Editing Acorn Atom Technical Manual

The '''Atom Technical Manual''' is Acorn Computers' construction and expansion manual for the [[Acorn Atom]], issue 2, October 1980, copyright Acorn Computers Ltd 1980. The scan has 22 pages, printed pages 1 to 23, and carries a searchable text layer.

The Atom was sold as a kit or assembled, and the manual is written for the person building it. Acorn describes it as containing "the information needed in order to construct the ATOM kit and add any of the extensions", and refers users of assembled machines to the book ''Atomic Theory and Practice''.

== Contents ==

Acorn's contents list, with printed page numbers:

{| class="wikitable"
! Section !! Page
|-
| Introduction || 3
|-
| Construction procedure: parts list (6), layout diagrams (8), TV/video monitor (13), power supply (13), switching on (14), tape recorder (14), output ports (15) || 4
|-
| Circuit description || 16
|-
| Block diagram || 18
|-
| Memory map || 20
|-
| Expanding the ATOM: lower text space (21), video graphics (21), floating point (22), versatile interface adaptor (22), printer interface (23), bus buffers (23), Eurocard extension (23), other extensions (23) || 21
|}

== What it settles ==

* The parts list (pp. 6–7) gives every base-kit IC, resistor and capacitor by designator, and the component and keyboard location diagram (pp. 8–9) shows where each goes. These are the source for the values on [[Acorn Atom Capacitor Replacement Guide]].
* The electrolytics C2–C5, C8 and C11–C13 may be any value from 10 to 47&nbsp;µF rated 10&nbsp;V or more, and Acorn may have supplied substitutes such as 100&nbsp;nF for 47&nbsp;nF. A board that differs from the list is not necessarily modified.
* Acorn capacitors are marked with a three-digit code: two digits of value then the number of zeros, in picofarads (103 is 10&nbsp;nF).
* Power (p. 13): 8&nbsp;V DC in, regulated by IC53 and IC54 (LM340T-5); the high-efficiency adaptor delivers up to 1600&nbsp;mA; the current budget; Atoms before October 1980 used normal-power RAM that the adaptor cannot support fully expanded; links LK6 and LK7 for a regulated 5&nbsp;V input; and a circuit for a 5&nbsp;V 3&nbsp;A supply (9&nbsp;V 50&nbsp;VA transformer, bridge, 1500&nbsp;µF 16&nbsp;V, LM323K).
* Tape (pp. 14–15): SK2 pin use, the 300&nbsp;mV RMS levels, and R29 and R34 as the level and gain resistors.
* The memory map (p. 20), with the IC pair behind each 1&nbsp;KB of RAM, and the opening-the-case procedure (p. 21).

== What this manual does not contain ==

* No fault-finding procedure. The only check given is to recheck connections and construction if there is no display. Acorn offered repairs at Cambridge, at around ten pounds plus parts for machines over six months old.
* No full circuit diagram. The text refers to "the circuit diagram" for the PL5 and PL6 pin-outs, which was a separate sheet; it is hosted here as [[:File:Acorn Atom circuit diagram.png]].
* Nothing on the inside of Acorn's mains adaptor.

== Pages that cite this document ==

* [[Acorn Atom]]: IC list, memory map, power, tape and expansion details.
* [[Acorn Atom General Maintenance]]: case opening, power checks, tape levels and connectors.
* [[Acorn Atom Troubleshooting Guide]]: designators, keyboard scanning and the regulators.
* [[Acorn Atom Capacitor Replacement Guide]]: capacitor values and the substitution rule.

<pdf> File:Acorn Atom Technical Manual.pdf </pdf>

Download: [[:File:Acorn Atom Technical Manual.pdf|Acorn Atom Technical Manual.pdf]]

[[Category:Acorn Service Manuals]]
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