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Saw some microvaxes on ebay buy it now cheap

C

carangil

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Oakland, CA
http://www.ebay.com/itm/VINTAGE-DIG...081196?hash=item4659e7e82c:g:6mMAAOSwu1VW6hZM

$89 doesn't seem bad when I consider what I've seen other DEC stuff run. I've never played with a VAX or VMS, so this might be interesting. What kind of fun (or mostly pain) am I up for if I get one of these, trying to get a hard drive for it, finding a copy of VMS, and getting this thing to read some kind of media or boot off a network?
 
That sounds cheap, but you'll still need an LK201 keyboard as well as a VS-whatever mouse. The connectors, particularly the SCSI ones, can be a bit weird. So you'll want to factor all that in. No floppy, hard disk or CD-ROM.

If you're not a VMS freak, there is a BSD distro publicly available.

The 3100s used to be the most common variant--you used to be able to pick them up for next to junk value. Of course, things do change--here's a 2002-era guide
 
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I have a 3100 model 85 if I remember correctly. They used SCSI 50 pin drives and I think mine has a CDROM installed plus one HD. You need a terminal to work with them (I have a couple VT-525's with the DEC keyboards but you can use anything PS/2 with them). You also need special phone type cables between the unit and the terminal.

Never did install VMS on mine (had a full install when I got it) so I don't know how easy or hard finding media and installing it is or copy protection BS.
 
bear said:
A MicroVAX has no console framebuffer. It uses a terminal. Why would you need a mouse or LK201?
Click to expand...

Some 3100s do, such as the model 40, and I misread the description. This one looks to be a 10E, so yeah, a terminal is needed--along with the funny RJ-sortof cable. One thing does confuse me--the item description says that the CPU speed is 25 MHz, but has a KA41 CPU. Did KA41s come in 25MHz?
 
The serial cable's plug is called MMJ. Should be easily crimpable with a phone plug then breaking off the notch, but I didn't have to resort to that.

Current Net/OpenBSDs are incredibly painful, buggy and especially SLOW on VAXen (see port-vax maillist for the thread), but VMS is more interesting anyways. Or run Ultrix.
 
Chuck(G) said:
Some 3100s do, such as the model 40, and I misread the description.
Click to expand...

IIRC, the VAXstation models want a direct keyboard and monitor connection; the MicroVAX models don't. Even on the VAXstations I think you can get them to come up using a terminal on a serial port as the console.

One thing does confuse me--the item description says that the CPU speed is 25 MHz, but has a KA41 CPU. Did KA41s come in 25MHz?
Click to expand...

Pretty sure a MicroVAX 3100 model 10e is a KA41-D at 16.7 MHz. That is probably as fast as the KA41 ever shipped.
 
carangil said:
What kind of fun (or mostly pain) am I up for if I get one of these, trying to get a hard drive for it, finding a copy of VMS, and getting this thing to read some kind of media or boot off a network?
Click to expand...

As said above, a 50-pin SCSI hard drive should work. Not sure how big a disk that machine will work with, though. The one I had in 1990/91 only had an RZ23 (104MB) in it. Pretty sure it could handle a 1GB drive, but not too sure beyond that.

You can get a hobbyist VMS license for free with a bit of paperwork. Not sure what media you can find through HP or the hobbyist community. Back in the day, my unit had a TZ30 (SCSI cartridge tape drive that read/wrote TK50 media), and I had VMS 5.5-2 and 'C' on TK50 cartridges. CD-ROM or a disk image with BACKUP savesets that you could write to a spare SCSI hard disk would probably be a lot more convenient at this point. I don't know if any old SCSI CD-ROM drive will work or if you need one from DEC, but I expect that you will need to cable it using the external SCSI bus connector if you expect to use it with the box buttoned up.

The boot ROMs in that box do not know how to talk TCP/IP, so you will either need to set up a machine that can serve MOP (the DECnet-associated Maintenance and Operations Protocol) to feed it a boot image, or give up on that. The 3100/10e has both an AUI and thinwire ethernet port, so you will need a transceiver or other means (e.g. 10BASET hub with AUI port) to get it connected to a modern twisted pair ethernet network.
 
Looks like a good price!

In addition to VMS, you can run ULTRIX too. That's what I've got on my 3100.

W.R.T. MMJ connectors, I now have the Paladin dies for crimping MMJ, a 500 foot roll of 6-conductor satin cable, and a quantity of MMJ connectors. PM me if you require cables. Keep in mind that MMJ is not RS-232, but you can convert to it with IIRC a few resistors.
 
The photo of the label on the back and the description for this item listing both say DV-31ATB-A, which as far as I can tell would be a KA41-A M10 CPU (90ns), not a KA41-D M10e CPU (60ns). I couldn't be sure myself which one it is without opening the system to take a look at the part number on the motherboard, or powering up the system to see if the firmware reports a KA41-A or a KA41-D CPU.

I have a couple of the 3100 M20 version, which is the same as the M10 version except in the slightly larger case. They are fairly slow compared to any other VAX systems you might find except the MicroVAX / VAXstation II and 2000. If you don't have any VAX systems and you want to try one out they are aren't that bad of a start if the price is right and they come with the max 32MB of RAM. If you got one with just the base RAM on the motherboard you could easily spend almost as much for the somewhat rare memory expansion boards as you did for the whole CPU to max out the RAM.

The maximum supported SCSI hard drive capacity is 1GB (1,073,741,824 bytes) due to the firmware 21-bit LBA limit. You can however use larger SCSI hard drives if you soft resize the capacity down to the 1GB limit. I have done that and it works fine the the pile of 9GB drives I have.


One interesting thing that can be done with a MicroVAX 3100 M10/M10e/M20/M20e is turn it into an InfoServer 100/150 by replacing the firmware EPROMs. That is really only useful if you have other VAX systems that don't have a local CD-ROM drive which you want to boot and do a software install on over the network, or you have a VXT terminal you want to boot from an InfoServer.


If you don't already have any MMJ adapters to connect to standard DB25 ports on a terminal or PC you could pick up some of these H8571-A for $5 including shipping. That's about as cheap as I ever see those on eBay.
http://www.ebay.com/itm/131921579216


For reference:
MicroVAX 3100 / VAXserver 3100 / InfoServer 100 SYSTEMS
Illustrated Parts Breakdown
EK-A0372-IP-003
A0372IP3.PDF (http://decdoc.itsx.net/dec94mds/a0372ip3.pdf)

CPU Boards:
54-18856-01 MicroVAX 3100 Model 10 / Model 20 KA41-AA (90ns)
54-18856-02 VAXserver 3100 Model 10 / Model 20 KA41-BA (90ns)
54-18856-04 MicroVAX 3100 Model 10e / Model 20e KA41-DA (60ns)
54-18856-05 VAXserver 3100 Model 10e / Model 20e KA41-EA (60ns)
70-28103-01 InfoServer 100 KA41-CA
54-18856-06 InfoServer 150
 
That's a really good price on DB25 MMJ converters. IIRC MMJ is some sort of balanced pair thing like RS-485, so you can convert to RS-232 with a few resistors. I've heard of people crimping a RJ-45 on one end and MMJ on the other, and adding the resistors inside the body of a RJ-45 to DB9 converter.

Agreed on the memory -- my 3100 had I think 12 MB RAM originally, upgrading to 32 MB was a significant improvement. I think I paid about what that seller is asking for the *whole* system to get the two stacking RAM boards needed to get to 32 MB. I think my root disk is 131 MB, which is not very spacious, but since there's Ethernet on board, I can use network storage. I think I've got NFS up and going on there.
 
glitch said:
That's a really good price on DB25 MMJ converters. IIRC MMJ is some sort of balanced pair thing like RS-485, so you can convert to RS-232 with a few resistors. I've heard of people crimping a RJ-45 on one end and MMJ on the other, and adding the resistors inside the body of a RJ-45 to DB9 converter.
Click to expand...

This page is a good reference on all things MMJ:
https://www.lammertbies.nl/comm/cable/dec-mmj.html

The six available leads in the DECconnect MMJ connector are used for the main signals in serial communication: Tx and Rx for the data transmission and DSR and DTR for handshaking. In fact, the data and flow control signals are not true RS232 level signals, but RS423 level. The transmit and receive do not have a common ground, but they are differential, i.e. each line has it's relative ground level on a separate lead. By combining both floating minus leads and connecting them to the RS232 signal ground at the other side, signals can in practice be exchanged with a normal RS232 device. For this type of connection DEC sold a number of conversion adapters. For connection of two DTE devices (computers, printers, etc) the BC16E connection cable is available which automatically crosses the pins. Therefore the DEC MMJ system has a well defined way for null modem communication, something which is somewhat problematic with the original RS232 standard.
Click to expand...

If you pick up a DEC MMJ adapter such as an H8571-A or H8575-A DB25 adapter it should just work fine with standard RS-232 signaling. Then you just need to find a BC16E MMJ-MMJ cable, or equivalent.
 
gslick said:
If you pick up a DEC MMJ adapter such as an H8571-A or H8575-A DB25 adapter it should just work fine with standard RS-232 signaling.
Click to expand...

Yeah, thanks for making that clear, reading through my previous posts I apparently didn't :) Just to reinforce, you can in fact plug any of the DEC MMJ converter plugs onto a RS-232 port and it'll work. If you want to make your own converter from scratch, you'll need some resistors.

gslick said:
Then you just need to find a BC16E MMJ-MMJ cable, or equivalent.
Click to expand...

Yep, and I do have the stuff to make up cables, if anyone needs them. Paladin PA2067 is the die for DEC MMJ, if you've already got the Paladin 1300 or 8000 crimper frame. I think the MMJ ends I have are from Pacific Telecom.

The "automatic cross" for the BC16E cable is achieved by crimping the MMJ cable as "rollover" -- you put one of the MMJ connectors on upside-down, like with a Cisco console cable.
 
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