC Micro with 808 lines of BASIC, and ARM Holdings
retains copies of the code for intellectual property purposes. The
first prototype ARM platforms, the ARM Evaluation System and the A500
workstation, functioned as second processors attached to the BBC
Micro's Tube interface. Acorn staff developed the A500's operating
system in situ through the Tube until, one by one, the on-board I/O
ports were enabled and the A500 ran as a stand-alone computer.
With an upgraded processor this was eventually released during 1987 as
four models in the Archimedes series, the lower-specified two models
(512 KB and 1 MB) continuing the
with the distinctive red function keys. Although the Archimedes
ultimately was not a major success, the ARM family of processors has
become the dominant processor architecture in mobile embedded consumer
devices, particularly mobile telephones.
Acorn's last BBC-related model, the
BBC A3000, was released in 1989.
It was essentially a 1 MB Archimedes back in a single case form
Retro computing scene
Hermann Hauser playing a game on a Master in 2012
As of 2005, thanks to its ready expandability and I/O functions, there
are still numbers of
BBC Micros in use, and a retrocomputing community
of dedicated users finding new tasks for the old hardware. They still
survive in a few interactive displays in museums across the United
Kingdom, and the
Jodrell Bank observatory was reported to be still
BBC Micro to steer its 42 ft radio telescope during
2004. The Archimedes came with 65Arthur, an emulator which BYTE
stated "lets many programs for the
BBC Micro run"; other emulators
exist for many operating systems.
Clockwise from top left: Hermann Hauser, Andy Hopper, Christopher
Curry, Sophie Wilson, David Allen, Chris Serle, David Kitson, Chris
Steve Furber at the
BBC Micro 30th anniversary in 2012
In March 2008, the creators of the
BBC Micro met at the Science Museum
in London. There was to be an exhibition about the computer and its
legacy during 2009.
National Museum of Computing
National Museum of Computing at
Bletchley Park uses
as part of a scheme to educate school children about computer
In March 2012, the
BBC and Acorn teams responsible for the
and Computer Literacy Project met for a 30th anniversary party,
entitled "Beeb@30". This was held at ARM's offices in Cambridge and
was co-hosted by the Centre for Computing History.
Continued development and support
Long after the "venerable old Beeb" was superseded, additional
hardware and software has been developed. Such developments have
included Sprow's 1999 zip compression utility and a ROM
Y2K bugfix for
There are also a number of websites still supporting both hardware and
software development for the
BBC micros and Acorn in general.
Specifications (Model A to Model B+128)
MOS Technology 6502A at 2 MHz
Rockwell Semiconductor 6512A at 2 MHz
64 KB composed of 32 KB standard memory, 20 KB video
(Shadow) memory and 12 KB extended (special Sideways) memory.
128 KB composed of 32 KB standard memory, 20 KB video
(Shadow) memory and 76 KB extended (Sideways) memory.
32 KB of ROM composed of a 16 KB MOS (Machine Operating
System) chip, and 16 KB read-only paged space defaulting to the
BBC BASIC chip. Four paged 16 KB ROM sockets standard, expandable
48 KB of ROM composed of 16 KB MOS, 16 KB DFS, and
16 KB read-only paged space defaulting to the
Full-travel keyboard with a top row of ten red-orange function keys
ƒ0–ƒ9. These generated text semigraphics when pressed with CTRL or
SHIFT, and could be programmed with keyboard macros. The arrow keys
and BREAK could also serve as function keys. Links on the keyboard PCB
allowed users to select the behaviour of Shift+Break, and Display Mode
As Model B except
RGB (Optional upgrade, soldering required).
6-pin DIN digital
RGB connector +5 V/0 V, 1 V p-p
composite colour or monochrome video (link S39) and built-in
As Model B, but Modes 0, 1, 2, and 3 not available due to lack of
Configurable graphics in Modes 0–6 (see table below) based on the
Motorola 6845 CRT controller or Mode 7, a special
Teletext mode, based
Teletext chip and only taking 1 KB of RAM.
Four independent sound channels (one noise and three melodic) using
Texas Instruments SN76489
Texas Instruments SN76489 sound chip. Phoneme-based speech
synthesis using the
TMS5220 with a custom Acorn ROM
(the "PHROM", a TMS6100) of Kenneth Kendall's voice (optional).
Tape interface (with a relay operated motor control, controlled via 2
pins on a circular 7-pin DIN connector), using the CUTS [Computer
Users' Tape Standard] variation of the
Kansas City standard
Kansas City standard data
encoding scheme operating at 1200 or 300 baud.
Optional floppy disk interface based initially on the Intel 8271
controller and later on the WD1770, also requiring the installation of
the DFS (disk filing system) ROM (and of soldered connector on Model
5.25" floppy drive usually used) – Densities: Single-Sided,
Single Density[SS/SD], Single-Sided, Double-Density[SS/DD],
Double-Sided, Single-Density[DS/SD] and Double-Sided,
Floppy disk controller based on the
and DFS ROM as standard (except ANB51, ANB52).
None (lack of memory).
Additional ADFS ROM required, external drive unit connected to the 1
MHz Bus interface. (Winchester Hard disc drives with 5 MB, 10 MB
or 20 MB capacities. Maximum of 512 MB per drive, up to four
Optional upgrade, soldering required.
RS-423 serial port.
Optional upgrade, soldering required.
26-pin IDC Centronics-compatible parallel port.
Optional upgrade, soldering required.
20-pin IDC "user port" with 8 general purpose digital I/O pins and two
special/trigger sensitive digital pins used for control purposes (for
e.g. a turtle when using the Logo programming language).
Optional upgrade, soldering required.
DA15 socket with four 8/12 bit analogue inputs based on µPD7002 IC
(suitable for two joysticks), two inputs suitable for pushbuttons and
an input for a light pen.
1 MHz Bus
Optional upgrade, soldering required.
34-pin IDC connector for generic expansion on a "daisy-chain" (used
for connecting hard disks, sound synthesisers etc.).
Optional upgrade, soldering required.
40-pin IDC connector for external second CPU. Options included a
second 6502, a Zilog Z80, the ARM Evaluation System, or a National
Semiconductor 32016 (the latter was either branded "
System – 32016 Second Processor" or "Acorn Computer – Cambridge
Co-Processor"), other vendors added 6809, 6800, 68000 and 68008. A
10 MHz 80186 co-processor from a
BBC Master can be connected
through a co-processor adapter to a
BBC Micro, thus enjoying a limited
degree of PC compatibility.
Network (Optional extra)
Econet large-scale low-cost networking system – around
100 kbit/s using the
Motorola 68B54 (standard on US model).
Secondary power output
Power supply for external disk drives, 6-pin, top to bottom, left to
0 V, 0 V
+5 V DC @ 1.25 A,
+12 V DC @ 1.25 A,
NC, −5 V DC @75 mA,
IBM PC with the contemporary Color
Graphics Adapter, the
video output of the
BBC Micro could be switched by software between a
number of display modes. These varied between 20 and 40-column text
suitable for a domestic TV, to 80-column text best viewed with a
high-quality RGB-connected monitor (The 80-column mode was often too
blurred to view when using a domestic TV via the
UHF output). The
variety of modes offered applications a flexible compromise between
colour depth, resolution and memory economy. In the first models, the
OS and applications were left with the RAM left over from the display
Mode 7 was a
Teletext mode, extremely economical on memory and an
original requirement due to the BBC's own use of broadcast teletext
(Ceefax). It also made the computer useful as a
Prestel terminal. The
teletext characters were generated on board, for use with monitors and
TV sets without a
Teletext receiver. Train time displays at UK
stations were driven by
BBC Master computers in this mode until around
the late 1990s. Mode 7 used only 1 KB for video RAM
by storing each character as its
ASCII code, rather than its bitmap
image as was needed for the other modes.
Modes 0 to 6 (the 'ASCII' modes) could display colours from a logical
palette of sixteen: the eight basic colours at the vertices of the RGB
colour cube and eight flashing colours made by alternating the basic
colour with its inverse. The palette could be freely reprogrammed
without touching display memory. Modes 3 and 6 were special text-only
modes that used less RAM by reducing the number of text rows and
inserting blank scan lines below each row. Mode 6 was the smallest,
allocating 8 KB as video memory. Modes 0 to 6 could show diacritics
and other user defined characters. All modes except 7 supported
bitmapped graphics, but graphics commands such as DRAW and PLOT had no
effect in the text-only modes.
BBC B+ and the later Master provided 'shadow modes', where the
1–20 KB frame buffer was stored in an alternative RAM bank,
freeing the main memory for user programs. This feature was requested
by setting bit 7 of the mode variable, i.e. by requesting modes
80 × 32
640 × 256
40 × 32
320 × 256
20 × 32
160 × 256
80 × 25
640 × 200
40 × 32
320 × 256
20 × 32
160 × 256
40 × 25
320 × 200
40 × 25
480 × 500
A speech synthesis upgrade based on the
Texas Instruments TMS5220
featured sampled phonemes spoken by
BBC newscaster Kenneth Kendall.
The speech system was standard on the US model where it had an
American vocabulary. Elsewhere it sold poorly and was eventually
largely replaced by Superior Software's software-based synthesiser
using the standard sound hardware.
The speech upgrade also added two empty sockets next to the keyboard
intended to take 16 KB serial ROM cartridges containing either
extra speech phoneme data (in addition to the default speech ROM
fitted to the motherboard), or general software accessed through the
ROM Filing System. The original plan was that some games would be
released on cartridges, but due to the limited sales of the speech
upgrade, little or no software was ever produced for these sockets.
The cut-out space next to the keyboard (nicknamed the "ashtray") was
more commonly used to install other upgrades, such as a ZIF socket for
conventional paged ROMs.
Use in the entertainment industry
BBC Domesday Project, a pioneering multimedia experiment, was
based on a modified version of the
BBC Micro's successor, the BBC
Vince Clarke of the British synth pop bands Depeche Mode,
Erasure used a
BBC Micro (and later a
BBC Master) with the
UMI music sequencer to compose many hits. In music videos from the
1980s featuring Vince Clarke, a
BBC Micro is often present or provides
text and graphics such as a clip for Erasure's "Oh L'Amour". The
musical group Queen used the UMI Music Sequencer on their record A
Kind of Magic. The UMI is also mentioned in the CD booklet. Other
bands who have used the Beeb for making music are
A-ha and the reggae
band Steel Pulse. Paul Ridout is credited as "UMI programmer" on Cars'
bassist/vocalist Benjamin Orr's 1986 solo album, The Lace. Black Uhuru
used the Envelope Generator from SYSTEM software (Sheffield) running
BBC Micro, to create some of the electro-dub sounds on Try It
(Anthem album 1983).
BBC Micro was used extensively to provide graphics and sound
effects for many early 1980s
BBC TV shows. These included, notably,
series 3 and 4 of The Adventure Game; the children's quiz game
"First Class" (where the onscreen scoreboard was provided by a BBC
Micro nicknamed "Eugene"); and numerous 1980s episodes of Doctor Who
including "Castrovalva", "The Five Doctors", and "The Twin Dilemma".
BBC Computer Literacy Project 2012
Micro Bit – modern successor to the project
Micro Men -
BBC documentary drama
Micro Live –
BBC television programme
Making the Most of the Micro
Making the Most of the Micro –
BBC television programme
BEEBUG – user group magazine
(BBC) Acorn User
The Micro User
The Micro User (also known as Acorn Computing)
^ Hachman, Mark (2002). "ARM Cores Climb into 3G Territory".
^ Turley, Jim (2002). "The Two Percent Solution".
^ a b c d Hormby, Thomas (8 February 2007). "Acorn and the
From education to obscurity". Low End Mac. Archived from the original
on 3 March 2007. Retrieved 1 March 2007.
^ Laing, Gordon (22 March 2004). "Retro computing". Personal Computer
World. Archived from the original on 20 August 2012. Retrieved 10
^ Collins, Barry (7 August 2006). "
BBC Basic: the people's language".
PC Pro. Archived from the original on 10 February 2007. Retrieved 7
^ a b c Smith, Tony (30 November 2011). "The
BBC Micro turns 30". The
Register Hardware. Retrieved 12 December 2011.
Microcomputer and me, 30 years down the line".
BBC News. 1 December 2011. Retrieved 13 December 2011.
^ a b "'Beeb' creators reunite at museum".
BBC News. 20 March 2008.
Archived from the original on 23 March 2008. Retrieved 23 March
^ Vasko, Tibor; Dicheva, Darina (September 1986). "Educational
policies: an international review" (PDF). Austria: International
Institute for Applied Systems Analysis: 7. Retrieved 12 December
^ a b McClelland, David (18 March 2011). "How a
BBC Micro shaped the
course of GeekDad's life". Wired. Archived from the original on 30
^ Williams, Gregg (January 1983). "Microcomputer, British Style / The
Personal Computer World
Personal Computer World Show". BYTE. p. 40. Retrieved 19
^ Feder, Barnaby J. (27 February 1984). "British race is on in
microcomputers". The New York Times. New York. Retrieved 12 December
2011. Sales neared $60 million in the second half of last year as
efforts began to sell to schools in the United States and
^ "Acorn Computer Makes U.S. Debut". The New York Times. 7 October
1983. Retrieved 12 December 2011.
Acorn Computers Ltd., which
dominates the educational computer market in Britain, introduced its
BBC microcomputer in the United States yesterday and said it had
already received $21 million in orders from American schools. [...]
the Acorn Computer Corporation, the British company's United States
^ Caruso, Denise (8 October 1984). "Acorn plucks former Apple reps".
InfoWorld. CW Communications (via Google Books). 6 (41): 14.
^ a b Lewis, Peter H. (18 December 1984). "Peripherals; The British
are Coming". The New York Times. New York. Retrieved 12 December 2011.
At a consumer electronics show in London last week, a company official
said Acorn intends to rectify the situation by becoming the
best-selling educational computer in America. [...] Most important to
teachers, the Acorn is already set up for local area networking,
allowing all computers in a classroom to be linked together.
^ Edwards, Benj (17 May 2010). "[ Retro Scan of the Week ] The BBC
Microcomputer". Vintage Computing and Gaming. Retrieved 23 May 2011.
This scan of an American
Microcomputer ad [...]
^ Sadauskas, Andrew (27 July 2012). "
BBC Micro B lives on: Strong
growth for ARM after increased tablet and smartphone use".
SmartCompany. Retrieved 7 August 2012.
^ Tank, Andrew (10 April 1986). "India's Schoolchildren Have Got
Class". Computer Weekly. General Reference Center Gold.
^ Keval J. Kumar (1987). "Media education and computer literacy in
India: The need for an integrated 'compunication". International
Communication Gazette. 40 (3): 183–202.
^ "SCL Unicorn". computinghistory.org.uk.
^ a b "
BBC Micro – Review". Computing Today. March 1982. Retrieved
12 December 2011.
^ Dunn, John E (1 December 2011). "Geeks rejoice as
celebrates 30-year anniversary". Techworld. Retrieved 4 March
BBC Micro celebrates thirtieth anniversary". TechCentral.ie. PC
Live!. 2 December 2011. Archived from the original on 17 February
2013. Retrieved 4 March 2012.
^ "Home computing pioneer honoured".
BBC News. 29 December 2007.
Retrieved 26 April 2010.
^ Stirling, Mike (21 August 2011). "
BBC Micro on an FPGA". Retrieved
11 June 2012.
^ Fairbairn, Douglas (31 January 2012). "Oral History of Sophie
Wilson" (PDF). Retrieved 2 February 2016.
Microcomputer Service Manual]
^ The start of the revival – The ARM and the Archimedes (1986 to
BBC Micro ARM7 co-processor available –
RISC OS News, Software and
^ Sprow's webpages – cyber doctor for poorly beebs
Watford Electronics 32K Ram Board Manual
^ Scholten, Wouter (17 June 2007). "USA model
BBC micro". Retrieved 28
^ Whytehead, Chris (9 November 2007). "Chris's Acorns: German BBC
Microcomputer Model B". Archived from the original on 21 February
2010. Retrieved 28 March 2008.
^ "Name changes for the worse". The Micro User. Stockport, UK:
Database Publications. 1 (4): 112. June 1983.
^ Bray, Andrew C.; Dickens, Adrian C.; Holmes, Mark A. (1983).
"Appendix G". The Advanced User Guide for the
(zipped PDF). Cambridge, UK: Cambridge
p. 512. ISBN 0-946827-00-1. Retrieved 28 March 2008.
^ "US Issue 1 BBC". Retrieved 23 May 2011. These machines were
originally manufactured for export to America. Having now shipped them
^ Whytehead, Chris. "Chris's Acorns: US
for UK)". Archived from the original on 17 February 2010. Retrieved 28
Microcomputer System User Guide (PDF). British Broadcasting
Corporation. October 1984. p. 422. Retrieved 13 December
^ Kevin Edwards (January 1986). "Inside the 8271 – how your DFS
really functions". The Micro User. Stockport, UK: Database
Publications. 3 (11): 228. ISSN 0265-4040.
^ "Support Group Application Note No. 023" (PDF). Issue 1. Acorn
Computers. 9 July 1992. Retrieved 12 December 2011. [permanent
^ "Remembering the
BBC News. 20 March 2008. Retrieved 30
Microcomputer User Guide, chapter 42, pp. 418–441.
The light pen, 1 MHz bus and user port were supported by generic
memory-mapped I/O calls (OS
BYTE 146–151), and
could be printed through OSWRCH like normal text. The Archimedes and
its Interface Podule successfully emulated
Teletext and the user port
through these calls.
^ "Section – Language Extension". A & B Computing. 1 Golden
Square, London: Argus Specialist Publications: 27–29. February
^ Coll, John (1982). The
Microcomputer User Guide. London: British
Broadcasting Corporation. pp. 450, 468.
Sinclair Research Ltd,
ZX Spectrum BASIC programming, chapters
^ Stuart Cheshire (1989-05-19). "An Experiment in Real-Time
Networking". Archived from the original on 2017-03-18. Retrieved
^ Furber, Steve (speaker); Fitzpatrick, Jason (producer, director) (22
Talk – Acorn World – 13-09-2009
(Podcast). Haverhill, Suffolk, UK: Centre for Computing History. Event
occurs at 25:35, 38:20. It turns out [the ARM reference model] is
quite important because there are some interesting patent defence
cases that depend to some significant extent on this information.
[...] I wrote the
BBC BASIC reference model, [...] and the complete
thing is 808 lines of
BBC BASIC, and that's the complete
processor. The Acorn World exhibition was held in Huddersfield.
^ Whytehead, Chris. "Chris's Acorns: Acorn A500 (prototype)". Chris's
Acorns. Retrieved 10 February 2012.
^ Libbenga, Jan (19 January 2004). "My PC is older than yours".
Letters. The Register. Retrieved 13 December 2011.
^ Pountain, Dick (October 1987). "The Archimedes A310". BYTE.
p. 125. Retrieved 4 August 2014.
^ Ward, Mark (25 August 2010). "Tech Know:
BBC Micros used in retro
BBC News. Archived from the original on 26 August
2010. Retrieved 25 August 2010.
^ a b "Internet portal launched".
Acorn User (215). December 1999.
p. 7. Retrieved 16 August 2013.
^ Whytehead, Chris. "Chris's Acorns:
BBC Microcomputers". Retrieved 30
^ Wolstenholme, Ian (1 September 2010). "Beebmaster – Beebhelp –
Acorn Serial Numbers". Retrieved 30 November 2010.
^ Burton, Robin (May 1993). "512 Forum". Beebug. 12 (1):
^ Reference Data Sheet:SAA5050 Series, Teltext Character Generator,
July 1982, Mullard.
^ "Erasure's Big Hit". Acorn User. 1 June 1988.
The Adventure Game
The Adventure Game S03E03 , Part 3 , Adam Tandy , Sandra Dickinson
Chris Serle - YouTube". 2010-06-11. Retrieved 2016-06-24.
Wikimedia Commons has media related to
BBC Micro at Curlie (based on DMOZ)
BBC Micro Wiki
Acorn and the
BBC Micro: From education to obscurity (archived)
BBC Micro @ The Centre for Computing History
BBC Micro connected to the Internet converting RSS headline feeds from
BBC News site into audio
Video of a
BBC computer show from 1985
Microcomputer User Guide
BBC Computer Literacy Project
Model A, B and B+
Archimedes range and A3000
TV programmes / services
Now the Chips are Down
The Computer Programme
Making the Most of the Micro
Telesoftware via Ceefax
Advanced Disc Filing System
Disc Filing System
Doctor Who and the Warlord
Doctor Who: The First Adventure
CST (Cambridge Systems Technology)
Pace Micro Technology
6502 Second Processor
Z80 Second Processor
BBC Domesday Project
Acorn Computers, derivatives, clones and compatibles
Systems 2 to 5
BBC Micro (aka Proton)
BeagleBoard-xM in Kiste)
32-bit dev boards