MicroVAX 3100 Questions.

From: Patrick Finnegan <pat_at_computer-refuge.org>
Date: Sat Dec 4 17:13:07 2004

On Saturday 04 December 2004 17:43, Scott Stevens wrote:
> Today at auction I acquired a MicroVAX 3100 system. It's my first
> VAX hardware.

Ahh, you're the guy... I was only interested in making sure it didn't
get scrapped for parts, really. Anyways, I'm glad it went to someone
who'll appreciate it. I was afraid it was just a clueless idiot, who'd
get it home, figure out what it is, and then throw it out, but it seems
my worries are unfounded. : ) There seemed to be a lot of those there
after the Cisco gear today.

> I don't know a lot about it and thought I would ask here for help.

I'll see what I can do.

> I put up a picture of the system on some personal webspace. The page
> is: http://sasteven.multics.org/MicroVAX/MicroVAX3100.html
> The system is a low-profile box, with one opening in the front face
> with a 5-1/4" form factor tape drive presently installed. There are
> free connectors and space inside for a single narrow SCSI drive. The
> system has two mezzazine-mounted memory cards inside and appears to
> have 16 megs of RAM on the cards.

Not too bad for a VAX.

> The model plate on back (one of the pictures on the page I put up)
> reads:
> Model- DV031DTA-A - A01
> S/N- KA324TJ182
> Some questions:
> 1. I notice on the Web that there is quite a bit of info about
> MicroVAX 3100 systems. I also see that there are a variety of
> models. Is there an easy way to figure out which one I have?

I can tell you it's either an M20, M20e, or M40. My guess, since it's
not labelled which model, would be an M20, which has 2.4 VUPS. And,
fairly nice, as it uses nice, cheap SCSI disks.

> 2. Would it be possible and/or work to replace the tape drive with a
> SCSI CD-ROM reader? I don't have a source for tapes.

You should be able to, but you'll need the proper CDROM drive. I've had
good luck with the 1" tall cdroms in Sparcstation 5's and 10's, which
is basically the same as an RRD42. If you don't have any let me know,
I've got some stock of them.

> 3. Is it worth putting VMS on this box? It looks like it could run
> NetBSD as well. I also have McKusik's BSD archive CD set that he
> sells. Is there a flavor of vintage UNIX that I could put on the
> system?

VMS would run decently on that, you could run 7.2/7.3 even, as it has
plenty of RAM.

> 4. What is the console on this hardware? It has the three serial
> ports on RJ-type connectors, and from what I gather this is a
> TTY-only machine, no framebuffer, etc.

Should be the MMJ connector labelled "3" IIRC. If want a proper MMJ
cable, I've made them for people on the list before. If not, a piece
of 4pr phone cable with the tab filed/cut off should be able to connect
it to an RJ45->DE9 or DB25 adaptor properly. Xyplex, Sun, and
Cisco-wired adaptors should all work with it. If you want a pinout,
search google for "xyplex pinout" and hit I'm Feeling Lucky.

> 5. Is there a thorough hardware reference for this machine out there
> on the net that I should get? I looked on the HP/Compaq site, and it
> appears that they pay a small amount of homage to the system, but
> without much substancial info. A hardware reference manual in PDF
> would be great.

Try bitsavers (or, since it's currently down, my mirror at

> Any and all info would be appreciated. If there's a good site that I
> should be pointed to (there seems to be tons and tons of info out
> there, which results in Google pulling up a huge mass of stuff to
> weed through) instead of answering these specific questions, a
> pointer to it would be appreciated.

Hmm. Compaq's openvms doc site is good for VMS documentation (free PDFs
and HTML versions) at http://www.openvms.compaq.com:8000/

For other info, either looking at bitsavers or google should work well.

Purdue University ITAP/RCS        ---  http://www.itap.purdue.edu/rcs/
The Computer Refuge               ---  http://computer-refuge.org
Received on Sat Dec 04 2004 - 17:13:07 GMT

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