Honneywell multics? from panels. the inline phots in this message folks -smecc

Charles Anthony charles.unix.pro at gmail.com
Sat Mar 12 12:33:42 CST 2016

On Sat, Mar 12, 2016 at 10:27 AM, Dave Wade <dave.g4ugm at gmail.com> wrote:

> Copied back to the main list….
> OK on the L66 machines I worked on we always kept the doors closed, there
> was an application, can’t remember its name, we ran on a VDU by the system
> console that displayed the Job Queues, State of Active Jobs, CPU
> utilization etc. There was also a MIPS meter on the console. They were very
> modular, and as the store was in the SCU’s on a multi-cpu system you also
> needed cross coupled cache cables to invalidate the CPU cache when the
> other CPU overwrote a word in main sore that it also had cached.

I think the cross-coupled cache cables post-date the code and documentation
I have; I believe that Multics does a inter-CPU interrupts to do cache

SInce the emulator doesn't implement the WAM cache, cache coherency isn't a
problem, and one of my low priority projects is determining if Multics can
use the knowledge of no-caching to to reduce overhead. (Ie. don't signal
invalid cache.)

> Interleave was also interesting, so you could configure interleave memory
> word by word so alternate accesses went to the “other” SCU. A guy we had in
> at NERC Bidston (was www.pol.ac.uk), Vince Martin I think his name was
> who had worked in the Honeywell performance labs, I believe in Scottsville.
> Arizona said this would give much better performance. He also said the big
> bottle neck on the L66 was memory bandwidth. With the fast 6250 BPI tapes
> he said the tape drives could drive the memory flat out, locking the CPU
> out….
I believe that.

-- Charles

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