November 8, 2016


Xinu is an operating system written by Douglas Comer. It has quite a history, going back to DEC minicomputers. The original version was written for the DEC PDP-11 in 1979. It has since been ported to many systems, including the Sun2, sun3, vax, spacstation, x86 and more. Recent ports include MIPS based routers and various small ARM based boards

Xinu is small and written in a clean simple style, which makes it ideal for studying and learning about operating systems. It has been polished over many years and emphasizes clarity, presumably since it is heavily used as a teaching tool.

The "real Xinu" project on Github is the "real thing", i.e. the sources currently being maintained by the Xinu inventor, Douglas Comer at the Purdue University computer science department.

There is another Xinu project on GitHub called "Embedded Xinu". I have not worked with this and am unsure of what hardware it runs on. As I understand things, this project is being done by one of professor Comer's former students.

There are a pair of Xinu books:

Book 1 emphasizes the operating system and book 2 emphasizes networking. If you are a cheapskate like me, you can buy the original edition (which discusses code that runs (or ran) on the PDP-11). This is not as bad as it sounds as the bulk of the code is portable C and with the current sources for the BBB, you are in great shape. Besides that, the PDP-11 is simple enough and entertaining to learn the details of. You could get carried away and find a PDP-11 emulator somewhere. Then with in-depth knowledge of the PDP-11, you would be in great shape to tackle the classic "Lions Commentary" on Edition 6 Unix.

Currently active Xinu projects

My interest in Xinu began with the BBB, which is a small ARM based single board computer. Subsequently I have gotten involved helping port Xinu to the Orange Pi, which is another extremely inexpensive (and multi-core) ARM based board.

Feedback? Questions? Drop me a line!

Tom's Computer Info /