If you haven't used machine code on your Dragon before, then this is a helpful start to the (often tricky) subject. The only real worry is that, by the time you're really getting to grips with the 6809, the book is more a source of frustration than enlightenment. However, once you've read this book, you'll be able to understand most of the available books on 6809 programming, and more importantly, you'll be able to understand them with reference to your Dragon.

The sections of the book dealing with how to get into machine code at all, and on how to get the best from your Dragon, are very good. They will get you to the point of seeing what a machine code routine looks like, and towards getting them out of magazines and books and into your machine.

The very fact that the book becomes increasingly frustrating is a tribute to the way the author takes the reader, step by step, into machine code. By the time you've finished the book, you will be eager to get into some of the more technical, and until you've read this less accessible, books on the 6809 assembler.

However, this is the first book that I've seen about machine code which is very instructive about how to use it on the Dragon. Many machine code books are too "head in the clouds" for home users.

A little more expensive than most computing books, but I still think good value for money (still around the same price as a piece of software).