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Acorn Electron

1983–1985 · desktop

Specifications

Cpu: MOS Technology 6502A, 2 MHz
Ram: max: 32 KB directly addressable; the ULA shared this RAM with the display, which slowed the CPU in higher-resolution graphics modes · base: 32 KB
Ports: Composite video · UHF/RF TV output · Cassette port · Analogue joystick/expansion port (via the ULA, used by Plus 1 and Plus 3 expansions) · Analogue stereo audio (mono in practice)
Display: Cut-down version of the BBC Micro's video modes via a single custom ULA, up to 640x256 in 2 colors or 320x256 in 4 colors; composite and UHF/RF output only, no separate RGB port on the base unit
Storage: base: Cassette tape via the built-in cassette port (no internal storage) · options: Acorn Plus 3 add-on unit adding a 5.25" floppy disc interface
Os Support: latest: BBC BASIC II / MOS in ROM, unchanged across the production run · shipped: BBC BASIC II with a cut-down MOS operating system, both in ROM
Release Price: £199

Upgrade paths

ports

Acorn Plus 1 expansion adding a parallel printer port, RS-423 serial, an analogue joystick port, and two ROM cartridge slots · Plugs into the single expansion connector on the back of the case; widely used to add a printer since the base machine had no Centronics port.

~£60 at the time

EASY

storage

Acorn Plus 3 unit adding a single 5.25" floppy disc drive via the ADFS filing system · Bulkier than the Plus 1 and less common; most Electron software stayed on cassette, so disc drive uptake was limited.

~£130 at the time

MODERATE

other

Third-party second processor and sideways ROM boards, e.g. from Slogger and Pres · The Electron was designed as a cheaper, single-chip cut-down BBC Micro, so it lacked the Tube and 1 MHz bus interfaces of the Model B; expansions had to work through the more limited external connector instead.

varies, typically £30 to £100 in period

HARD