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SLU switch meaning

MattCarp

Experienced Member
Joined
Sep 5, 2003
Messages
279
Location
Atlanta, Georgia (USA)
PDP-11'ers... I just powered up my 11/73 after a very long time and it came up fine.

I have a question, does anyone know what the meaning is of the various switch positions?

The baud selector is clear, but I don't know what the icons mean on the other two and what the meaning is on the "9" on the alphanumeric display.

Internet search yields no results...

Ok, from the right, what is the meaning of the rocker switch's two positions? It doesn't seem to have an effect.

The middle selector. "T" with a circle around it - is that a loopback setting?

Any thoughts?

Thanks.
 

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PG31

Experienced Member
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May 31, 2011
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494
Location
Sefton, Meresyside, England
Odd, that CPU patch panel looks like the MicroVAX II panel and not an 11/73 from memory and also looking at MicroVAX II technical manual. I recall the 11/73 panel having a DB25 console port and a rotary switch that you use a screwdriver to set Baud rate with. I don't recall that panel in the photos being used on 11/73 but I'm getting old now:rolleyes: There are also two (possibly more?) different KDJ11 CPU boards and one has no built in console port.

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MattCarp

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Messages
279
Location
Atlanta, Georgia (USA)
Thank you for the diagram!

It's totally possible it's from a MicroVAX II. The machine was an eBay purchase almost 20 years ago, so it could have been a Frankenstein.


I am able to plug into the DB9 port for the console, so it's at least partially hooked up!

When I switch to loopback test mode, I see nothing on my terminal, which would be expected.

Now that I know what the rocker switch is, I'm not sure what that means, nor the language inquiry mode and hex display. But, this is a good start for me!


I suppose it's possible that someone put the PDP-11 into a BA23 that was used for a MicroVAX? They used that chassis for both lines, didn't they?

I do remember having to replace the system badge on the front near the power switch ("Micro PDP-11") but I don't remember what was there before, or why I needed to get that.
 

PG31

Experienced Member
Joined
May 31, 2011
Messages
494
Location
Sefton, Meresyside, England
Perhaps have a look at pages 38 onwards of the below manual. It is also worth checking if the battery is installed on the back of the console panel and checking it hasn't leaked.
I hope I'm not pointing you in the wrong direction, hopefully someone else can confirm if this same panel was used on PDP and MicroVAX and yes the BA23 enclosure that you have was used on both.

AZ-GLBAA-MN MicroVAX II 630QB Technical Manual.pdf (uni-stuttgart.de)
 
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bqt

Veteran Member
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Sep 15, 2019
Messages
506
Location
Zurich, CH
Nope. They did not use the same panel, and the selections on the uVAX panel do not even make sense on a PDP-11. You do not have different language options... I also have some doubt that the pinout of the cable between the cpu board and the panel is even compatible. And the uVAX have a battery in there for the TOY. The PDP-11 have no such thing, except the 11/93, and there the battery is on the CPU board itself.

I basically wouldn't even try using that panel on an 11/73...
 

MattCarp

Experienced Member
Joined
Sep 5, 2003
Messages
279
Location
Atlanta, Georgia (USA)
Thank you - it looks like the PDP-11 was assembled by someone in a uVAX BA23...

I think the pinout is compatible, since I'm able to get a terminal session working. I can experiment with the baud selector, but it is working at 9600-n-8-1
 
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