Those of you who have been following my interesting articles - Hardware Projects - will have picked up some of the basics of using the Electron to control other electronic devices, and I hope that the articles have encouraged you to try a few simple experiments.

One problem has always been how to start, and this book, Control Applications of Microcomputers, although not aimed specifically at Electron users, will get you going in the right direction, though a little extra help may be needed.

In it, Peter Mitchell offers a 160 page introduction to this vast area. The material is clearly aimed at the beginner, and the techniques needed to interface a variety of different devices, such as LEDs and stepper motors, are described.

The material is presented in a fairly easy-going and logical manner with chapters on number systems, logical operators and logic gates and 6502 assembler among the hardware information.

The diagrams are clear and meaningful, and the software side of control is covered with some introductory information on the 6522 VIA as used in the BBC Micro, the ACP Plus 5 and other user ports for the Electron. Listings in Basic and 6502 assembly language are given throughout the book for the Pet - a very old micro, late but not much lamented - Commodore 64 and BBC Micro.

The techniques described will suit any Electron with a user port, and it's just a case of altering addresses referred to in the programs. Anyone with even a limited knowledge of Basic will have little difficulty.

An index is provided, but there's no glossary which would have been particularly useful, as computer control technique is littered with technical terms. Exercise programs are provided with typical solutions.

Control applications rely on at least a small amount of electronic construction. A little practical knowledge would be required to build the circuits described in the book. An absolute beginner might have difficulty due to lack of information on the "nuts and bolts" side of building interfaces such as soldering, where to get components and the resistor colour code.

Anyone expecting a cookbook approach, with fully detailed instructions of how to build the more esoteric devices used in interfacing such as fast analogue-to-digital converters, digital to analogue converters and so on, will be disappointed.

These are covered at a system level - the connections needed to a typical ADC or DAC are there, but no specific circuit details are given. Fair enough, as detailed instructions to build such devices could easily take up a couple of complete chapters - quite a lot of space in an introductory guide such as this.

The book is aimed at users of three computers, and so loses a little of the machine specific information that many of us will be used to. For example, the typical analogue to digital converter referred to plugs into the user port of any of the computers mentioned in the book, but no mention is made of the ADC built into the BBC Micro, information that would be quite useful to Plus 1 owners.

A similar criticism must be levelled at a couple of assembly language listings that write text to the screen. The method shown to write to a BBC Mode 7 screen is to access it directly wth an STA instruction rather than to go through the osascii or oswrch operating system routines. This is used to demonstrate the use of STA, but these programs would need altering to run properly on the Electron due to the lack of a Mode 7 screen.

Despite these points, I did enjoy the book and feel that it presents a reasonable survey of an area of computer application that is rather neglected by the computer book publishers. The publisher, Edward Arnold, is known for its text-books, and I get the impression that this is, at least in part, aimed at schools, where I feel that guidance from teachers would be on hand to help pupils through the practicalities of building circuits.

The chapters on machine code are particularly good as a general introduction to the basic 6502 instructions - certainly enough to allow the newcomer to sit down with a more specific Electron oriented book with more confidence.

It will help typical Electron User readers to get started on control, particularly if they have never had any contact with the subject. But when tackling the practical side be prepared to get a simple electronics book or a more experienced friend to help you out.