• Please review our updated Terms and Rules here

PDP-11/44 Restoration

That's a pretty awesome setup you have.

I'll probably buy one of those things soon. For the cable, where can I obtain one, and are the berg connectors easily obtainable? Also do I need the bulkhead connector that the manual mentions or can I just connect the cable from the cards directly to the tranceiver?
 
Last edited:
You can get everything you need to make cables from Jameco. As for the bulkhead plate, that's up to you how neatly you want to arrange everything.

The project documented in those pictures was my first learning about all things Unibus. I literaly started with pieces (often broken) making cables, wire-wrapping missing parts from the prints, and doing component level repairs (no board swapping!!). I even made my own switch register. I accumulated a lot of options and have since expanded the unibus even further. It's a little over the top for an 11/04, but it does all work. And best of all, I learned a hell of a lot. I am a strong believer in reading and studying manuals, so I was able to figure out most everything myself (because DEC manuals are awesome!).

I have half of and 11/34 processor and half of an 11/34a. I would gladly trade someone to get the other half. It would be nice to upgrade this machine to an 11/34 someday.

Lou
 
Thanks. I'll try to get all of those parts soon.

Your work on the 11/04 is very impressive. Thanks for sharing those photos. Good luck on getting the 11/34 built.

Once I am done fixing the PSU hopefully I won't have to work on the CPU any. The previous owner said that it worked the last time they turned it on, so I think that that is probably a good indicator that it will work.
The thing that I dread about installing the DEUNA cards is the possibility of having to change the jumpers on the backpane. The number of wires on the back is intimidating, especially since this is my first experience with a PDP computer.
 
Old Computers said:
Thanks. I'll try to get all of those parts soon.

Your work on the 11/04 is very impressive. Thanks for sharing those photos. Good luck on getting the 11/34 built.

Once I am done fixing the PSU hopefully I won't have to work on the CPU any. The previous owner said that it worked the last time they turned it on, so I think that that is probably a good indicator that it will work.
The thing that I dread about installing the DEUNA cards is the possibility of having to change the jumpers on the backpane. The number of wires on the back is intimidating, especially since this is my first experience with a PDP computer.
Click to expand...

Do you mean for the grant lines and such? What I did on my 11/84 was to see if I could find a slot that already had the wires
removed so I could just plug it in. Maybe some other board needed those removed and is no longer part of the system.
Best of luck. I have a DEUNA card too.
 
Yes, this cable will work. But for $50 (or even $10) I would build it myself.

As for the backplane jumpering, I am assuming you are talking about the CA1 to CB1 NPR grant chain. It is not that bad. Use a bit of tubing as a flag as you count the pins.

Lou


Old Computers said:
http://www.ebay.com/itm/DEC-70-2278...707?pt=LH_DefaultDomain_0&hash=item2eb492329b

Would this work for the bulkhead connection and the cable, or would there be a difference with cables since this is for DELQA?
Click to expand...
 
Lou - N2MIY said:
Yes, this cable will work. But for $50 (or even $10) I would build it myself.

As for the backplane jumpering, I am assuming you are talking about the CA1 to CB1 NPR grant chain. It is not that bad. Use a bit of tubing as a flag as you count the pins.

Lou
Click to expand...

You prefer to build everything yourself. :)
 
If it was just for the cable I would build it myself, but I am also looking at it for the bulkhead connector. As for building one, where could I find a wiring diagram? The manual doesn't appear to have one.

Those connections are the ones that I am worried about. Since it's wire-wrap I am afraid of breaking some other wires as well.

After reading the manual it appears that DEUNA allows remote booting. Does that mean I could set up a network drive with an OS image to boot from?
 
Is it a part of DECnet, or is it its own protocol, or is it a subset? (It's a little confusing.)

If it is a part of DECnet I believe that Ubuntu has a package to implement DECnet. The challange after that would be setting up the image to load off of that computer. I also assume that I could not use a router or hub with DECnet.
 
MP02379 for the DELQA has sheets detailing the cable and bulkhead assembly in the last few sheets.

As for the wire wrapping (or unwrapping), just take your time and be careful. In my experience, the CA1/CB1 jumpers have been at the top layer of wiring.

Lou


Old Computers said:
If it was just for the cable I would build it myself, but I am also looking at it for the bulkhead connector. As for building one, where could I find a wiring diagram? The manual doesn't appear to have one.

Those connections are the ones that I am worried about. Since it's wire-wrap I am afraid of breaking some other wires as well.
Click to expand...
 
Old Computers said:
Is it a part of DECnet, or is it its own protocol, or is it a subset? (It's a little confusing.)

If it is a part of DECnet I believe that Ubuntu has a package to implement DECnet. The challange after that would be setting up the image to load off of that computer. I also assume that I could not use a router or hub with DECnet.
Click to expand...

I'd be interested in finding out more about this too.
 
I found a pretty awesome tool for working with PDP-11s on the internet the other day. It is called PDP-11 GUI. This will probably come in handy for when I finally get the system running. When I get to the point of turning the computer on I probably will use my VT101 terminal, but I think that this program will be wonderful to test the memory because of the memory window.

The other cool thing about this program is that it comes with a version of Simh which the program can connect to.

Here is the program's webpage:
http://www.retrocmp.com/pdp-11/pdp11gui
 
Old Computers said:
I found a pretty awesome tool for working with PDP-11s on the internet the other day. It is called PDP-11 GUI. This will probably come in handy for when I finally get the system running. When I get to the point of turning the computer on I probably will use my VT101 terminal, but I think that this program will be wonderful to test the memory because of the memory window.

The other cool thing about this program is that it comes with a version of Simh which the program can connect to.

Here is the program's webpage:
http://www.retrocmp.com/pdp-11/pdp11gui
Click to expand...

I've tried it and was not fully impressed. I was hoping to find a different way to download
an image to a real disk on my 11/84. VTServer has worked in the past, but it's got a bug
if the file is over 32MB which some of the tar files are for BSD. pdp-11 GUI did not seem
to be able to talk to my RA92. So I am back to using the SCSI route, but don't have a
monitor for my Linux box right now. Most of my stuff got donated/given away when
I moved from Pa to NM. Let us know how the other features work. I did not try the
memory feature. I was not sure of the advantage of a "special" Simh for it's use.
I forget what it's for but it's limited.
 
I am still learning the PDP-11 and the software so I cannot comment too much on some of the features, but the memory feature displays a grid of memory locations starting and ending at a specified address. You can edit the values displayed in each box and then press deposit, and it changes the contents of the changed cells in the PDP. The terminal window is also nice, it shows all of the raw serial port activity going to and from the PDP-11.

I am not quite sure if the Simh is special, but I do think that it only has PDP-11s available for simulation. It is just to be able to use the software with if you don't own a real PDP or you need to learn the software.
 
I would like to get started on this project again. A quick summary of what is going on:

The PSU functions; that is it turns on and runs for a few minutes. After that it shuts down. Looking at the 5v DC out with my oscilliscope there is significant ripple, but that could be caused by intereference. I have made some better multimeter probes to use.

The pictures of the traces are around page 15 (I forget exactly). What should I do from here?
 
I have decided to explore one of the suggestions earlier in this thread. Tradde said that the power distribution box introduced some noise into his PDP-8 power supply. Would this be a good thing to check on my computer?
 
You must log in or register to reply here.
Back
Top