[Simh] VAX DZ terminal controller unit?

Bucher, Andreas (Andreas)** CTR ** andreas.bucher at alcatel-lucent.com
Mon May 23 05:34:58 EDT 2011


Hi, 

thanks for your new ideas as well :-)

The behaviour you described reminded me to the time when working with "real" hardware, especially the one when connecting two VAX's lines together ... and about the VT teminal connections, I remember that we used to "hard-wire" DTR jumpers for some machines, or doing other tricks (like unplugging the terminals to disconnect), because the "smart operators did not set up the lines correctly", as we used to say (750 and 6xxx and 8xxx models).

Like Gary did and mentioned, I remember having later (when I became operator, hehe) figured out a SET TERM config that solved those issues, and having put it into the system startup procedure of each VAX I maintained. Pity I didn't archive this file off the last "real" VAX before I did shut it down. It should be pretty similar to what was listed by him.

Nowadays, I use and fire up SIMH only occasionally, to test or verify some older software, so I didn't care too much about the DZ telnet "issue" - usually, I use the console only, and shut down when the job is done.

Actually, im my VAX.INI, I did set VH disable, to save some ressources :-)

Now, I changed that, disabling DZ and using the VH device(s) instead - works like a charm ! That's what I was used to: Log off, hit ENTER and get the login prompt again immediately. 

Btw, what I was wondering - it gives me 4 units with 8 ports each =32 TX devices, I thought I could disable 3 of them: 
simh> set vh1 disable
Command not allowed
I thought the VH is 4 separate devices, which can be disabled independently ?


> It seems there are a lot of undocumented hints, kinks, and pitfalls.

Perhaps not, it just "works as designed" - only, nobody knows how it was designed :-)

Regards,
Andreas

> -----Original Message-----
> From: simh-bounces at trailing-edge.com 
> [mailto:simh-bounces at trailing-edge.com] On Behalf Of Gary Lee Phillips
> Sent: Saturday, May 21, 2011 10:46 PM
> To: Mark Pizzolato - Info Comm
> Cc: simh at trailing-edge.com
> Subject: Re: [Simh] VAX DZ terminal controller unit?
> 
> 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
> >
> >
> >
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