BBC Micro

The BBC Micro was born from a television programme. When the BBC planned a computer literacy series, they needed a machine to recommend. Acorn Computers won the contract, and their BBC Micro became the standard in British schools. More expensive than the Spectrum, better built, with superior BASIC—it educated a generation even if it never dominated bedrooms.

Fast facts

Manufacturer: Acorn Computers.
Launch: December 1981.
Price: £299 (Model A), £399 (Model B).
CPU: MOS 6502A at 2 MHz.
RAM: 16KB (Model A), 32KB (Model B).
Graphics: 8 display modes, up to 640×256 or 160×256 with more colours.
Sound: Texas Instruments SN76489, 3 channels plus noise.
BBC connection: tied to BBC’s Computer Literacy Project.

When it actually arrived

The machine is dated 1981 and that holds — the name appears in the press that year. But the shape of the coverage says the BBC Micro did not become a real presence until 1982, and it says so sharply: 14 pages in 1981, then 497 in 1982 and 2,188 in 1983.

That gap is the machine’s own production history showing up in the trade press. It was announced into a demand it could not meet, and the writing follows the deliveries rather than the announcement.

By the summer of 1983 the price had settled unevenly. One dealer page in Your Computer that July lists “BBC MICRO (A) £299.00 (B) £399.00”; another in the same issue asks £349 for a 32K Model A and the same £399 for the Model B. The Model B is the fixed point every dealer agrees on; the Model A is not, which is what happens to a model people are being upgraded out of.

The BBC Computer Literacy Project

The British Broadcasting Corporation wanted to teach computing:

TV series explaining concepts
A recommended computer for viewers
Acorn beat Sinclair for the contract
The “BBC Micro” branding gave instant credibility
Schools adopted it widely

The display modes are a memory budget

“Eight display modes” reads as generosity. On a 32K machine it is a menu of prices, and the Advanced User Guide prints the tariff: HIMEM, the start of screen memory, “has the value &3000 for modes 0, 1, and 2; &4000 for mode 3; &5800 for modes 4 and 5; &6000 for mode 6; and &7C00 for mode 7 (teletext)”.

RAM ends at &7FFF and user workspace starts at &E00, so each of those addresses sets both what the screen takes and what is left between the two:

Mode	Screen starts	Screen costs	Room for your program
0, 1, 2	&3000	20K	8.5K
3	&4000	16K	12.5K
4, 5	&5800	10K	18.5K
6	&6000	8K	20.5K
7	&7C00	1K	27.5K

Mode 0’s 640×256 display consumes nearly two thirds of a Model B. Mode 7 costs a twentieth of that, because it is not a bitmap at all — it is teletext, a grid of character codes rendered by a dedicated chip.

This is the practical reason so much BBC software looks like teletext. It is rarely an aesthetic decision. A program that wants room to be a program takes Mode 7 and has 27.5K to work in; the same program in Mode 0 has 8.5K and a beautiful empty screen.

⚠ Those last figures are ceilings. The guide notes that OSHWM “may be raised by font explosion, or by paged ROMs taking workspace”, so a real machine with sideways ROMs fitted has less.

The Tube inverts the machine

The entry above lists the Tube as “expansion”, which undersells what it does. A second processor on the Tube does not assist the BBC Micro. It replaces it, and the machine that was your computer becomes a peripheral controller for the one that now is.

The New Advanced User Guide describes the arrangement in the operating system’s own terms: “most of these second processor operating system routines involve passing the request across the Tube to the i/o processor where the operating system proper performs” the work. The BBC’s own 6502 is, in the documentation’s vocabulary, the i/o processor. Your application runs elsewhere — on a Z80, a 32016, or an ARM — and talks to the keyboard and the disc through the machine it is plugged into.

Every other system in this Vault adds co-processors to take work off the CPU. Acorn built a socket that lets you replace the CPU and keep everything else, which is how a machine sold for schools in 1981 ended up as the development host for the first ARM.

Technical excellence

The BBC Micro was well-engineered:

BBC BASIC: arguably the best 8-bit BASIC, with named procedures and inline assembler.
Expansion: Tube interface allowed second processors (Z80, 6502, 32016, ARM).
Networking: Econet for school computer labs.
Build quality: solid keyboard, reliable hardware.
Documentation: excellent manuals and programming guides.

Educational dominance

British schools standardised on BBC Micros:

Government funding: subsidised purchases for education.
Curriculum integration: programming taught using BBC BASIC.
Networking: Econet connected classroom machines.
Longevity: remained in schools well into the 1990s.

The gaming library

Despite educational focus, games existed:

Elite (1984): revolutionary space trading game.
Chuckie Egg: platform classic.
Repton: puzzle-platformer series.
Citadel: atmospheric adventure.

Fewer games than Spectrum or C64, but a devoted following.

The ARM legacy

Acorn’s most lasting contribution came from BBC Micro development:

Acorn RISC Machine: designed for BBC Micro successor.
ARM processor: became the world’s most-used CPU architecture.
Mobile revolution: ARM powers virtually every smartphone.
From classroom to pocket: BBC Micro’s descendants are everywhere.

Legacy

The BBC Micro proved computers belonged in education. Its BASIC taught clean programming habits. Its networking pioneered computer labs. And its ARM processor architecture, born from the need for a faster BBC Micro, now runs billions of devices.

The educational powerhouse