DEC MicroVAX question

[Moondog]

I recently un-earthed a DEC MicroVAX 3100-90 with a VT-420 terminal.  The crt on the VT-420 appears to be dead.  The terminal used to connect to a port similar to an RJ11 connector, however I was wondering if it's feasible to connect to a serial port and use Hyperterminal or similar application?  The VAX had a Decmodem connected, which I'm guessing was used for remote communication.

[RedWolf]

I recently un-earthed a DEC MicroVAX 3100-90 with a VT-420 terminal.  The crt on the VT-420 appears to be dead.  The terminal used to connect to a port similar to an RJ11 connector, however I was wondering if it's feasible to connect to a serial port and use Hyperterminal or similar application?  The VAX had a Decmodem connected, which I'm guessing was used for remote communication.

Cool find!

It's likely the RJ-11 jack is simply an RS-232 port, so if you figure out the pinout, you can make an adapter for it.

But wait -- what does the other end of the cable look like -- the one that plugs into the VT-420?  If it's a D-type connector (DB-25, etc.), then you can probably connect it directly to the serial port on a PC (you might need a DB-25 to DE-9 adapter though if you have a, say, post-1995 PC).

You'll have to know the baud rate to connect properly, but even if you can't figure that out on the DEC end (via rotary switch or dip switch settings), then it's not hard to try 300, 2400, 9600, 19200, 56700, etc. until one works.

Exciting, overall! Let us know how it goes.

[RedWolf]

I just found the description of the DEC-423 connector, which is probably the connection you're talking about:

http://vt100.net/dec/vt320/serial_connections

According to that page, you should be able to build a DEC-423 to RS-232 adapter if you follow that pinout.

DEC-423 is compatible with EIA-232 interfaces for connections employing data lines only.

By the way, I found the VT420 user guide here:
http://vt100.net/docs/vt420-ps/vt420ps2.pdf

Hope that helps.

[Moondog]

That's the connector the terminal uses, but there's also a D25 RS-232 connector on the back.  I made some phone calls and found DEC/ VMS guy who has a terminal to connect to it, so it's more of an academic question than anything else.  The guy is in agreement, that the modem that was connected to it was used to remotely access the system, so it may be possible to connect a pc to the serial port and use Hyperterminal.

[RedWolf]

I'm slightly confused now.  The VAX was connected to a modem -- through what connector?  A DB-25 or that 6-pin DEC-423 thing?  I guess I didn't realize that part of your post.

If a modem is connected to the VAX, it's definitely a serial port, so you can likely hook a terminal directly up to it with the right cable, although the software might have to be configured to understand it as such.  Unless, of course, the VAX has a dedicated "console" serial port, which should always work for any serial terminal.  I've never used VAXen of any kind, but I have a few MicroPDP-11's and they always have console ports.

Keep us updated.  Could you post some pictures of your find?

[Moondog]

It had both a DB25 (which the modem was connected to) and the DEC terminal port.  Our resident DEC VMS/VAX guy was saying the 25 pin serial port could be used if it was configured before, which was a good bet if that's what the modem was being used for.

I am currently without a good still camera, but I plan to pick up another as the holiday deals appear.  For now, I can describe it.  It's tan and about the size of a standard ATX case, but in a desktop (sideways tower) layout.  In the front there's a swing open door that hides a removable drive bay, similar to the old Syquest drives.  On the back there is the DEC terminal port, the DB25 serial port, another DB25 port with a dongle plugged into it, and a SCSI connector which looks like an oversized Centronics port.

[Moondog]

Our VMS/ Dec guy checked it out today and said the hard drive that has the OS on it is dead.  It has two other had drives installed, so he can mount those drives in another VAX and pull files from it.

[RedWolf]

Our VMS/ Dec guy checked it out today and said the hard drive that has the OS on it is dead.  It has two other had drives installed, so he can mount those drives in another VAX and pull files from it.

Cool.  I'm glad you have a DEC guy on hand to help you with that stuff.  Those systems can arcane and challenging to work with.  Please keep us updated.

Any plans on what you're going to do with the thing once you get it running?  What OS will you put on it?

[Moondog]

It's out of my hands now.  Once the previous owner gets what they want off it, it goes to the DEC/VMS guy for spare parts.  My understanding is there's power plants and steel mills that still have these old systems in use, but because they are so reliable, they are kept in place.  They were also very pricey when brand new, most places are afraid to look at the cost of developing a replacement plan for them.

If I was to keep it, I doubt I'd run it as is.  I've seen some case mods done with them, but it's too plain Jane and I doubt very many people know enough about old Dec machines to use it as a conversation piece.

I once had a chance to salvage an IBM RS-6000 cabinet, and thought it would be cool to gut it out and put a mini-fridge or liquor cabinet behind the facade.

[lucidphreak]

would be neat to have a "play around" vax online... the only ones ive been on I wasnt supposed to be so I didnt loiter long after getting in...

[Moondog]

would be neat to have a "play around" vax online... the only ones ive been on I wasnt supposed to be so I didnt loiter long after getting in...

Are you familiar with VMS, decnet, and all that stuff, or are you just a user?  I've set up the Pathworks protocol on Windows machines so they can emulate terminal sessions, but never dealt directly with them.