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DEC PDP-11 based Tektronox systems on Ebay.

MattisLind

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Just happened to see these two:

https://www.ebay.com/itm/254927982214

https://www.ebay.com/itm/265111563992

Tektronix 8501 and 8560 development systems.

Quite nice selfcontained PDP-11 based systems. Price is perhaps a bit high and I don't think there are just a few QBUS slots in them. There should be some kind of RT-11 variant to run on 8501, but I am not sure if the files on bitsavers are the RT-11 stuff. The 8560 runs TNIX. There seems to be dist files on bitsavers.
 

ftcnet

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enhance


I'm impressed with the thick (3mm?) PCB's that Tek used. I suppose they didn't want to deal with any intermittents due to board flexing. Could socketed IC's work their way out due to board vibration or flexing with thinner PCB's?
 

bladamson

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I apologize in advance for my ignorance, heh...

So I made an offer on that 8560.... From my reading it has the M8186 PDP-11/23 cpu board, which in theory ought to be able to run BSD, correct?

What else would I need to make it run OS'en other than TNIX (BSD in particular)? Would the QBone be sufficient?

Would it also be able to run RSTS and RT-11 in that configuration?
 

bqt

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I apologize in advance for my ignorance, heh...

So I made an offer on that 8560.... From my reading it has the M8186 PDP-11/23 cpu board, which in theory ought to be able to run BSD, correct?

What else would I need to make it run OS'en other than TNIX (BSD in particular)? Would the QBone be sufficient?

Would it also be able to run RSTS and RT-11 in that configuration?

An 11/23 won't be able to run any modern BSD. I don't know of maybe 2.9BSD might be possible, but anything beyond that most likely will not run, as the 11/23 have neither split I/D-space, nor supervisor mode.

However, both RSTS/E and RT-11 should run fine on that hardware. RSX-11M will also run fine. Assuming you have at least 512KB, -11M-PLUS will also run, but it will be a bit of a shoehorn, and my TCP/IP will not run on it.
 

bladamson

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An 11/23 won't be able to run any modern BSD. I don't know of maybe 2.9BSD might be possible, but anything beyond that most likely will not run, as the 11/23 have neither split I/D-space, nor supervisor mode.

However, both RSTS/E and RT-11 should run fine on that hardware. RSX-11M will also run fine. Assuming you have at least 512KB, -11M-PLUS will also run, but it will be a bit of a shoehorn, and my TCP/IP will not run on it.

Thank you, sir.

Yes, I was thinking 2.xxBSD. Or any sort of PDP-11 Unix. I think Unix v6 will run on it if it has the floating point chip, maybe......

Sorry again for my dumbness. I don't have any previous PDP-11 experience other than assembling a PiDP-11 and fiddling around with it. :)

The guy accepted the offer, so I guess I am committed now! I hope I didn't pay too much or get the wrong thing! It is certainly an attractive unit, though. It will be very happy with my 11401 sitting on top of it.

From the pictures, I think it has either 512k or 1mb of RAM (probably 512k), and an optional 6 port serial board. It definitely still has the 11/23 (non-plus) CPU board. There was apparently an 11/73 upgrade available, so my assumption is that I could drop a qbus 11/73 card into it without too much trouble, which might open up a few more doors vis-a-vis Unix versions and TCP/IP. I should probably get what I've got running properly before I start dumping money into it, though.........

Now to figure out how to get hold of a QBone board......
 

Al Kossow

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Just a warning that Tek used their own peripheral interface designs. You aren't going to be able to run
anything other than their V7 (Utek) on it. It also doesn't use QBus slots for anything other than the
DEC cpu board.

All of this is documented in the manuals for it on bitsavers
 

bladamson

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Just a warning that Tek used their own peripheral interface designs. You aren't going to be able to run
anything other than their V7 (Utek) on it. It also doesn't use QBus slots for anything other than the
DEC cpu board.

All of this is documented in the manuals for it on bitsavers

Yeah, I am a little worried about that... The manual says that their backplane is "like qbus, but with extra signals", so I am hoping that means that I can make a carrier for the qbone card and thereby get other OS'en running on it.
 

bqt

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Thank you, sir.

Yes, I was thinking 2.xxBSD. Or any sort of PDP-11 Unix. I think Unix v6 will run on it if it has the floating point chip, maybe......

Sorry again for my dumbness. I don't have any previous PDP-11 experience other than assembling a PiDP-11 and fiddling around with it. :)

The guy accepted the offer, so I guess I am committed now! I hope I didn't pay too much or get the wrong thing! It is certainly an attractive unit, though. It will be very happy with my 11401 sitting on top of it.

From the pictures, I think it has either 512k or 1mb of RAM (probably 512k), and an optional 6 port serial board. It definitely still has the 11/23 (non-plus) CPU board. There was apparently an 11/73 upgrade available, so my assumption is that I could drop a qbus 11/73 card into it without too much trouble, which might open up a few more doors vis-a-vis Unix versions and TCP/IP. I should probably get what I've got running properly before I start dumping money into it, though.........

Now to figure out how to get hold of a QBone board......

In general, if it has more than 256K, it's a 11/23+, since the non-plus could only address 256K.
Also, in this case, an upgrade to an 11/73 should be very simple. Basically replace the CPU card, and you're done.
With an 11/73, you would be able to run anything.

As for TCP/IP, you will definitely need something better than the 11/23. The only TCP/IP you can hope for on the 11/23 is the TCP/IP Baldwin wrote for RT-11.
 

TangentDelta

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I bought the 8501 and have been trying to understand it a bit better in hopes of porting RT-11 to it. It has been slow going so far due to the lack of technical documentation for this machine.

The only standard QBus slot in the system is where the LSI-11 CPU board lives. The rest of the slots are 100-contact connectors (similar to S-100) that carry QBus and I/O signals specific to the function of the slot. The auxiliary serial port lives at the standard address 177560 and when I halt the machine I get a normal ODT prompt. I have the bootloader ROM completely disassembled and have it about 75% of the way reverse-engineered.

The latest thing I've been working on has been understanding the floppy controller, which has a fault of some sort. It's Z80-based and directly accesses the LSI-11's bus to read and write system memory. The only register on the floppy controller that is addressable by the LSI-11 bus is a command pointer. The LSI-11 sets up a multi-word command anywhere in its memory space and stores the starting address of that command in the floppy controller's pointer register. The Z80 on the floppy controller is interrupted (via NMI) and reads from the command pointer register via the LSI-11 bus. The floppy controller's pointer register is on LSI-11 bus address 0o177160 (0xFE70 hex) but the Z80 accesses it at its own address at 0o160012 (0xE00A hex). I've been trying to figure out how the LSI-11 bus is actually mapped into the Z80's address space.
 
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