Acorn System 1
Upper board, featuring keypad and LED display.
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| Developer | Acorn Computers |
|---|---|
| Type | 8-bit semi-professional |
| Release date | March 1979[1] |
| Introductory price | £65 (kit), £75 (assembled)[2] |
| CPU | 6502 |
| Display | LED |
| Input | 25-key keypad |
| Successor | Acorn System 2, Acorn Atom |
The Acorn System 1, initially called the Acorn Microcomputer (Micro-Computer), was an early 8-bit microcomputer for hobbyists, based on the MOS 6502 CPU, and produced by British company Acorn Computers from 1979.
The system was designed by then-Cambridge-undergraduate student Sophie Wilson.[3] It was Acorn's first product, and was based on an automated cow feeder.[3][disputed ]
It was a small machine built on two Eurocard-standard circuit boards 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 keys), 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.
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, 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.
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.
See also
References
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