[Simh] Configuring DMC11 Devices

[Mark Pizzolato]

On Monday, January 4, 2016 at 12:06 PM, Paul Koning wrote:
> > On Jan 4, 2016, at 2:53 PM, Mark Pizzolato <Mark at infocomm.com> wrote:
> >
> >> ...
> >
> > I vaguely remember that something else depends on how it is currently
> > implemented.  The wait delay was added to accommodate the fact that
> > something didn't expect immediate response.  A delay of 1 is essentially the
> > same as no delay.
> >
> > It is hard to imagine that the OS driver would expect that the device would
> > complete some operation in one instruction time.  This would tend to fail as
> > newer models of CPU were implemented which used the same peripheral
> > hardware, no?
> 
> All I can say is that it does work on real hardware.
> 
> The manual says that the bit is "self-clearing".  That isn't the same words as
> the more common "write only" but it implies roughly the same thing.  The
> driver definitely does not expect the whole master clear process to complete
> in a few instruction times; it patiently waits for RUN to become set.  But it
> DOES expect that MCLR does not read back as set, not even very quickly
> after it was set by the driver.
> 
> So maybe the thing to do is have the process master clear action be started
> at the CSR write rather than delayed (while other CSR operations can remain
> delayed) so that at least the clear_master_clear part is done right away.

Sounds reasonable.  I've got to see if I can find the reason the delay was 
initially added and make sure a change like this is compatible.

> >> By the way, if I connect a DMC to a DMR, it doesn't come up.  Is that
> >> expected?  I thought DMC and DMR were sufficiently compatible that it
> >> would work...
> >
> > They absolutely should work as long as the both get turned on by software.
> > The wire protocol is the same.  The wire protocol is also compatible to host
> > based DDCMP protocol implementations on the PDP10 and RSX since it can
> > reliably talk to KMC/DUP configurations.
> 
> Ok, that's what I figured.  The wire protocols in the real hardware are actually
> not identical (DDCMP 3.1 vs. DDCMP 4.0, and in the case of the "high speed"
> DMC-11, 3.1 with some bugs that I might still have documented somewhere).
> But yes, they are supposed to be interoperable.

I still need a RSTS disk image and configuration file which has several DMC/DMR's 
configured and attempts to start the network....


Thanks.

- Mark