I was staggered when Toni first brought the manuscript for this book to us at the National ZX80 and ZX81 Users' Club. We'd talked about it, and Toni had given me a broad idea of the contents of the book, but until I had the chance to read it, I did not realise just what a comprehensive and easy-to-understand work it would be.
The book has been written for those who know BASIC, but haven't much idea about machine code, and want to get down and master this most useful addition to one's programming skills. We've waited for over a year for a book like this, and now it is here.
If you've decided that GUESS MY NUMBER and SIMON are OK for a while, but now it's time to start exploring the full potential of your computer, and time to begin developing all your potential programming skills, then this book may well prove [to be] just what you've been waiting for.
When Toni first came to us with the idea for the book, I stressed that it must be designed to lead someone who knew absolutely nothing about machine code through from the true basics to the point where they would have a real knowledge of how to use it. I'm pleased to say that she has done just that, and if you work through the book with your ZX81 or ZX80 turned on, entering the programs and routines as instructed, you'll certainly end up Mastering Machine Code on Your ZX81 or ZX80.
Tim Hartnell, National ZX80 and ZX81 Users' Club, London, August 1981