How do you obtain Xinu??

[Bruce Freeman]

I would like to obtan the source code for the Xinu operating system as
described in the book by Douglas Comer. Unfortunately the book only says
the software is available for a nominal fee. I would like to know where
do I get the software from (Bell? Prentice-Hall? Purdue? ...) and exactly
how much "nominal" is these days ...

Thanks in advance
-- 
Bruce Freeman	University of Toronto	{decvax|harpo|floyd}!utcsstat!bjf