[Simh] VAX DZ terminal controller unit?

[Gary Lee Phillips]

Amusingly enough, when I disable the DZ, then the VAX has 32 TXnn
terminals. But after setting the four VH units to MODEM and HANGUP in
SIMH, performance is much better.

It seems there are a lot of undocumented hints, kinks, and pitfalls.
But at least it's now functional for my current purposes, so thanks to
everyone who helped.

--Gary

On Sat, May 21, 2011 at 12:38 PM, Mark Pizzolato - Info Comm
<Mark at infocomm.com> wrote:
> On Saturday, May 21, 2011 at 8:29 AM, Gary Lee Phillips  wrote:
>> OK, interesting. Here's what I learned by trying the "VH" device
> (that's a
>> DHV11, right?)
>>
>> Though it is supposed to represent 8 lines, it created 16 terminal
> devices in
>> VMS. There are 8 TTnn devices and 8 TXnn devices. I believe these are
> all
>> programmed I/O, so the load on the processor increases as it has to
> poll all
>> those ports. There does seem to be a noticeable slowdown in response.
>
> The TTnn devices are the DZ devices which are enabled by default.
> Use:
>
>    Sim> set dz disabled
>
> To turn them off...
>
> While you are disabling the DZ devices, you can also disable any other
> devices you aren't using...
>
> - Mark
>
>
>