[Simh] VAX DZ terminal controller unit?

Gary Lee Phillips tivo.overo at gmail.com
Thu May 19 12:59:22 EDT 2011


I'm running SIMH 3.8 on Ubuntu 10.04 with OpenVMS 7.3 from the OpenVMS
Hobbyist CD.

The emulation seems to be working well for almost everything I've
tried, except that using the DZ device causes some odd behavior.

In my vax.ini file I have:

SET DZ LINES=8
ATTACH DZ 8501

When the VAX emulation is booted, it is possible to "telnet localhost
8501" (or use a telnet client from another machine to port 8501 on the
emulation host) and get a login prompt. This works as expected for one
session. However, after logging out it is no longer possible to
connect again. When I try, I get as far as

Connected to the VAX simulator DZ device, line 0

But pressing ENTER or CTRL-P or any other key never brings up a login
prompt. Sometimes after a few minutes it will work again, but not
always. If I leave the "dead" session connected and try to start
another instance of the telnet client, that connects to "line 1" and
works, but once it is logged out, line 1 is no longer usable. And so
forth...

Something is not being reinitialized. I've tried "logout/hangup" and
"logout/nohangup" and using the telnet client to send break signals
and other out-of-band communications, but nothing seems to revive the
line.

I may well be missing something here. Any advice?

Note that with TCP/IP installed and working on the OpenVMS system, a
standard telnet connection to the emulator still works correctly, but
this doesn't allow a terminal connection from the emulator host
machine itself. It only works from another machine since both IP
addresses are hosted on a single NIC in the emulator host.

Thanks for any help you might offer.

Gary



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