ACORN ARCHIMEDES

The 'Acorn Archimedes' was Acorn Computers Ltd's first general purpose home computer based on their own 32-bit ARM RISC CPU. The name is also commonly used to describe computers which were based on the same architecture, even where Acorn did not include 'Archimedes' in the official name.

Contents

Description and History

Early models

The A3000 and A5000

A new range and a laptop

List of models

Significance and impact

See also

External links

Description and History

Early models

The first models were released in June 1987, as the 300 and 400 series. The 400 series included 4 expansion slots (although a 4 slot backplane could be added to the 300 series) and an ST506 controller for an internal hard drive. Both models included the Arthur OS (later called RISC OS), BBC BASIC and an emulator for Acorn's earlier BBC Micro, and were mounted in two-part cases with a small central unit, monitor on top, and a separate keyboard and three-button mouse. All models featured onboard 8 channel stereo sound and were capable of displaying 256 colours on screen.
Four models were initially released with different amounts of memory, the A305, A310, A410 and A440. The 300 and 400 were followed by a number of machines with minor changes and upgrades:

The A3000 and A5000

Work began on a successor to the Arthur operating system, initially named Arthur 2, but with the release of the it was renamed to RISC OS 2. Along with it, a number of new machines were introduced as well, and in May 1989 the 300 series was phased out in favour of the new Acorn A3000. The earlier models were capable of being upgraded to RISC OS 2 by replacing the ROM chips which contained the Operating System.
Unlike the previous Archimedes models, the A3000 came in a single-part case similar to the Amiga 500 and Atari ST computers, with the keyboard attached to the main unit. This kind of housing consumes a lot of desktop space, a problem that Acorn tried to overcome by offering a monitor stand that could be attached to the base unit. The new model only sported a single expansion slot. Unlike the 300 series, the 400 series was kept in production.
The other new model, the A5000, came in a newly designed two-part case that looked more conventional than the housings of its predecessors. It featured the new 25 MHz ARM3 processor, while the A3000 was still equipped with an 8 MHz ARM2. The A3000 ran RISC OS 2, while the A5000 ran the new RISC OS 3.0. It came with 2 or 4 MB of RAM, compared to the A3000's 1 MB, and featured either a 40 MB or an 80 MB hard drive. Its video capabilities were enhanced as well and the A5000 could comfortably display VGA resolutions of up to 800×600 pixels. It was the first Archimedes to feature a High Density capable floppy disc drive as standard and could read and write various formats, including DOS and Atari discs. A later version of the A5000 was available, featuring a 33 MHz ARM3, 4 or 8 MB of RAM, an 80 or 120 MB hard drive and a revised OS, namely RISC OS 3.10.
As previously, earlier machines were capable of being upgraded to the new RISC OS 3, though some needed help[1], as well as the ARM3 CPU.[2] Via a third party upgrade,[3] earlier models could benefit from equal video performance to the A5000.

A new range and a laptop

In 1992, a new range was produced, using the ARM250 microcontroller, an ARM2 processor with integrated memory and video controllers, performing better thanks to an increase in clock frequency, and running RISC OS 3.10. The A30x0 series had a one-piece design, similar to the A3000 but far smaller, while the A4000 looked like a slightly slimmer A5000. The A3010 model was intended to be a home computing machine, featuring a TV modulator and joystick ports, while the A3020 targeted the home office and educational markets, featuring a built-in 2.5" hard drive and a dedicated network interface socket . Technically, the A4000 was almost identical to the A3020, only differing in hard disk size (3.5" in the A4000), though it sported a different appearance. All three ARM250-based machines could be upgraded to 4MB with plug-in chips (though the A3010 was designed for 2MB, third party upgrades overcame this) and one "mini-podule" slot as used for internal expansion in the A3000.
Also in 1992, Acorn introduced a laptop computer called A4 that featured an ARM3 processor like the A5000, even though it had a slightly lower clock speed, and a LCD screen capable of displaying a maximum resolution of 640 × 480 pixels in 16 levels of grey. However, it did feature a monitor port which offered the same display capabilities as an A5000. A notable omission from the machine was a built-in pointing device, requiring users to nagivate with the cursor keys or attach a conventional Acorn three-button mouse.[4]
The ''A7000'', despite its name being reminiscent of the Archimedes naming conventions, was actually more similar to the Risc PC – the line of RISC OS computers that succeeded the Archimedes in 1994. It lacked, however, the DEBI expansion slots and multi-slice case that characterized the RiscPC (though by removing the CDROM, a backplane with one slot could be fitted).

List of models

Model	Memory (RAM)	Hard disk space	Launch date	UK retail price at launch	Notes
BBC Archimedes 305	512 KB	-	July 1987	£899	-
BBC Archimedes 310	1 MB	-	July 1987	£999	-
Acorn Archimedes 410	1 MB	-	July 1987	£1299	Appears only in marketing literature; may never have been produced
Acorn Archimedes 440	4 MB	20 MB	July 1987	£1499	-
BBC A3000	1 MB	-	May 1989	£799	This model was the last ever BBC Microcomputer
Acorn Archimedes 410/1	1 MB	- (ST506 interface on motherboard)	June 1989	£999	Improved ''MEMC1A'' memory controller over previous 410 model
Acorn Archimedes 420/1	2 MB	20 MB ST506	June 1989	£1099	-
Acorn Archimedes 440/1	4 MB	40 MB ST506	June 1989	£1299	Improved ''MEMC1A'' memory controller over previous 440 model
Acorn R140	4 MB	47 MB ST506	June 1989	£3,500	RISC iX workstation
Acorn Archimedes 540/1	4 MB	100 MB SCSI	June 1990	£	ARM3 processor
Acorn R225	4 MB	-	July 1990	£	ARM3 processor, RISC iX network workstation
Acorn R260	8 MB	100 MB SCSI	July 1990	£	ARM3 processor, RISC iX workstation
Acorn A5000	1 MB or 4 MB	0 MB to 160 MB IDE	September 1991	£999 or £1499	ARM3 processor, launched with various sub-models
Acorn A4	2 MB or 4 MB	0 MB or 60 MB IDE (2.5")	June 1992	£1399 or £1699	Notebook model with ARM3 processor clocked at 24MHz (1 MHz slower than usual), 640x480 greyscale LCD screen
Acorn A3010	1 MB	-	September 1992	£499	ARM250 processor
Acorn A3020	2 MB	0 MB - 80 MB IDE (2.5")	September 1992	£799	ARM250 processor
Acorn A4000	2 MB	0 MB - 210 MB IDE	September 1992	£999	ARM250 processor

Also produced, but never sold commercially were:

★ A500 - 4 RAM, ST506 interface, Archimedes development machine [5]

★ A680 and M4 - 8 MB RAM, SCSI on motherboard, RISC iX development machines

Significance and impact

The Archimedes was one of the most powerful home computers available during the late 1980s and early 1990s; its main CPU was faster than the 68000 microprocessors found in the more popular Atari ST and Commodore Amiga machines. "An 8 MHz 68000 had an average performance of roughly 1 MIPS." The 8MHz ARM2 yields 4.5-4.8 MIPS in repeatable benchmark tests [6]
The Archimedes won significant market share in the education markets of the UK, Ireland and Australasia; the success of the Archimedes in British schools was due partly to its predecessor the BBC Micro and later to the Computers for Schools scheme organised by the Tesco supermarket chain in association with Acorn, and most students and pupils in these countries in the early 90s were exposed to an Archimedes or A-series computer. Outside of education, despite a technical edge the Archimedes only ever met a moderate success, becoming a 'minority' platform outside of niche markets (not unlike the Apple Macintosh). Niche markets included professional work such as radio, medical and railway station management and music publishing.
By the early 1990s, the UK educational market began to turn away from the Archimedes. Many schools started using Macintosh computers. The increasing multimedia capabilities of IBM compatible PCs also lead to an erosion of the Archimedes market share.

See also

★ BBC Micro - predecessor

★ Risc PC - the next-generation Archimedes

★ Acorn Computers Ltd

★ Arculator

External links

★ Acorn Archimedes site

★ arcem machine emulator released under the GNU GPL

★ RedSquirrel ARM machine emulator

★ Virtual Acorn - commercial Archimedes / RISC OS emulation package

★ Acorn Archimedes memories

★ Acorn Archimedes Emulator related site

★ Castle Technology - Acorn's hardware successor, producing the next generation RISC OS machines

★ RISC OS Ltd - continuing the development of the RISC OS operating system

★ Chris' Acorns - computer 'museum'