[comp.arch] CDC NOS vs. Mainframe channels vs. DMA vs. NeXT

smryan@garth.UUCP (Steven Ryan) (11/01/88)

>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.