MicroVAX 3100 Questions.

From: Antonio Carlini <a.carlini_at_ntlworld.com>
Date: Sat Dec 4 17:10:50 2004

> Today at auction I acquired a MicroVAX 3100 system. It's my first VAX
> hardware.

Once the bug bites, it won't be your last!

> 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.

The tape is a TZ30. Basically a SCSI TK50, so anything you read
about the TK50 probably applies. They're not as bad as people
make out. Obviously 95MB does not go too far these days. But since
almost all applicable Oses will support this tape bott media
(and it is bootable from the console) I would keep it around if I
were you.

> 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?

Yes. Since the memory is a stack of cards rather than a
set of sticks, it must be a MicroVAX 3100 Model 10 or 10e or 20 or 20e.

The difference between the 10 and 20 is the size of the case:
the Model 10 has one internal tray on which you can mount drives,
the 20 hase two. Your picture looks like a 10.

Assuming that that is so, then you either have a Model 10 or
a Model 10e. The 10e is slightly later and maybe half as fast
again (don't get exceited :-)).

If you hook up a console and power up you can tell the
difference. A Model 10 will report itself as being a
KA41-A, a Model 10e will report itself as being a KA41-D.
My guess would be a Model 10 as these are far more common.

(Note: a 20 or 20e will report the same things: the 10/20
distinction is *only* the box it comes in).

> 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.

Yes. Best to use on of the DEC ones since you will be able to
boot off it. OpenVMS, at least, cares. I do not recall whether the
console itself cares (so you might be able to boot into Ultrix
or one of the BSDs etc. with any old CDROM). If you cannot get
an RRD42 (or better), look for one which supports 512-byte blocks.

> 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?

Ultrix will run on these, as will NetBSD. OpenVMS will also run on it,
but the maximum memory you can put in is 32MB, which might be a
bit limiting.

> 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.

No video. For that you need a VAXstation 3100 of some flavour.

I should remember whether it is the rightmost or leftmost MMJ that
provides the console, but I don't :-0. 9600, 8 NONE should set you
on your way.

BTW: IIRC the three upper connectors from left to right are
[4-11] asynch comms (probably a DHW42 - needs a cable to bring out
the umpteen terminal ports), [B1] a synch port (I used to support
the software for these!) and the external SCSI connector [diamond].

> 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.


> 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.

Manx will find pretty much everything you need.

Antonio Carlini arcarlini_at_iee.org
Received on Sat Dec 04 2004 - 17:10:50 GMT

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