An important two-volume series, the first volume describes each step of the design and decision making process, while Volume II adds internetworking and user interface software. Professional software programmers can learn how protocol software fits into an operating system and how VAX software works as well.
I had been doing system programming for a few years, read several books about operating systems, and written a couple of device drivers for UNIX before I encountered this book. I was comfortable working on existing operating systems, but writing a complete operating system seems like it would be overwhelming. Reading Xinu, and later doing labs on a PDP-11? gave me confidence to take on much more challenging projects and led me to conclude that if I needed to, I could write an OS from the ground up.