The Acorn System 1, initially called the Acorn Microcomputer (Micro-Computer), was an early 8-bit microcomputer for hobbyists, based on the

MOS 6502 The MOS Technology 6502 (typically pronounced "sixty-five-oh-two" or "six-five-oh-two") William Mensch and the moderator both pronounce the 6502 microprocessor as ''"sixty-five-oh-two"''. is an 8-bit microprocessor that was designed by a small ...

CPU, and produced by

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories and Crown Dependencies. * British national identity, the characteristics of British people and culture ...

company

Acorn Computers Acorn Computers Ltd. was a British computer company established in Cambridge, England in 1978 by Hermann Hauser, Christopher Curry (businessman), Chris Curry and Andy Hopper. The company produced a number of computers during the 1980s with asso ...

from 1979. The main parts of the system were designed by then-

Cambridge Cambridge ( ) is a List of cities in the United Kingdom, city and non-metropolitan district in the county of Cambridgeshire, England. It is the county town of Cambridgeshire and is located on the River Cam, north of London. As of the 2021 Unit ...

-undergraduate student Sophie Wilson, with a cassette interface designed by Steve Furber.http://www.stairwaytohell.com/articles/SG-SophieWilson.html Sophie Wilson - 2007 Interview with Stuart Goodwin It was Acorn's first product, and was based on an automated cow feeder. It was a small machine built on two Eurocard-standard

circuit board A printed circuit board (PCB), also called printed wiring board (PWB), is a laminated sandwich structure of conductive and insulating layers, each with a pattern of traces, planes and other features (similar to wires on a flat surface) ...

s and it could be purchased ready-built or in kit form. *one card (shown right) with the I/O part of the computer: a LED seven segment display, a 25-key keypad ( hex+

function key A function key is a key on a computer or computer terminal, terminal computer keyboard, keyboard that can be programmed to cause the operating system or an application program to perform certain actions, a form of soft key. On some keyboards/com ...

s), and a cassette CUTS interface (the circuitry to the left of the keypad) *the second card (the computer board - see below), which included the CPU, RAM/ ROM memory, and support chips *the two boards were interconnected by a semi-flexible, multi-conductor cable, known by its commercial name 'Spectra Strip' *the whole assembly was held together by four 2.5mm × 20mm nylon screws and clear plastic spacing tubes for rigidity. Acorn-System-1-Rear-Board

Main Components (left to right) * Top Row: INS8154 RAMIO Integrated Circuit (for keyboard and display), 6502 CPU, 2 × 2114 1024×4 RAM, 2 × 74S571 512×4 PROM, RAM/ROM expansion socket, second INS8154 for peripheral expansion (optional extra with the kit version). * Bottom row: 1 MHz clock

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

, 4 × TTL logic chips providing address decoding for the memory and I/O expansion, 5V regulator. * The smaller empty socket in the middle of the board was used to set the memory map of the RAM, ROM and I/O expansion by fitting or soldering wires between various positions according to the instructions in the Acorn System 1 Technical Manual. * The three semi-circular legends on the bottom left of the board marked positions for optional push switches to trigger the board's RESET, IRQ (Interrupt ReQuest) and NMI (Non Maskable Interrupt) lines. Almost all CPU signals were accessible via the standard Eurocard connector on the right-hand side of the board. This connector was not fitted/supplied as standard with the kit version. The System 1 front board was used as the control panel for the fictional computer Slave in the 1981 series of the

BBC The British Broadcasting Corporation (BBC) is a British public service broadcaster headquartered at Broadcasting House in London, England. Originally established in 1922 as the British Broadcasting Company, it evolved into its current sta ...

science-fiction series Blake's 7.

References

External links

Comprehensive information on the System 1, including an emulator
– Provided by Mike Cowlishaw
Acorn System 1 manuals and schematics at ARCHIVE.ORG
{{Acorn computers Early microcomputers System 1 6502-based home computers

See also

References

External links