[Simh] Additional Interfaces for the VAX780 simulator

[Gregg Levine]

On Tue, Apr 14, 2009 at 9:36 AM, Ethan Dicks <ethan.dicks at gmail.com> wrote:
> 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
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Hello!
Well actually I am, Ethan. Especially the DDCMP connection.

I am still curious if the connections posing as a serial one can be
connected to a physical device. I believe the Altair/Imsai one can be
connected to one such device, but I've also never had a reason to try
it.

-----
Gregg C Levine gregg.drwho8 at gmail.com
"This signature was once found posting rude
 messages in English in the Moscow subway."