This book is full of facts, it is useful, as a supplementary text book. It is legendary in it's covering of stuff like floating point form, and other binary arithmetic such as BCD(Binary coded decimal) arithmetic. You certainly cannot use this book alone though, as it doesn't cover a syllabus like A level, it's too general for that. If you want lists of things, then it's good, it's very definitive that way. It has diagrams too.
BUT BEWARE, on one page there is a mistake where it puts the MBR in main memory and doesn't mention that the MBR and MDR are the same thing. (I am talking about registers in the processor) But otherwise it's fairly authoritative.