\documentclass[a4paper,12pt]{report}
\pagestyle{plain}
\begin{document}
\title{Repairing HP9800 series calculators}
\author{Dr A. R. Duell\thanks{ard@p850ug1.demon.co.uk}}
\date{March 2011}
\maketitle
\pagenumbering{roman}
\tableofcontents

\chapter{Introduction}
\pagenumbering{arabic}
\section{No Boardswapping!}
There is only one way to repair a calculator (or any other electronic or 
mechanical device for that matter). That is to understand how it works 
and what it should be doing, to make measurements to see what actually 
{\em is} doing, then to work out what faults are causing the observed 
behaviour to differ from the correct behaviour and then (and only then) 
to correct those faults. Essentially random replacement of large parts of 
the machine (for example complete PCBs) will get you nowhere fast!

With that in mind, This manual will begin by describing how the HP9810,
HP9820 and HP9830 calculators work. It won't meniton every logic gate, but
hopefully enough detail will be give so that it's possible to follow the
schrmatics nad understand exactly waht every seciton does. Further
chapters will describe how to dismantle and inspect the machine, trace
faults in the logic and perform the mechanical repairs that are almost
always necessary. 

For the purposes of the description, I will divide the machine into the
following sections : The bit-serial, microcoded {\bf Central Processor}; 
The {\bf Memory System}, containing the ROM and RAM boards, the memory
address and data registers and the associated control circuitry;  The {\bf
Display} and its driver circuitry;  The {\bf Keyboard} and its encoder
circuitry;  The {\bf Printer}, or in the case of the 9830 the printer
interface;  The {\bf Storage Device} -- either the magnetic card reader of
the 9810 and 9820 or the cassette tape drive of the 9830;  and finally the
{\bf Power Supply}

\section{Sources of further information}

In order to follow the descriptions, it is necessary to have the schematic
diagrams for the machine, and data sheets on the ICs used. Therefore a 
TTL Data Book is very useful, but it needs to be a fairly old one to 
include some of the devices used.

Many of the ICs ins the actual machine will be marked with an HP `house
number' rather than the industry-standard code. A list of equivalents,
such as the ones published in HP `Bench Briefs' is almost essential when
you come to do actual logic repairs. It is important to note that devices
are removed from later lists (if no instrument supported by HP at that
time uses the device, it will be removed), so you may have to check
several such lists. 

The HP service manuals are what I somewhat pejoratively call `boardswapper
guides' but they do contain a little useful information and are worth
reading too. Finally, to fully understand the operation of the processor,
is is useful to have a source listing of the microcode. 

\chapter{CPU Theory of Operation\\}

\input{cpu_1.tex}

\input{cpu_2.tex}

\chapter{Memory System Theory of Operation\\}

\input{mem_intro.tex}

\input{mem10.tex}

\input{mem20.tex}

\input{mem30.tex}

\chapter{Display Theory of Operation\\}

\input{display.tex}

\chapter{Keyboard Theory of Operation\\}

\input{keyboard.tex}

\chapter{Printer theory of Operation\\}

\input{printer.tex}

\chapter{Storage System Theory of Operation\\}

\input{storage.tex}

\chapter{Power Supply Theory of Operation\\}

\input{psu.tex}
\chapter{Tools and Test Equipment\\}

\input{tools.tex}

\chapter{Dismantling the Machine\\}

\input{dismantle.tex}
\chapter{Electronic Troubleshooting\\}

\input{elect.tex}~
\chapter{Repairing the HP9810/HP9820 Card Reader\\}

\input{card.tex}

\chapter{Repairing the HP9810/HP9820 Printer\\}

\input{prtmech.tex}

\chapter{Repairing the HP9830 Cassette Drive\\}

\input{tapemech.tex}

\chapter{Final Comments}

\input{final.tex}

\end{document}

