[Simh] What is CDC OS?

[Timothe Litt]

On 16-Feb-16 16:04, Nelson H. F. Beebe wrote:
> Will Senn <will.senn at gmail.com> asks on the list on Tue, 16 Feb 2016
> 12:47:12 -0600 about CDC operating systems.
>
>
> The CDC [67]x00 family CPUs have no interrupts: instead, there are
> several peripheral processors (PP's) that interface to external
> devices such as disks and serial terminal lines.  The PP's are 12-bit
> computers, each with 4096 words of memory. They communicate with the
> main CPU by monitoring a couple of privileged memory locations that
> hold data for a device operation.  At our site, the PPs were never
> accessible to end users, so no one outside the computer center ever
> knew their instruction set.
>
>
http://ygdes.com/CDC/60141900_Codes_Rev-A_May65.pdf

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