This book focuses exclusively on XINU, the OS written mainly by Comer. I will say this book is useful in the time when there was no open source, decent OS, however with the advent of Linux, I can't see any reason to study XINU anymore. Although XINU has most of the functions a modern OS should possess, there is essentially NO application written for this OS and it is only used by a handful of universities in their OS courses(for example, Purdue University, WL). If you really want to learn OS, I would recommend you to learn Linux which has relatively superior documentations(and is far more useful and stable than XINU). Some universities also used other experimental OSs like Nachos. I know nothing much on these OSs, therefore I make no comments.

Some people might argue Linux is far too complex and intimidating for beginners to study, well this is true in view of the current Linux kernel, however the instructor should be able to remove the superfluous components in the kernel. The basic kernel is not hard to comprehend at all.

Disappointing but informative...I take back that statement.

Rating: 4/5

For the most part this book is informative. If you have no idea of how a basic Operating System functions, or what it's responsibilities are, then this book will definitely clue you in. However, this book seemed to fall short of what the writers promised. For example, the version of XINU described in this book boots from DOS. I am suspicious of any operating system that boots from another operating system and then uses the services of it...it reminds me of Microsoft Windows 3.1. The OS also uses and relies on some of the PC's BIOS routines and services. While that technique makes the OS portable on different PCs, it limits its use only to PCs and hides a lot of operations that (in my opinion) should be shown. After reading it a few times, I found that the book was quite helpful after all. The OS has been ported to many other CPU's. The full source code can be found on the internet. The OS is quite powerful but still is simple (I was able to port the code to run on a 68010 project of mine; seeing the ported versions and the book's theory was enough to guide me). A decent book, it doesn't describe an operating system 'from the ground up', but comes close to it. Sure there are other operating systems out there with open source, but how many of those tell you what each function of the code does and what role these functions play in a OS?

Great book to learn Operating System

Rating: 5/5

Xinu is a beautiful OS and this book is a very
readable description of Xinu. Xinu with its threads
and micro kernel architecture is very suitable for
embedded applications and it has TCP/IP stack too.
Xinu is not a toy OS or even merely an
educational OS. I personally ported Xinu to an R3041
(MIPS) based board for an industrial application and
it worked very well. Hats off to Comer and others at
Purdue for giving Xinu to the world.