The Ins and Outs of the TS 1000 & ZX 81, by Don Thomasson (Melbourne House, $12.95)
THIS BOOK will be a long awaited pleasure for anyone who wishes to soup up his T/S1000,ZX81 with internal modifications or add-on homebrew peripherals. For those of us utterly unfamiliar with electronic hardware, The Ins and Outs might be a bit rough-going at first, but the author makes every effort to present the material in terms that lead to an understanding of the concepts and projects presented. Tinkering with the innards of a computer is something that most of us are understandably nervous about, but Thomasson treats the subject in such a matter-of-fact way that after a few pages even the most reluctant of us will be itching to take the cover off and get inside with a soldering iron.
The first section is devoted to a careful study of the internal layout of the machine. Thomasson discusses the various signals zipping around inside the little black box, how they affect each other, and finally suggests some practical changes to the interior decor. Any of us who have suffered from the dreaded Rampack Wobble will find irresistible a project designed to install RAM (random access memory) chips inside the T/S,ZX. The middle section of the book provides a concise description of the signals available along the edge connector at the back of the machine; this leads quite naturally to the third and final portion, which deals with the addition of external circuitry to the computer. In a book as small as this one it is impossible for the author to cover every possible type of interfacing and to his credit Don Thomasson has not attempted to do so. His approach instead is to start with extremely general advice, and through selected examples of varying difficulty, lead the reader to his or her own solutions to specific application problems.
An aspect which for me justifies the purchase of The Ins and Outs of the TS/1000 & ZX/81 is the very useful (if sometimes roughly drawn) diagrams which are to be found throughout. I was also excited by the final project in the book, which describes a complete control system for a model railway. This is the sort of thing that starts one thinking about the computerized home of the future; with the circuits and techniques presented here, it could be yours sooner than you think.