CARING FOR YOUR COMPUTER

Reviewer Alex Heywood takes a selection of books from ZX and computer library shelves and assesses their value for owners of Sinclair Computers

This book, published by INTERFACE, who are well entwined with the National Users' Group, is aimed squarely at the ZX owner, but also caters for those who have computers other than the ZX81. Author Stephen Adams, well known for his construction articles in computer magazines, and for his reviews of ZX add-ons, lists 85 computers (as well as the ZX81) which can use the projects. Well illustrated with circuit diagrams and photographs (plus a few rogue photos of Atoms, BBC Micros and MZ-80Ks) the book assumes no previous knowledge on the part of the person who will construct the projects. Advice on such apparently mundane matters as the correct way to solder, and how to read resistor colour codes, points out that everybody has to start at the beginning.

The projects are varied, and to my inexperienced eye, seemed to represent a range of projects, from the very simple to the more complex. To give you an idea of the kind of book it is, I shall list the projects: Mains operated 5 volt/12 volt power supply; a monitor; a universal gate; tape recorder control; minitone; numeric keypad for the ZX81; giant seven segment display; score board; wheel of fortune; analogue to digital converter (A/D); light pen; shift lock for keyboards; a cheap thermometer (if you ignore the cost of the computer!) ; graphics - function - edit - rubout key for the ZX81; the movable 'occupant'; "unbeatable" burglar alarm; standby power supply; mains supply filter; a logic probe. The contents also include a number of diagrams of basic components (although I imagine most of us already have a pretty good idea of what a loudspeaker looks like), resistor and capacitor colour codes, and useful addresses.

If you are at all interested in building peripherals for your ZX81, this is obviously the place to start. The text and circuit diagrams are clear; the photographs give you some idea of what the project will look like when completed; and no prior knowledge is assumed. 20 Simple Electronic Projects for the ZX81 and other computers - Stephen Adams, Interface, ISBN 0907563112.

EXPANDING BOOKSHELF

John Gilbert looks back at the year's books to help enhance the ZX machines.

In the last year scores of books have been written about Sinclair machines and it seems as if anyone who knows anything about the ZX-81 or Spectrum can enter the literary field and become an author.

During the early days of the Sinclair boom, most authors were content to collect together a few programs and write a short piece about each one. That made a book which could be on the streets in the shortest possible time.

One of the main publishers of ZX books is Interface. Its early contributions to the ZX-81 market included Getting Acquainted With Your ZX-81, by Tim Hartnell, and The Gateway Guide to The ZX-81 and ZX-80. by Mark Charlton. Both books are full of listings and very little explanatory text and similar in content.

Hartnell seems to have made a one-man attack on the book market in the last year. His first books were full of listings and contained little text but his latest have dealt more with the techniques of programming and are more helpful to a computer user.

The rationale for books of listings was that they would give people who had just received their machines something to type-in and play with before beginning to program. That reason no longer applies. Magazines such as Sinclair Programs print listings which first-time users can type-in, so there is no longer a need to fill the pages of a book with long listings.

The lesson does not seem to have been learned. Several companies have published books of program listings for the Spectrum. They are well-produced and colourful but ideal only for first-time users or people not interested in programming. The best of them include Computer Puzzles for Spectrum and ZX-81, by Ian Stewart and Robin Jones from Shiva, and Over the Spectrum from Melbourne House. Over the Spectrum is a book of listings but the introductory text to each program is more comprehensive than in other books.

Details are also given about how to adapt techniques used in the programs to the user's programs. The Shiva puzzle book is exceptional. The authors pose problems and give listings which simulate the problems in an effort to solve them.

At some time in the last year authors must have felt that the market for books of listings had reached saturation point. People wanted to learn how to program and several books on programming techniques appeared.

One of the first on techniques was The ZX-81 Pocket Book, by Trevor Toms, published by Phipps Associates. Toms described several ways of saving memory, a much-discussed subject among ZX users. In the book are several programs which use the techniques described and also provide light entertainment when difficulties arise.

Another book on techniques which caught the imagination of users is the Sinclair ZX-81 - Programming for Real Applications, by Randle Hurley, published by Macmillan. It details several software projects, including a word processor and data filing program. Hurley also deals with memory-saving techniques and problems which may be encountered by a user when programming. The author has promised a book on machine code but it has not been published.

Peek, Poke, Byte and RAM, by Ian Stewart and Robin Jones, and published by Shiva, gained fame for providing an easy introduction to programming for the beginner. The book takes nothing for granted about the reader and contains many things which the ZX-81 manual did not embrace.

The author of a technical book faces two problems. The wording must be precise but not fall into jargon. The author must also try to find new areas to explore and not draw on material used in other books. That does not seem to worry many authors but soon the technical market could be saturated with books on the same structured programming techniques and memory-saving devices.

People need to know about those things but there are already many books which explain them adequately. It would be better if authors were to explore other areas and there are many as yet unexplored ones in computing.

The machine code market for Sinclair machines is still very young but what has been published is very good. One of the easiest books about machine code is Machine Language Programming Made Simple for your Sinclair, published by Melbourne House. The book takes an almost child-like stance but proved very readable and excellent value for the beginner.

Mastering Machine Code on your ZX-81, by Toni Baker, is also a good introduction to the subject but slightly more difficult for the beginner to understand.

Machine code can be entered into the Spectrum with greater ease than the ZX-81 and is expected to make people more willing to use it. Once they start doing so they will have greater programming power at their fingertips. The Spectrum is an ideal machine on which to learn and if this sector of the book market is overlooked it would be a pity.

A new market for ZX books has been opened in the electronics field. Two examples are the ZX-81 Add-on Book, by Martin Wren-Hilton, published by Shiva, and 20 Simple Electronic Projects for the ZX-81 and other computers, by Stephen Adams. It shows how to build things like tape recorder controllers, numeric keypads and even a cheap thermometer. The book explains the working of several add-ons at present available from retailers and includes projects which the reader can set up, including a burglar alarm and a voice recognition system.

The book market is becoming as lively as the software market and no doubt many books will be produced for the Spectrum and the ZX-81 in the months to come.

A general criticism of all the books mentioned is that they are all too costly. Paperbacks which would sell for no more than £3 are being offered at £9.

There are two probable reasons for the high prices of many books. Perhaps the market is so small that the prices have to be high to cover the costs. The other reason could be that the publishers know that people will buy a recommended book at almost any price. The satisfactory solution seems to lie between the two.

The book market needs strict controls over price and quality if it is to survive in the computer field. If companies do not start to reduce prices and publish better-quality books, computer users will become more cautious and selective. That has already begun to happen with software and the signs are that it is starting to happen with books.