Acorn A680 Technical Reference Manual

The Acorn Technical Publishing System Technical Reference Manual is Acorn Computers' hardware reference for the Acorn A680, which Acorn called the Acorn Technical Publishing System. Part number 0474,905, issue B, July 1988. Chris Whytehead scanned it from the manual that came with his A680 and published it in three parts: the text in two PDFs (114 and 164 pages, with a text layer) and the large drawings as separate files. The circuit references in the manual apply to the issue 1 main PCB.

Contents

Contents (printed pages)

Chapter or appendix	Pages	Hosted file
1 Product overview; 2 Main PCB system overview	1 to 8	Part 1
3 Processor and memory (ARM, master and slave MEMC, clocks, memory array, ROM)	9 to 22	Part 1
4 The hexadecimal display, including the test ROM LED diagnostics	23 to 24	Part 1
5 The input/output system (IOC, printer port, serial port, floppy controller, clock/RAM)	25 to 56	Part 1
6 SCSI; 7 Video; 8 Sound; 9 Keyboard and mouse	57 to 100	Part 1
10 Podules and backplane	101 to 136	Part 2
11 Laser printer interface podule; 12 Cartridge tape podule	137 to 158	Part 2
13 Power supply unit	159 to 162	Part 2
14 to 20 Floppy drive, cartridge tape drive, internal hard disc, monochrome monitor, external storage unit, streaming tape, external hard disc	163 to 188	Part 2
21 Ethernet podule	189 to 204	Part 2
Appendices A and B, circuit diagrams and assembly drawings	205 to 230	Part 2 (reduced); drawings file
Appendix C, system PCB links and test points	231, 232	Part 2
Appendix D, parts lists: main PCB, Ethernet podule, laser printer podule, streamer tape podule, 4-way backplane	233 to 256	Part 2
Appendices E to I: device data sheet list, connectors, mechanical specification and standards, bibliography, silk-screen diagrams	257 to 280	Part 2

What it settles

• The power supply (chapter 13): a 120 W high-frequency switching unit with +5 V (trimmer adjustable, 4.95 to 5.25 V, 2 to 12 A), +12 V (11.3 to 12.7 V, 0.5 to 3 A), −5 V (0 to 0.25 A) and −12 V (0 to 0.5 A); over-voltage protection on +5 V at 5.8 to 7.0 V; 198 to 264 V input, link-selectable for 90 to 135 V; and the pin assignments of its output cable.
• The built-in hexadecimal display (chapter 4) and the meaning of each test ROM code from 0 to F, the means of diagnosing a board that cannot drive the monitor.
• The clock and CMOS RAM supply (chapter 5): a PCF8583 (IC54) backed by a two-cell dry battery, with diodes D7 and D8 and test point TP3 for the battery voltage.
• The memory options (chapter 3): 4 MB with one MEMC or 8 MB with a master and slave MEMC, and the links that go with each (Appendix C).
• The main PCB parts list (Appendix D), including its electrolytic capacitors and fuses, and the mechanical specification (Appendix G).

What it does not contain

• No internal circuit of the power supply, the monitor or the drives; each is described by its specification only.
• In part 2, Appendices A, B and I are reduced scans of some of the drawings, with pages that carry only a heading between them. The full-size drawings are in the separate drawings file.
• The user guide, programmer's reference manual and service manual that it refers to are not online. Chris Whytehead lists all three as wanted.
• The SCSI chapter calls F1 a 1 A fuse, while the main PCB parts list gives F1 as 500 mA.

Drawings

The drawings file (File:Acorn Technical Publishing System (A680) Technical Reference Manual drawings.pdf) has, in order: main PCB circuit diagram sheets 1 to 8; the main PCB silk-screen diagram; the main PCB assembly drawing; and the 4-way backplane, Ethernet/Cheapernet podule, laser printer interface podule and streamer tape controller podule.

Pages that cite this document

• Acorn A680

Downloads: part 1, part 2, drawings