Acorn System 5 Handbook
The Acorn System 5 Handbook is Acorn Computers' handbook for the Acorn System 5, reference 400,056/1, dated 1 March 1983. It was written and produced for Acorn by Arch Technical Publications Limited of Hitchin. The cover carries a 1983 copyright; the contents page and each board section carry ©1982. The hosted PDF has 122 pages and an OCR text layer, so it is searchable, though the OCR has mangled some characters.
Each board section has its own Acorn document number and page sequence, so citations to this handbook give the section and its printed page.
Contents
[edit | edit source]| Part and section | Document | What it covers | PDF pages |
|---|---|---|---|
| Front matter | 400,056/1 | Title page, mains wiring and earthing warning, how to use the handbook, contents | 1–5 |
| Part 1, Section 1: Disc Operating System | – | Disc handling; what is supplied in the System 5 (p. 1); getting started; DOS features; commands and error messages (pp. 14–17); utilities INFALL, COPY, COMPACT, COPYF, DUTY, FORM40/FORM80 (pp. 18–19); sequential files; assembly-code access to DOS (pp. 21–24) | 6–33 |
| Part 2, Section 1: Rack, PSU and Backplane | – | Rack and cabinet, leading particulars, AC9231 power supply, Table 1 supply connections, Table 2 typical loads, backplanes and Table 3 Acorn Bus pinout, parts list (pp. 1–4) | 34–38 |
| Part 2, Section 2: 6502A CPU Board | 400,005 | Leading particulars, circuit description, clock links (p. 7), VIA, software parameters, parts list (p. 21), circuit diagram (p. 23) | 39–62 |
| Part 2, Section 3: 32K DRAM Board | 400,010 | Address decoding, clock links, local oscillator setting-up procedure (p. 6), refresh, paging, parts list (p. 8), circuit diagram (p. 9) | 63–73 |
| Part 2, Section 4: 80 × 25 VDU Board | 400,019 | HD46505 CRTC, character generation, clocks, parts list (p. 15), circuit diagram (p. 17) | 74–93 |
| Part 2, Section 5: Floppy Disc Controller Board | 400,004 | Intel 8271 controller, drive connections (p. 11), parts list (p. 12), circuit diagram (p. 13) | 94–108 |
| Part 2, Section 6: Acorn Keyboard | 400,013 | AY-3-4592 encoder, reformat circuit, connections, parts list and power-on reset option (p. 6), circuit diagram (p. 7) | 109–116 |
| Part 2, Section 7: Econet Board | – | ADLC, line driver and receiver, collision detect, station number links, parts list (pp. 3–4), circuit diagram (p. 5) | 117–122 |
What it settles
[edit | edit source]The parts lists give every capacitor with its designator and value, and every board section ends with its circuit diagram. On the 6502A CPU board, for example, C1 is a 22 µF 16 V electrolytic, C2 a 10 µF 16 V tantalum, C3 a 100 pF ceramic disc and C4–C9 are 47 nF ceramics (400,005 p. 21). These lists are the component-level source for the Acorn System 5 Capacitor Replacement Guide.
Part 2 Section 1 specifies the supply, a type AC9231 switch-mode unit mounted behind the card frame:
| Item | Specification |
|---|---|
| Outputs | +5 V at 6 A, −5 V at 0.5 A, +12 V at 2.5 A, −12 V at 0.5 A |
| Input range | 90–135 V AC (115 V nominal) or 180–270 V AC (230 V nominal) |
| Input frequency | 47–400 Hz (50/60 Hz nominal) |
| Hold-up time | 24 ms typical on loss of supply |
| Line regulation | 0.1 % typical |
| Load regulation | 0.2 % typical |
| Fault tolerance | Open or short-circuit loads tolerated indefinitely |
The system draws 0.6 A at 230 V or 1 A at 115 V. The rack measures 480 × 177 × 240 mm and the cabinet 490 × 214 × 350 mm, and the machine weighs about 16 kg with one drive. The card frame takes up to ten 100 × 160 mm Eurocards. Table 2 gives the typical +5 V current of each board and the +5 V and +12 V currents of the Olivetti, Shugart and Tandon drives.
What this manual does not contain
[edit | edit source]- No component data for the power supply. The parts list carries it as one line, "Power supply unit, 1 off, Aztec AC9231"; AC9231 is an Astec part number.
- Printed pages 13 and 14 of the 6502A CPU Board section are missing from the scan (PDF page 53 is p. 12 and PDF page 54 is p. 15). They hold most of the VIA register description and the power-on reset circuit (paras 2.10.2 to 2.11).
- No description of the Teletext VDU board, the 16K DRAM card or the other optional Eurocards. For the wider card range see Acorn System Catalogue.
- No fault-finding chapter or diagnostic flowcharts. The only adjustment procedure is the 32K DRAM board's local oscillator setting-up (400,010 p. 6).
- No coverage of the Acorn System 1, Acorn System 2, Acorn System 3 or Acorn System 4.
Pages that cite this document
[edit | edit source]- Acorn System 5: configuration, boards, clocks and power supply
- Acorn System 5 Maintenance Guide: supply checks, loads and the DRAM oscillator procedure
- Acorn System 5 Troubleshooting Guide: rails, board currents and clock links
- Acorn System 5 Capacitor Replacement Guide: every capacitor value
Download: Acorn System 5 Handbook.pdf