Update August 2021. A long-forgotten email from Paul Fellows has been found and reproduced here. A good read. I've also moved the potted history that was originally at the bottom of this page to its own page, here.

Clive Sinclair has a lot to answer for :) One of his long-term employees at Sinclair Radionics was one Chris Curry, who started Science of Cambridge for Clive and was a part of the small team who built the MK14 (one of the very first cheap home kit computers at £39.95) and the Sinclair wrist calculator. He wanted to expand the MK14 to have a BASIC interpreter and TV connection but Clive didn't since he was already pursuing the design of the Newbrain, so they parted company and Chris set up Acorn with a Cambridge University friend, Hermann Hauser.

The first machine they came up with was the System-1 in 1978, a 6502 based single board computer (SBC) that ran BASIC. It became the basis for their first 'real' machine, the Atom. Like most machines of the day aimed at the hobbyist market the Atom came as a kit to be soldered at home and later was available as an assembled system.

Next up came the concept of a machine called the Proton. It was to be a 16K machine with enhanced BASIC, colour, sound and expandability, but design issues meant it's development was stalled....also around this time the UK Government were pushing their Computer Literacy for Schools campaign and wanted a low-cost computer that could spearhead it; initially they were just going with the Newbrain from Newbury Labs, but production difficulties, a 2 year wait AND angry letters from Chris Curry and Clive Sinclair forced them to rethink. Initially they hadn't considered Sinclair and Acorn because they wanted a colour Z80 machine - the ZX81 was monochrome and the Atom was 6502 based.

The Proton was now nicknamed the Beebon and a rushed system was done in less than a week, and I have it on good authority that despite Fred Harris using a Beebon in the first series of 'The Computer Programme' the machine actually doing the work was a System 3 that sat under the desk :o)

Uncle Clive also got the Spectrum out the door faster than he should've done to go against the BBC, but the keyboard and lack of networking meant the Beebon still won and became the BBC Micro.

Acorn nearly lost out again a couple of years later; they'd sat on their laurels for too long when they should've been producing a followup machine to the BBC, so while the next generation of Beebs was in development they had to produce souped-up versions of the BBC Model B, resulting in a B+ 64K and a B+ 128K before the BBC Master hit the streets in 1986.

The 'standard' Master featured 128K RAM, better sound capabilities, enhanced BASIC, and several apps built in to the MOS ROM such as View, ViewSheet, Terminal and the ADFS ROM for disk access ("A" for 'advanced' - though disks written using ADFS weren't compatible with the DFS chip in the Model B). Unfortunately there were also some compatability issues with earlier BBC B software, but that didn't stop anyone; in the first 3 years of production over 200,000 Masters went out the factory.

Upgrades were produced too, a 512K RAM variant and the Turbo, which featured a 65C02 co-processor - it was this machine that was used for the Domesday System.

After this Acorn started developing their own CPUs, called ARM (Acorn RISC Machine), and the first machines to get the new CPUs were the Archimedes range, which started with the A305 and ended with the A7000+ in the mid-90s after Acorn had quit home computing to concentrate on CPUs and embedded systems. Cash problems had meant a brief marriage to Olivetti before finally giving up the ghost. Castle Technology bought the rights to the Archimedes and RISC PC range and still support them today.

*Update* - Courtesy of Gavin Saxby (originally) and Rich Kilpatrick I now have in my paws a fully working Acorn Cambridge Workstation with a handful of disks and missing keyswitch. Yes folks, if you're googling for ACW related stuff you'll find entries on the likes of old-computers.com....the machine I have is that machine :oD

*update 2* - a machine I didn't know existed until recently even though its story ended in 1998 with the closure of Acorn's Workstation division. The Phoebe 2100 or RiscPC2 never saw the light of day owing to overambition and flaws in its IOMD2 chip which I see as a ULA/ASIC thus nicely bringing back the ULA problems that dogged Acorn (and others) in the 80s. There's lots of writeups on Phoebe (yes, named after the 'Friends' character Phoebe Bouffet) already so I won't bother linking to them here. What I will show is the pictures of the machine at the Wakefield RiscOS show yesterday (13/05/06) on the Binary Dinosaurs stand courtesy of Andrew Whickham and Retrobeep at Bletchley Park. Link is in the menubar. Oh, the machine we showed is this one.

System 1, unbuilt kit, CPU board only so I don't have the keyboard or display card.
Atom, original kit-built unit with schematic and extra chips. Came with tapes and the world's largest domestic PSU :)
Electron, fully boxed mint with all the manuals and a load of games.
Retail boxed Electron, mint but missing the cassette leads. Nice cover!
Electron on its own with attached Plus-1 extender.
Mint BBC-B with Cub monitor and Cumana disk drive.
BBC-B with issue 3 board and a serial number of less than 20,000. "Patent Pending" don'tcha know!
Mostly boxed Beeb B with manual. Almost mint condition too, from Bainbridges no less :)
64K BBC B+ (didn't know these existed!)
BBC Master 'Domesday' setup complete with LV-ROM drive, trackball and Mouse.
Second Domesday setup - Master AIV, Philips VP415 Laservision player, trackball and discs. Philips' demo unit #7!
BBC Master 'Domesday' machine. BBC Enterprises unit #3, Issue 1 machine (12/85) with Cox 630B Genlock, used to create Domesday disc video content!
BBC Master boxed with option ROMS, disks and floppy drive
BBC Master Turbo with excellent condition dual Cumana floppy.
BBC Master boxed with floppy drive.
BBC Master Compact x2 - 2 piece machine with *gasp* 3 1/2 inch floppies.
BBC B+ *box* from Lee, in new condition :)
Acorn Cambridge Workstation aka the ACW-210, working. Cheers Rich & Gavin!
Archimedes A3000 with monitor, rodent and some disks.
Archimedes A3010 with monitor and manuals, still with product 'wow look what this can do' flash stuck to it! 32bit! Woo.
Archimedes A3020 with monitor, mouse and MIDI expansion unit.
Archimedes A4000 with monitor, keyboard and HP500 Deskjet printer.
Archimedes A5000 with keyboard.
A7000 with keyboard and monitor. Nice machine!
A7000+ from Russ Smith, working after a hardware reset. Thanks Russ!
Archimedes A310, boxed with boxed monitor and keyboard.
Archimedes A410/1 with monitor, keyboard, rodent etc
Prototype Archie A540 from Rich Kilpatrick. I know it's a prototype because it has 'prototype' stamped on it :) Unfortunately it's been 'parcelforced' so it's a bit bent.
RiscPC 640 on its own, don't know if it works yet.

6502 second processor for the B
32016 Co-processor for the BBC Master.
Torch Disk Pack including Z80 Communicator co-processor
Teletext adapter for the B with ROMs and keyboard overlay.
'Advanced' teletext adapter for the B
Keyboard for the Archimedes 5000
BBC 5 1/4 Floppy Disk Drive
Opus floppy drive
Electron Data Recorder, mint with PSU and manual
Acorn Program recorder
BBC Program recorder
Cumana double 5 1/4 floppy for the beebs
Plus-1 ROM extender for the Electron, boxed perfect but missing manual
Plus-3 3 1/2" floppy add-on for the Electron
Some sort of Music Synthesizer for the Beeb
Ethernet modules for the Archimedes 3000 and 5000, boxed unused.
Econet modules for the Beeb B.
Severalteen Electron games, boxed, some mint.
View ROM cart for the Electron Plus-1, not bad condition.
Wizard Joystick interface and sideways ROM board for the Electron in excellent nick.
Microvitec Touch Screen addon for the Cub monitors, courtesy of Rich Harding's local tip :)

*rare* - 3 Master Compacts! *grin*
Electron with Plus-1 and Plus-3 addons, er, added on.