[Simh] VAX 8200/8250

[Matt Burke]

On 06/04/2019 21:28, Timothy Stark wrote:
> I was surprised to see that!  Very good news!!  Good job!  I will try that soon.
>
> For 8250/8350, you need two MP processors.  Does vax820 emulate two MP processors like VAX-11/782?
>
No, but I have got another branch which does. It's a fairly nasty hack
just to test the theory. Basically the two processors are run in
lock-step and it saves/restores the context of each CPU between
instruction cycles. There's a lot of overhead in that so the performance
is quite poor once you start the secondary CPU.

Bob Supnik created a simulator for the SiCortex SC1 several years ago
which shows a better way to do multiple processors in lock-step but that
would involve significant changes to the VAX CPU and MMU modules.

Matt