November 5, 2019 7 min to read

The BBC Micro

Category : Computers

Ask any computer programmer from the UK over thirty where they got their first experience of computers, and I’ll bet you that most would say one thing: the BBC Micro. This pioneering computer was where a generation of programmers and hackers cut their computing teeth, creating games like Elite and the first shareware and open source computer titles.

The BBC Micro / Wikipedia

The BBC Micro was created by the British Broadcasting Corporation (BBC) the main broadcaster in the UK. Think PBS, but without the pledge drives: the organization was mostly funded through a TV license that is still required to watch TV in the UK. As part of this, the BBC was expected to offer educational content, and the BBC Micro was part of a program called the BBC Computer Literacy Project, designed to help the UK become more computer savvy in those early days of the computer revolution.

The BBC asked a number of companies to come up with a design for a home computer to go with this project, which would be focussed on education, expandability and programming. The winning design was built by the UK company Acorn, a revised version of their Acorn Atom computer. The proposed BBC Micro was built around a Motorola 6502 processor running at 2MHz, with either 16 or 32 kB of RAM. Unlike the contemporary Sinclair ZX Spectrum, the BBC Micro would offer a range of inputs and outputs, be expandable and would work with a standard TV. It would also come with a programming language built in (a version of the simple programming language BASIC), so users could jump straight in and start programming right away, without needing to buy extra hardware or software. In short, it would put the power of computing and programming into people’s homes for the first time in a simple, one-stop package.

The BBC Micro, right out of the box / Classic Acorn

The BBC Micro went on sale in late 1981, and was an immediate hit. At £299/ $455 for the 16KB model called the Model A and £399 / $600 for the 32KB Model B, it was an expensive computer, compared to other models like its contemporaries the Sinclair ZX81 or the Commodore VIC-20. The decision to pitch it higher and play up the educational angle proved to be a wise one: people snapped the new computer up, and the sales were much higher than the estimates. “When the BBC first came talking about the contract their estimate was that maybe 12,000 would be sold,” Steve Furber, one of the designers told BBC News on the 30th anniversary of the launch. Instead, the small company eventually sold over 1.5 million of them.

One of those was sold to me. With my parent’s help, I bought one after the Sinclair ZX Spectrum I had initially pre-ordered was delayed for several months, and I never looked back. While the ZX Spectrum had a notoriously failure-prone membrane keyboard, the BBC Micro had a gorgeously clicky full-sized keyboard that could handle the over-enthusiatic bashing of a teenage wannabe-hacker like me. Soon, games started appearing for the new computer, and I spent many happy hours cruising the galaxy and shooting pirates in the revolutionary 3D space trading game Elite (which is now being reborn through a successful Kickstarter campaign)

The baked-in BBC BASIC meant that you could start programming immediately without requiring extra software or hardware, which meant that any store that displayed the computer was immediately overwhelmed by kids typing in BASIC programs like this:

20 GOTO 10

(spoilers for those who don’t know BASIC; you get a screen full of scrolling text that reads YOU SMELL, until you hit escape to stop it.)

It is perhaps hard for those who have grown up with ubiquitous computing power to understand how revolutionary it was to have a computer in your home. Especially one that was designed to hack: the BBC Micro had a very open architecture that encouraged people to get into the guts of the machine and tinker, with pretty much every signal from inside the machine available on the expansion port and easily addressable serial and parallel ports. A huge selection of accessories were available, including the then-radical idea of a second CPU expansion (either a second 6502 or a Zilog Z80 processor) that could either run a different OS, or increase the computing power of the system. Famously, one of the incentives to buy this was the improved graphics quality of games like Elite with the second processor, a harbinger of modern graphics cards that use dedicated processors to create gaming and other graphics.

Rather than using expensive floppy disk drives, the BBC Micro stored programs on cassette tapes, coding them into an audio signal that could then be re-loaded when the tape was played back. Although it was a cheap solution, this was one of the weaknesses of the system: the process was very dependent on the quality of the cassette recorder, and there were few things more frustrating than typing in a long program and saving it to tape, only to have the program refuse to reload later. Professional games got around the slow speed of loading from cassette tape by adding intro music and animation that played while the game was loading.

After the success of the BBC Micro, Acorn produced several more iterations, such as the Model B+ and the 1986 BBC Master before their partnership with the BBC ended. Subsequently, and they produced the Acorn Archimedes, which was the first home computer to use the RISC (Reduced Instruction Set Coding) architecture that Acorn had developed , where the processor sacrifices more sophisticated processor instructions for the speed and efficiency of a few simple ones. This power-sipping approach later found a home in mobile devices like cell phones and tablets, most of which are based on later generations of the RISC architecture and approach that are licensed from ARM (Acorn RISC Machine or Advanced RISC Machine), the corporate offspring of Acorn. This is why most modern cell phones (including those from Samsung) have a legalistic shout-out to ARM somewhere deep in the technical specs: an interesting call out to the brains behind the BBC Micro.

The BBC Micro design team in 2008 / Computer History Museum

The BBC Micro is far from dead and buried, though. The robustness of the keyboard and design mean that the computers were still in use in many UK schools well into the 1990s, and the hacker community is still active, producing hacks that add things like USB portssolid state storage and ethernet ports to connect the aging computer to the Internet.

Perhaps the device that has best captured the spirit of the BBC Micro recently is the wildly successful Raspberry PI. This simple computer on a board has the same aims as the BBC Micro: it is simple to get into, expandable and encourages kids to get into the guts and figure out how things work. It manages one thing that the BBC Micro didn’t: at $45, it is cheap. The motivation of the charity behind the computer is that “We want owning a truly personal computer to be normal for children”: a laudable aim that they are getting some way towards achieving.

Personally, I am glad that it is cheap: I don’t want anyone else to have my experience of bursting into tears when it looks like a poorly wired home-made expansion card has broken the computer (Fortunately, my teenage tantrum was premature: the computer survived my poor soldering). So, as someone who was raised on the do-it-yourself ethos of the BBC Micro, it is gratifying to me to see a new generation of programmers getting into the internals of a computer and finding out how they work rather than just using them.

Want to try out the BBC Micro? There are several emulators available, including BeebEm for Windows and Mac, an Android emulator called BeebDroid and a Java emulator from BBC Micros also show up quite regularly on eBay, both in the USA and more often in the UK.

The Motherboard of the BBC Model B. Note the ROM sockets on the bottom right, which allowed the computer to boot straight into software like word processors / 8BS

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