not rating as it's a textbook. but i read it more for the nostalgia value of the old computers and for that it's great. ;)

I'm having some mixed feelings: on one hand, this is a very detailed treatment of 4.3BSD design, with interesting tidbits about various algorithms and the tradeoffs made. On the other, sometimes it was like someone reading the source to you -- the perfect cure for insomnia.

I was with it through the kernel proper--fifteen years of OS kernel employment made this a light task--and then hit the wall when going into the storage and network/IPC subsystems, which I know less about and have limited interest in (especially when it went into optimal placement of data in the disk cylinder for rotational latency purposes, which is file system stuff that smart controller/disk technology has passed by).

The book is entirely geared towards the VAX, to the point of discussing the UNIBUS and MASSBUS architectures. The most one can glean for other implementations is the phrase "other architectures may do this differently."

Despite its textbootk format, this is not an introductory primer for operating system design. It is more useful as a reference, to see how certain problems were tackled. The modern version might work as a textbook for a subsequent OS course.