Interesting blend of history/people and technology.
I was looking for an overview of the Spectrum hardware (I did not have one back in the day) and where the ULA fitted in to that (Ferranti also did the ULA for the Acorn Electron) and this book hit the nail on the head for me. I particularly wanted to know how the graphics on the machine worked.
Some of it way over my head, but the information I was looking for was definitely there and explained well. Short chapters, so easy to skim the technical detail I wasn't interested in and get back into my comfort zone, and didn't feel there was unnecessary padding.
Criticisms - minor one - I think the second chapter - very low-level detail on integrated circuits - might have been better placed at the end of the book or as an appendix. For me it was really heavy going for such an early chapter and it didn't get the book off to a good start ... but I persevered and it swiftly picked up in chapter 3 onwards.
Not sure I would be able to "design a microcomputer" after reading this book, but definitely a good read from a programmer's perspective.
I read this excellent book over the course of a week's camping trip on the Isle of Wight this summer.
In short; it has been a long time since I have read a technical book with as much enjoyment. Concise, consistently interesting and intelligently organized - I have recommended it to several of my retro-computing inclined colleagues. My fiancée was giving me odd looks throughout the camping trip as I was reading it since I kept saying things like "aha! So *that's* why that's there!" at regular intervals.
Highly recommended to anyone with a technical interest in the ZX Spectrum! :)
This is not only one of the best books I have read about the ZX Spectrum from the technical side, but it is one of the most interesting books on how a microcomputer was built in the early years. It is very detailed, has plenty of diagrams and shows many little known secrets hidden within our beloved ZX Spectrum. I would recommend this book to anyone having had a ZX Sinclair, be it the Spectrum or even the ZX81 or ZX80.
The book has a curious mix of material. Some will undoubtedly be known by anyone interested in the subject, such as the sketchy overview of the Z-80 or of the ZX Spectrum as a whole, while other parts assume you know what a transistor or logic gate is. Other bits aren't necessary, for example how various sorts of transistors are created on the layers of silicon.
But the main bit of the book is both fascinating and unique, and travels back to a time when Britain led the world. Chip design from scratch can be painfully slow and expensive. So what the British company Ferranti developed was an array - a square or rectangular grid - of cells of unconnected transistors, resistors etc. Anyone wanting a quick and cheap 'chip' only needed to specify how those were to be connected together, just one layer of the silicon. Join a pair of transistors in a cell one way, and you have a 'NOR' gate; join three in another cell another way and you've something else; join the two cells together and you've got a more complicated circuit...
For a company like Sinclair, trying to reduce the component cost of their microcomputers, these were a godsend. The enabled the number of chips inside its ZX81 to be just four (Z-80 CPU, 1k RAM, 8k ROM and ULA) rather than the more than a dozen of its predecessor, the ZX80. So when the ZX82 - later renamed the ZX Spectrum - was being designed, it was an obvious move to use a larger ULA to get as much of the circuitry onto a single chip as possible.
This book is the story of who did that, what they did, and the very few things they didn't quite get right.