It was fascinating to read this book from 1979 and see how operating system design was viewed then, compared to now. The biggest change being the shift in importance from batch processing to the interactive use of computers. Despite the advances since this book was written, it is surprising how many themes are just as relevant.
I loved the comparisons between the different mainframes and minis of the day, such as the PDP-11 and IBM 370 series, and how various functions were implemented in their operating systems. This book gives you a really good insight into the relatively early days of operating systems, so that you can better understand how we got to where we are now.
While covering issues such as Virtual Memory, Memory Management, Concurrent Processing, File Systems and Resource Allocation the author discusses differing approaches which makes for interesting reading as there was no agreed consensus, as to the best strategy, at that time.
This book is still useful if you want to understand the basics of operating systems design, but is of real interest to the computer historian, who will find a wealth of information in an easy to understand format.