Four of the chapters in this book deal with techniques, the remaining four cover background topics such as the 6502 instruction set, the hardware and the resident assembler. Techniques discussed include: multi-byte loops, sort routines, subroutines, macros, look-up tables and graphics and interrupt handling. While these techniques are quite advanced the book is aimed more at the early enthusiast, and also contains basic information.
It's written in a clear and easy-to-read style, the authors steering that difficult course between long words and convoluted explanations and three-letter words and cartoons.
My main criticism is that while addition and subtraction (of integers) get a good airing, multiplication and division are hardly mentioned. It could be argued that a work covering advanced techniques should not include such mundane items, but then why do such basics as the 6502 instruction set get a 25-page chapter and a 14-page appendix?
The chapter on interrupts is a little confusing and, for owners of the standard Electron, largely redundant, since it deals mainly with the 6522 user VIA which the Electron does not possess. The brief section in this chapter devoted to interrupts is spoiled by the omission of the interrupt-handling routine from the only example program.
I do not want to give the impression that I didn't like the book, on the contrary, I enjoyed reading it very much. It's one of the few books which has a comprehensible and interesting description of the hardware, plus an explanation of the speed difference between the Electron and the BBC, which use the same processor but different memory configurations.
However, the description of the 6522 VIA's registers - which seems almost compulsory these days - left me glassy-eyed as usual. I'm sure that setting low order latches is crucial stuff but I'm still waiting to find out why. Am I alone? Regurgitated data sheets from chip manufacturers do not make good educational material. It would be helpful if we were given a bit more information on the why rather than the what.
A useful and instructive book for people who are just past the beginner stage and want to stretch their wings.
1st December 1984
