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:
Our Archimedes 440: S/N 27-AKB20-1000002
