Acorn Archimedes A420/1

The Acorn Archimedes A420/1 was the middle A400/1 workstation, combining 2MB RAM with a 20MB hard disc. It otherwise shared the ARM2 chipset and expandable desktop enclosure of the A410/1 and A440/1.

Its balanced memory and storage specification made the A420/1 a practical professional RISC OS system without the cost of the 4MB flagship.

Notable Features

• Acorn ARM2 at 8 MHz provides the system’s processing architecture.
• The standard memory configuration was 2MB; expandable to 4MB.
• Storage was supplied as 800KB floppy drive and 20MB internal hard disc.

Historical Significance

• Its balanced memory and storage specification made the A420/1 a practical professional RISC OS system without the cost of the 4MB flagship.
• This record separates a genuine processor, memory, enclosure or storage model from software bundles and dealer-only configurations.

Collector’s Notes

• Confirm the exact model from its front badge and rear serial label because many Acorn systems were upgraded during their working lives.
• Original monitors, three-button mice, keyboards, expansion podules, manuals and installation media add historical value.

Specifications

Technical Information
Name	Acorn Archimedes A420/1
Manufacturer	Acorn Computers
Launched	Monday, May 1, 1989
Discontinued	1991
Country	United Kingdom
CPU	Acorn ARM2 at 8 MHz
Units Sold
Operating System	RISC OS 2
I/O	Video, audio, serial, parallel, Econet option and four podule slots
Keyboard	Separate 103-key keyboard and three-button mouse
Storage	800KB floppy drive and 20MB internal hard disc
Sound	Eight-channel, eight-bit stereo sound
Graphics	Acorn VIDC supporting high-resolution colour and monochrome modes
Display	External RGB, VGA-compatible or multiscan monitor
ROM	512KB RISC OS ROM
RAM	2MB; expandable to 4MB
CPU Speed	8 MHz