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1980s Computers Explanation of terms

The Archimedes A300 Series

Archimedes A305


Acorn Computers Ltd (UK)


Archimedes A305 and A310

Date Launched

September 1987


£800 for A305
Approx. £900 for A310

Microprocessor type

ARM 2 @ 8 MHz
(Custom designed RISC processor)

ROM size

512 kilobytes

Standard RAM

512 kilobytes in A305
1024 kilobytes in A310

Maximum RAM

1024 kilobytes

Keyboard type

Good quality typewriter style
There was a clear plastic cover just above the function keys. Printed keystrips for a particular program could be put under this as a reminder of the operation of the function keys.

Supplied language


Text resolution

Many different combinations, up to 132 x 32 characters

Graphics resolution

Various, up to 640 x 512 pixels

Colours available

2, 4, 16 or 256 different colours on screen.
The 2, 4 or 16 colours could be chosen from a palette of 4096 whereas the 256 colours were fixed.

Example Screenshot

Archimedes screen
This shows a version of the legendary space-trading game Elite running on the Archimedes.


8 channels, stereo, through internal speaker or external hi-fi.

Cassette load speed

Disc only
800 KB floppy disc built in.

Dimensions (mm)
Weight (grams)

280 x 300 x 75 (main unit)
Not known

Special features

Had space for internal 'podules' which were expansion cards which could also contain their own ROM, allowing 'plug and play' operation.
The Archimedes was the first mainstream desktop computer to use a RISC (Reduced Instruction Set Computer) processor. The ARM 2 was claimed to make the Archimedes around five times faster than the then current IBM PC AT.
The Archimedes brought anti-aliased fonts to desktop computers. Antialiasing smooths the edges of text to make it easier to read. The effect is especially noticeable on italic text, as shown in the image below:

Comparison of italic text under Windows and RISCOS
Times Roman Italic as displayed by Windows Millennium (2000, top) and RISCOS 3.1 (1992, bottom).

Good points

A very fast structured BASIC.
Advanced graphics and sound.
A rudimentary WIMP operating system (written in interpreted BASIC!).
Could run much of the vast amount of software written for the Acorn BBC Model B via a supplied emulator.

Bad points

Expensive, especially when expanded to 1 MB of RAM and a hard disc.

How successful?

As with the BBC B, the Archimedes and later models sold well to schools but was eventually ousted by the 'standard' (but in some ways inferior) Wintel PC from the mid 1990s.
The Archimedes had a small but loyal following among home users.


The A305 and A310 were identical apart from the amount of RAM.
In the mid 1980s most computer manufacturers were moving up from 8-bit microprocessors like the Z80 and 6502, to 16-bit ones such as the 8086 and 68000.
Acorn were not satisfied with any of the available 16-bit models so they decided to design their own - the 32-bit ARM 2 (Acorn RISC Machine.) Steve Furber and Sophie Wilson did most of the design work.
The Archimedes was technically superior to most other available computers, particularly when the full RISC OS WIMP operating system was released.
Unfortunately it was always relatively expensive and never sold in sufficient numbers to challenge IBM PC compatibles. Acorn closed its computer division in the late 1990s but the ARM processor lives on. Its low power consumption means that derivatives of it are used in many mobile phones.

Magazine cover  Read a contemporary review of the Archimedes.

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