[Simh] Additional Interfaces for the VAX780 simulator

[Ethan Dicks]

On 4/14/09, Hölscher <hoelscher-kirchbrak at freenet.de> wrote:
> I would like to have two (or more) additional interfaces for the VAX780 simulator:
>
>  DMC-11 (for DDCMP - DECnet, would be useful for the PDP-11 as well)

How would you handle the sync-serial nature of the external interface?
 When I used to make and sell intelligent serial boards for bisync
communications (HASP, 3780), we used the COM5025 USART because it was
used on DEC boards from the 1970s (and our product was originally
hosted on a PDP-11), then we moved to the Zilog Z8530.  Modern
machines have nothing like that (the Z8530 appeared in the old Macs
and SPARCstations, but not any Intel-based machines unless you added,
say, a Localtalk card).

Emulating the DMC-11 at a register level is probably not so hard, but
how do you plumb the data off the hosting machine?

>  Anyone else interested in those devices, or am I the only one?

It could be an interesting device to have if you could get around the
external interface issue.  In the meantime, at least with VMS (not
sure about PDP-11 operating systems), what about async DDCMP?  Are you
working in an environment where that's not possible?

-ethan