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View Full Version : VAX 11/750 on Craigslist in Pittsburgh



Lou - N2MIY
February 17th, 2009, 05:45 PM
Folks,

If you're near Pittsburgh PA, this could be fun:

http://pittsburgh.craigslist.org/sys/1031712303.html

It looks to be a VAX 11/750. The 11/780 was 1 VUP (VAX Unit of Performance), and this little brother was 0.6, but at least it may not need 3 phase 480V power.

Lou

pontus
February 17th, 2009, 11:00 PM
pretty neat machine. If I was closer I would definitely grab it.

tradde
February 18th, 2009, 04:42 AM
Vaxes never did much for me. Even at Penn State I didn't care for the new Vax replacing the older pdp-11/34. Just a big ugly box. Then again I prefer blinkenlights machines like the pdp-8, pdp-11/70, pdp-10 (KA-10). But for someone with an interest it sounds like a decent haul.
Tim R

NeXT
February 18th, 2009, 08:18 AM
pretty neat machine. If I was closer I would definitely grab it.

Same here. Yes it is no PDP but it's still something interesting so have in the house.

Lallander
February 18th, 2009, 08:42 AM
It turns out that it's a 11/23 not a 750. It's going to be a chore to pick it up, but assuming it is all still in good shape it looks like I've reached a deal with him. How does the 11/23 stack up to its brethren?

pontus
February 18th, 2009, 11:11 AM
heh.. an 11/23 is quite different from a vax indeed :) it is one of the more common PDP-11 and not very exceptional. I have one behind me that lacks the CPU-board.

Here is an introduction:

http://www.hampage.hu/pdp-11/1123.html

Crawford
February 18th, 2009, 01:45 PM
Sooo, except for not being an 11/750 of any ilk and in fact being an 11/23 ... the craigslist listing was entirely accurate ;)

I have had zero luck with the list'o'craig in actually buying something listed: inaccuracies, sellers being too snooty to answer questions, people wanting unreasonable amounts for things, not being at home when they say they will be, etc.

It's nice to look at, but not so useful for me so far...

Lou - N2MIY
February 18th, 2009, 04:05 PM
Having an 11/23 is better than not having an 11/23. I would not sneeze at it. It is easily upgraded to an 11/73 if the speed really is bothersome. This sounds like a very nice haul for someone 1.) single (so that they will not have a spouse to complain) 2.) within reasonable driving distance of Pittsburgh.

I have 11/73s and 11/23s (obtained prior to marriage.) The 11/73 feels about two times faster when it comes to doing routine things. However, the 11/23 is not bad at all. These are not toys, not home computers, not personal computers. They were serious machines for scientific and business computing.

With the RL02s, packs, terminals in the deal, this sounds like a great system to get started on. It's probably all mounted in a dec short rack too. There are plenty of us here who can help you get it going. So.... go get it!!!

Lou

Lallander
February 19th, 2009, 09:55 AM
What all does upgrading to a 73 entail, and can you upgrade the 23 or only the 23+?

pontus
February 19th, 2009, 11:13 AM
What all does upgrading to a 73 entail, and can you upgrade the 23 or only the 23+?

I think the 23+ is exactly the same as an 23, but with a different (quad height) cpu board. So you should be able to upgrade it to a 73

Lou - N2MIY
February 19th, 2009, 04:57 PM
So far I have collected and have these in running systems:

11/23 KDF11-A M8186, a dual height card that has no on board boot roms or serial ports (SLUs).

11/23+ KDF11-B M8189, a quad height card that has on board boot roms and SLUs.

11/73 KDJ11-A M8192, a dual height card with no on board boot roms and no SLUs.

11/73 KDJ11-B M8190, a quad height card with on board boot roms and one SLU. It also supports a special higher speed memory bus called PMI.

So, the usual 11/23 to 11/73 upgrade paths are M8186 to M8192 and M8189 to M8190. However, it is not difficult to take a different path, it will likely just involve another card or two (the bootstrap card like BDV11, or SLU card like DLV11-J, or a combo card that does both like MXV11-BF).

It should be mentioned that there were some revision differences on M8186s that made them specific to 18 or 22 bit backplanes (Q18 or Q22). I have these different flavors of M8186s.

Lou

Lallander
February 24th, 2009, 05:10 PM
All righty all, I'm going to go pick up this bad boy probably on Thursday. Is there anything I need to know about transporting it beforehand? I know that the RL02 drives should have the platters removed to keep from damaging them. Other than that however, is there anything else? Would it damage it to transport it on its side?

cosam
February 25th, 2009, 12:05 AM
You ought to lock the heads on RL02 drives if you can, although I've transported them unlocked before and never had any trouble. It's easiest if you have power to the drive so the lid opens with the release lever on top. Otherwise you can open the lid by unscrewing the four screws on the top/rear cover. In front of the heads is a small, square metal plate with a set screw in it. To lock the heads, you undo the screw a little, rotate the plate in front of the heads, then tighten the screw again. Of course: don't forget to unlock them when you get to turning it on!

If mounted in a rack, there may be a thumb screw at the back of one of the rails which should be done up to prevent the drive from sliding out the front of the rack. If not, you want to secure the drive(s) somehow as having them pop out at an unoppertune moment can topple the whole thing over.

If the CPU/backplane/PSU box is of the slide-out variety, make sure that's secured too or it could just slide right out of the rack. There are holes about half way down each side for shipping screws, but you'd need to find the right screws for them, of course.

I don't think transporting the thing on its side should be a problem, but if you're planning on hefting a short DEC rack into a truck, make sure you have a couple of reasonably strong helpers! If you can get a truck with a tailgate lift, it's definitely worth it. Check for loose bits and bobs in the rack first (especially in the bottom, in which I've found everything from ribbon cables to complete Qbus cards).

Above all, apply common sense and be careful hauling it around. These things are heavy!

pontus
February 25th, 2009, 06:29 AM
Jupp, make sure to secure the drive heads.

I picked up my 11/23 alone in a normal station wagon type car. The seller helped me get it into the trunk. It was heavy but manageable.

The head got stuck on one of the drives and I was unable to remove the disk before moving it. But when I got home I opened the RL01 service lid and was able to manually move the head back into position and remove the disk pack. I haven't tested the disc or the drive since I lack the processor card. The drive behaves normally though (loading and unloading packs).

(The RL01 and RL02 are very similar).

Here is one with the lid of:

http://www.youtube.com/watch?v=3PDOCw04E4Q

And here is the manual showing you how to secure the heads:

http://www.bitsavers.org/pdf/dec/disc/rl01_rl02/EK-RL122-TM-001_techAug82.pdf

chuckcmagee
February 25th, 2009, 06:42 AM
Ok, I am pretty much a total computer "NERD" as they say. I have heard "You guys are crazy! That stuff is SO boring." more times than I can count.

But......

Even I, the nerd, have to agree on this one. "Here's a disk drive being exercised by a diagnostic device. See the pretty heads go in and out real fast."

That video is very close to the top of that "you guys are crazy" :rolleyes:

Of course, Lorne and I are sitting there, with a flashlight, trying to watch floppy drive heads move. Results are in -- We are crazy :p

barythrin
February 25th, 2009, 08:03 AM
lol No useful help from me on the big systems since I've never been able to use them, so awesome on your find and good luck with the trip :-)

Only advice I have is the fairly obvious get a few sheets or old comforter so you don't scratch the system up. Plus it'll add some ease to sliding it onto and off of the truck or whatever you're carrying it in. If you are doing a truck be careful not to let it rest on just the tailgate too long (I know it's a nice pivot point for things that are really heavy) but get it past that quickly since a lot of tailgates aren't meant for a huge amount of weight (well I guess it's ok for two people but people have legs under them if the tailgate gives way).

Ditto on making sure things in the rack are secured. Nothing worse than tilting a rack forward just to find all the unscrewed components sliding out and falling to the ground.

Lallander
February 25th, 2009, 08:30 AM
It's all going in the passenger side of a two door chevy cobalt :eek:

I really hope everything goes well, but I got some measurements and it "should" fit. On the plus side it will be in nice and snug and won't have any room for bits to fall out.

Edit: I removed the passenger seat if anyone was wondering.

ddsnyder
February 27th, 2009, 05:45 PM
I have seen the machine as I thought of buying it last year, but
I lack space for a 11/23 machine. The seller lives near Pittsburgh,
been to his home and looked over his collection. He originally
advertised it as a Vaxstation 3500, I wanted one, but when I saw
what he had, I declined.

pontus
March 11th, 2009, 06:05 AM
Lallander: Have you picked the beast up yet? Would be fun to hear what you got!

Lallander
March 11th, 2009, 07:47 AM
Sure thing, I got it back a week ago. I got the main PDP-11/23 in a rack with two RL02 drives and 5 platters. I also got a VT220 + keyboard and a Vaxstation 3300. It also had some spare boards for the PDP and the field service manual.

I haven't tried booting it up for several reasons. I'm missing some power cables, during the move we tried to take it apart incorrectly so I have to put the rails for one of the RL02s back together, and I haven't had time to check it over for corrosion or other damage yet.

The main unit looks remarkably like this but is in slightly worse shape (rust etc) http://www.joefmiller.net/Bilder/Computermuseum/PDP11-23G.jpg

pontus
March 11th, 2009, 07:52 AM
Sure thing, I got it back a week ago. I got the main PDP-11/23 in a rack with two RL02 drives and 5 platters. I also got a VT220 + keyboard and a Vaxstation 3300. It also had some spare boards for the PDP and the field service manual.

I haven't tried booting it up for several reasons. I'm missing some power cables, during the move we tried to take it apart incorrectly so I have to put the rails for one of the RL02s back together, and I haven't had time to check it over for corrosion or other damage yet.

The main unit looks remarkably like this but is in slightly worse shape (rust etc) http://www.joefmiller.net/Bilder/Computermuseum/PDP11-23G.jpg

Cool, looks just like mine. In a few weeks I think I'll start working with my 11/23.. unless I start with the VAX.. or those other computers waiting for fixup :)

What boards did you get?

Lallander
March 11th, 2009, 08:10 AM
No clue. What I posted in the previous post pretty much sums up all of my knowledge of the 11/23 :)

When I have the time and can find my camera I'll start taking some pictures and get a help me get this kajigger working again thread started perhaps.

cosam
March 11th, 2009, 08:13 AM
Sure thing, I got it back a week ago. I got the main PDP-11/23 in a rack with two RL02 drives and 5 platters. I also got a VT220 + keyboard and a Vaxstation 3300. It also had some spare boards for the PDP and the field service manual.
...
The main unit looks remarkably like this but is in slightly worse shape (rust etc) http://www.joefmiller.net/Bilder/Computermuseum/PDP11-23G.jpg
Cool - sounds and looks similar to a system I picked up about a year ago, although mine was originally a 11-23+ and had been upgraded with a 11-73 CPU. Even so, you might find some of my notes (http://www.cosam.org/computers/dec/pdp11-23/) useful. I don't know off hand if the "regular" 23 has a different backplane though, so be careful. It'd be interesting to hear which cards you got with the machine.

For documentation, have a look at http://vt100.net/manx/ which also indexes the bitsavers.org (http://www.bitsavers.org/) archive.


I haven't tried booting it up for several reasons. I'm missing some power cables, during the move we tried to take it apart incorrectly so I have to put the rails for one of the RL02s back together, and I haven't had time to check it over for corrosion or other damage yet.
You can always pull the system box out of the rack and run that off a regular power cable. If your PSU is like mine, it will require no load to run, so you can pull all the cards and check the voltages are reasonable. From then on it's a matter of building up your system one step at a time. Great fun ;-)

Two tips spring to mind: Firstly, checking the jumpers on all cards before use can save you a lot of grief. Second, before using old RL02 disk packs, shine a bright light in there and check they're clean; if in doubt, don't use it.

Lou - N2MIY
March 11th, 2009, 05:01 PM
The regular 11/23 has an H9273 Q18 (18 bit) backplane. So, it can only support 128kW of ram. It usually had an M8186 processor.

An 11/23+ has a Q22 (22 bit) backplane and so can support the full 2MW of ram. It would have an M8189 processor.

Lallander, the most helpful thing would be to raise the back cover on the enclosure in the rack where the backplane is (the unit that has the three switches on the front) and to jot down and post the card numbers that are on the handles of the boards. They will all start with M. A photo where we can read the numbers off the handles would be just as good.

Lou

Lallander
March 11th, 2009, 06:02 PM
Cool beans, I'll do that when I get the time to actually invest in the machine. New quarter of college is just starting up and it is a humdinger. So it will be a good while before I get into it.