Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!amdcad!ames!mailrus!cornell!uw-beaver!teknowledge-vaxc!sri-unix!garth!smryan
From: smryan@garth.UUCP (Steven Ryan)
Newsgroups: comp.arch
Subject: CDC NOS vs. Mainframe channels  vs.  DMA  vs.  NeXT
Message-ID: <1694@garth.UUCP>
Date: 31 Oct 88 23:19:49 GMT
References: <10778@reed.UUCP> <1594@scolex>
Reply-To: smryan@garth.UUCP (Steven Ryan)
Organization: INTERGRAPH (APD) -- Palo Alto, CA
Lines: 15

>and share it in rotation.  And, yes, each of the PP's is a (more or less)
>general purpose processor (people have written PacMan-like games, baseball,

On NOS, most of operating system consists PP programs that are shuttled
in and out of the PPs. NOS is interesting case of distributing a program
among a variety of dissimilar processors.

NOS/VE (180 state) has gone back to just using them as device drivers.

>memory location 0 (what?! Dereference NULL?!), the PP's scan all jobs
>location 0's, see the change, and do it.  You can optionally be suspended
>from execution while the I/O is being done.

MTR used to scan, but nowadays, the program must use an explicit
exchange jump (sorta an interrupt) to ensure the request is seen.