In 1991, the A5000 was launched. It featured the new 25 MHz ARM3 processor, 2 or 4MB of RAM, either a 40 MB or an 80 MB hard drive and a more conventional 2U rack pizza box-style two-part case (HxWxD: 100 x 430 x 340 mm). Its enhanced video capabilities allowed the A5000 to 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. This natively supported various formats including DOS and Atari discs. A later version of the A5000 featured a 33 MHz ARM3, 4 or 8 MB of RAM, an 80 or 120 MB hard drive.

The A5000 initially ran the new 3.0 version of RISC OS, although several bugs were identified; most were shipped with RISC OS 3.10 or 3.11. As before, earlier machines were capable of being upgraded to the new RISC OS 3, though some needed help, as well as the ARM3 CPU. Earlier models could also benefit from the video performance of the A5000 via a third party upgrade.

Source: Wikipedia, "Acorn Archimedes", available under the CC-BY-SA License.