Acorn System 1
 | |
| Acorn System 1 (Acorn Microcomputer), 1979 | |
| Specifications | |
|---|---|
| Developer | Sophie Wilson |
| Manufacturer | Acorn Computers Ltd |
| Type | Single-board microcomputer (kit or assembled) |
| Released | April 1979 |
| CPU | Rockwell R6502 @ 1 MHz |
| Memory | 1 KB RAM (2× 2114), 512 bytes ROM (2× 74S571) |
| Storage | CUTS cassette interface (300 baud) |
| Display | 8-digit 7-segment LED |
| Sound | — |
| OS / Firmware | Monitor in ROM |
| Predecessor | — |
| Successor | Acorn System 2, Acorn Atom |
| Model no. | 200,000 (CPU card), 200,001 (keyboard card) |
The Acorn System 1, first sold as the Acorn Microcomputer, was Acorn Computers' first product. It was designed by Sophie Wilson and shipped in April 1979.[1] It was a small machine built on two 100×160 mm Eurocards, sold as a kit or ready-built, and aimed at hobbyists. The modular, Eurocard-based design led directly to the rack-mounted Acorn System 2 to System 5, and the experience fed into the Acorn Atom and the BBC Micro.[2]
The two cards
[edit | edit source]The System 1 is two Eurocards linked by a ribbon cable:[1][3]
| Card | Part | Key devices |
|---|---|---|
| CPU card | 200,000 | Rockwell R6502 @ 1 MHz; 2× INS8154 RAM/IO; 2× 2114 (1 KB RAM); 2× 74S571 (512 bytes ROM); LM340-T5 5 V regulator; 1 MHz crystal |
| Keyboard / cassette card | 200,001 | 8-digit 7-segment LED display; 25-key hex keypad; CUTS 300-baud cassette interface (LM358 amp, 7445 decoder) |
One INS8154 drives the keypad ribbon; the second drives the EuroConnector, so the CPU card can be used unchanged in a System 2, 3 or 4. The CPU card also has an empty socket for a 2516 EPROM and a second 8154.[1]
Operation
[edit | edit source]The monitor program in the 512-byte ROM lets the user examine and modify memory and registers through the hex keypad and the 8-digit LED display, and save or load via the CUTS cassette interface at 300 baud. There is no video output on the base machine; a VDU requires a System 2-style frame with a VDU Eurocard.
Maintenance and repair
[edit | edit source]- Acorn System 1 Maintenance Guide
- Acorn System 1 Troubleshooting Guide
- Acorn System 1 Capacitor Replacement Guide
Documentation
[edit | edit source]See also
[edit | edit source]- Acorn System 2 · Acorn System 3 · Acorn System 4 · Acorn System 5
- Acorn Atom — the all-in-one home computer derived from this work
References
[edit | edit source]- ↑ 1.0 1.1 1.2 Whytehead, Chris. "Acorn Microcomputer (a.k.a. System 1)", Chris's Acorns / The Centre for Computing History. Source for the 1978 design by Sophie Wilson, the April 1979 release, the two-Eurocard construction, the CPU-card complement (R6502P, 8154 RAM/IO, 2114 RAM, 74S571 ROM, LM340-T5 regulator), the keyboard-card complement (LED display, hex keypad, CUTS cassette interface) and the board part numbers (200,000 / 200,001).
- ↑ "Acorn System", Wikipedia. Source for the series overview, the Eurocard modular concept, the per-machine configurations and prices, and the role of the System 3 in Atom and BBC Micro development.
- ↑ Acorn System 1 Technical Manual (Acorn Microcomputer), Acorn Computers — hosted on this wiki. Source for the CPU-card and keyboard-card IC and capacitor parts lists, the construction notes and the circuit description.