My collection of Acorn computers and peripherals is available here (under construction).

Acorn Atom

The Acorn Atom (1980) had a 1MHz MOS Technology 6502 CPU, 2 kB RAM. and 8 kB ROM. The Atom could be upgraded in many ways - back then, a lot of electronics hobbyists were getting their first “real” computer. This was my first encounter with an Acorn computer - it must have been in 1981.

This computer could be networked using the Acorn-designed ‘Econet’ LAN for schools and small businesses. Note that Econet was specified in 1980, predating the ‘Ethernet’ standard (1983).

Acorn BBC Micro

After the Acorn Atom was released, they started developing the ‘Acorn Proton’. It was faster, and included a new ‘Tube’ interface for Second Processors. When Acorn won a bid to provide a home computer for the BBC ‘Computer Literacy Project’, it was released as the Acorn BBC Model B, or ‘Beeb’, in 1982.

The BBC Micro ran at 2MHz - twice as fast as the Atom. It came with 32 kilobytes of RAM. As with the Atom, programs could be loaded from cassette at 300 or 1200 bits per second, but you could also install extra ROM chips that contained software such as word processors.

It had lots of hardware expansion options and interfaces - including floppy drives, an RS-423 serial port, printer port and an RGB monitor output. Second Processors included an Intel 80286 that would allow you to run MS-DOS programs on your Beeb!

In 1985, a “BBC Model B+” was released in an attempt to address the memory shortcomings of the original BBC Micro.

Acorn Electron

The Acorn Electron (1983) was a low-cost version of the BBC Micro, with several features removed. Some of these features could be added via expansion modules. For example, the ‘Plus 1’ interface adds ROM cartridges, a printer port and joystick interface. The ‘Plus 3’ interface adds a floppy drive.

Due to production issues, Acorn missed the 1983 holiday season sales and was left with at least 250.000 computers in stock. Around that time, the homecomputer and video games bubble had burst. This was the start of the demise of Acorn Computers.

Acorn BBC Master 128

The Acorn BBC Master (1986) was the ultimate 8-bit Acorn computer. The CPU was changed to a MOS Technology 65C12 - an improved version of the original 6502.

It was the first Acorn computer that had a battery-backed CMOS memory chip for configuration settings. Batteries are a huge problem in retro computing, as they tend to leak and cause corrosion in connectors and the PCB itself - sometimes completely destroying the computer.

Acorn Archimedes

Not satisfied with available 32-bit CPU options, Acorn engineers developed their own CPU in 1985: the Acorn RISC Machine (ARM). After Apple invested, the name was changed to mean “Advanced RISC Machines”.

Refurbishing an Acorn computer

Always start by replacing both RIFA capacitors (C1, C2) in your Acorn BBC (Master) power supply. These tend to dry out and crack, causing them to go ‘pop’ and leave a horrible smell.

There is a third capacitor, C9, an electrolytic capacitor that may also need replacing but I have not encountered that yet.