itsy bitsy Unix

Huw Davies huw.davies at
Fri Mar 18 01:18:24 CST 2005

Well moving back on-topic a little....

I would have thought that there were a number of timesharing operating  
systems written for the PDP-11 above and beyond those written by DEC.  
The reason being that -11s were relatively cheap and the architecture  
isn't too bad compared with some other architectures popular at the  
same time (ooh, I can feel the flames coming from miles away :-). Now I  
wouldn't want to write an operating system in assembler, but if you had  
to, an -11 (or even better a VAX) wouldn't be the worst choice.

I can think of two "well known" operating systems written for the -11.  
These are xinu ( and solo  
( xinu is written in  
c and solo in Concurrent Pascal.

I remember reading Per Brinch Hansen's "The Architecture of Concurrent  
Programs", which includes the complete program text of the Solo  
operating system and suddenly all the concepts of operating system  
design I had were crystalized into knowledge. Another book on my list  
of "need to finds"....

Another (even more interesting) operating system is Hydra written for  
the CMU* "Beowulf" of PDP-11s. See 

Huw Davies           | e-mail: Huw.Davies at
Melbourne            | "If soccer was meant to be played in the
Australia            | air, the sky would be painted green"

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