UniBone: Linux-to-DEC-UNIBUS-bridge, year #1

[Joerg Hoppe]

Its been a long time since last public post about UniBone, time for a bragging broadcast.

What it is:
In case you forgot: UniBone is a plugin board to DEC PDP-11 UNIBUS systems containing a BeagleBone Black.

See http://retrocmp.com/projects/unibone.

This combo can simulate PDP-11 devices embedded in a physical machine.
So you can operate and repair incomplete UNIBUS PDP-11s and even VAXes, just be emulating the missing parts.
Disk drive emulators accept SimH image files, which can be ftp'd to the emualtior (no SDcard cahnging!).

As UniBone can acquire bus mastership, its also UNIBUS diagnostic console, as well as stimulate individual UNIBUS lines.

Realtime stuff is implemented on BBB's PRU coprocessors.
All programming is done in plain C/C++ under mainstream Debain Linux.


Whats new in 2019:
UniBone started with memory and RL11/RL02 emulation.
In 2019 we did a lot of programming and debugging (suppressing endless techno-babble here).

Thanks to some gifted supporters, we have now these devices:
- DL11 serial port (first concept by David Richards)
- 11/20 CPU (Angelo Papenhoff)
- RK06 and MSCP disk drives (Josh Dersch)

In fact UniBone implements now a complete PDP-11 system... a bit like a SimH with UNIBUS interface.

UniBone was tested (at least) against PDP-11/05, '34, '44, '84 and VAX 11/750.
Verified OSses include XXDP, Unix V6, 2.11BSD, RT11, RSX11M/M+, VAX 4.3BSD and Ultrixes.
Special thanks to Mark Matlock for endless testing.

Available?
Soon. About 25 complete systems were distributed, and the same amount in kits. Not much complaints.
User group at https://groups.google.com/forum/#!forum/unibone
Just now I'm planing for a 2nd lot.
And it will be shown on http://vcfe.ch/doku.php in Zurich on Nov 30th/Dec 1st, probably plugged into a PDP-11/05.

best regards,
Joerg

 

[Roland Huisman]

Very nice! Maybe I get an Unibus system in the near future.
So this would be a great addition. What are the costs for this board?
And is it possible to get PCB files when you are out of stock?

Regards, Roland

 

[Joerg Hoppe]

Very nice! Maybe I get an Unibus system in the near future.
So this would be a great addition. What are the costs for this board?
And is it possible to get PCB files when you are out of stock?

Regards, Roland

Hi,
See
http://www.retrocmp.com/projects/unibone/283-unibone-getting-one
for conditions.

I'm just ordered prototypes for the next board generation.
When everything is OK, I'll publish the KiCad project also on
https://github.com/j-hoppe/UniBone

The intend behind my "broadcast" was also to probe public interest, I'll make enough PCBs then for 2-3 years.

regards,
Joerg

 

[daver2]

Hi Joerg,

Nice job.

I have an 11/45 I am resurrecting. It has the CPU and FPU but no memory cards or I/O devices. I do have some spare SPC slots in the UNIBUS backplane, so this looks like the way for me to go!

Count me in for a unit - and it will hopefully spur me into action...

Incidentally, I sent you an e-mail a while ago via retrocmp.com regarding some of the flip-chips you have for sale (R, S and W types). Did you receive it or would you like me to resend or send it via a PM from VCFED?

Dave

 

[fritzm]

Hi Joerg,
I have an 11/45 I am resurrecting. It has the CPU and FPU but no memory cards or I/O devices. I do have some spare SPC slots in the UNIBUS backplane, so this looks like the way for me to go!

A quick note for Dave re those 11/45 CPU backplane SPC slots: you will want to verify that your backplane has wiring to distribute +15 to those slots. Early 11/45s (like mine) did not; it was added later as an ECO. It’s easy enough to wrap it on yourself if it is missing. Without this, many SPC interfaces won’t work correctly in those slots.

 

[Joerg Hoppe]

A quick note for Dave re those 11/45 CPU backplane SPC slots: you will want to verify that your backplane has wiring to distribute +15 to those slots. Early 11/45s (like mine) did not; it was added later as an ECO. It’s easy enough to wrap it on yourself if it is missing. Without this, many SPC interfaces won’t work correctly in those slots.

UniBone is powered on +5V only, so the emulated devices run even in case of errors in other voltages.
Joerg

 

[fritzm]

UniBone is powered on +5V only, so the emulated devices run even in case of errors in other voltages.
Joerg

Nice. I could get a lot of use out of one of these, too, and would also be interested in a board or kit once you are re-stocked.

 

[daver2]

Thanks for the info guys.

Dave

 

[bqt]

A quick note for Dave re those 11/45 CPU backplane SPC slots: you will want to verify that your backplane has wiring to distribute +15 to those slots. Early 11/45s (like mine) did not; it was added later as an ECO. It’s easy enough to wrap it on yourself if it is missing. Without this, many SPC interfaces won’t work correctly in those slots.

There are two different kind of SPC slots. Normal Unibus Device, and Modified Unibus Device (also called MUD). Look at any PDP-11 documentation, and you'll find out which slots are MUD.
An 11/45 is so old that MUD had probably not been invented yet. Nice that they did an ECO for it.
Note that the slots where the Unibus comes in or goes out of a backplane is never a MUD.

 

[Joerg Hoppe]

A quick note for Dave re those 11/45 CPU backplane SPC slots: you will want to verify that your backplane has wiring to distribute +15 to those slots. Early 11/45s (like mine) did not; it was added later as an ECO. It’s easy enough to wrap it on yourself if it is missing. Without this, many SPC interfaces won’t work correctly in those slots.

That reminds me:
While missing voltages are not a problem for UniBone, early SPC slots have another shortcoming:
On an 11/40 in Berln (http://retrobyte.de/dec-pdp-11-40.html) we found
that NPG was not routed through the SPC slots (CA1-CB1), only BG4,5,6,7.

Perhaps in early times DEC distinguished between "BIG" peripherals (DMA capable multi card disk/tape controllers)
and "SMALL peripheral controllers" without DMA.

Joerg

 

[daver2]

Just checked my 11/45 backplane and (you are 100% correct) the SPC slots only have the BG/BR wired and not the NPR/NPG.

Thanks for the 'heads-up' Joerg.

A little bit of wire wrapping therefore required...

Dave

 

[Joerg Hoppe]

Just checked my 11/45 backplane and (you are 100% correct) the SPC slots only have the BG/BR wired and not the NPR/NPG.

Thanks for the 'heads-up' Joerg.

A little bit of wire wrapping therefore required...

Dave

Volker in Berlin goes a "wrap-less" route: he breaks NPG from the end terminator back to UniBones NPGIN and from NPGOUT forward to the terminator again.
He uses an "UniProbe", but this will work with M930 also.
http://www.retrocmp.com/tools/uniprobe

Joerg

 

[fritzm]

Just checked my 11/45 backplane and (you are 100% correct) the SPC slots only have the BG/BR wired and not the NPR/NPG.

Out of curiosity, Dave -- what's the serial number on your 11/45 backplane/system?

Noel and I found while working through a Unix V6 boot issue on my machine last year that there are discrepancies with very early '45s and their memory parity handling as well. This turned out to be unrelated to my boot issue, but was uncovered during investigations along the way... It does impact the ability to run certain memory diagnostics.

So far I have not found a set of schematics that 100% accurately reflect the revisions of various CPU boards that are in my machine, nor have I managed to find the detailed ECO contents necessary to get there by "subtraction". Things are close enough that I was still able to debug and repair my machine, though. Probably a good topic for a different thread when you get further in to your restoration!

--FritzM.

 

[daver2]

I'll have a look. It will have to be next weekend now (I will be on a business trip shortly)...

Fortunately, I have the complete documentation pack that came from DEC for my machine .

Dave

 

[elb]

I am interested in a UniBone, I've been putting off sending in an order for a while. I'll get one in so my interest can be counted. I hope to make a hardware PDP with emulated drives available for student tinkering (since the drives are what is most likely to dislike running for days or weeks at a time after 30+ years).

 

[bqt]

Just checked my 11/45 backplane and (you are 100% correct) the SPC slots only have the BG/BR wired and not the NPR/NPG.

Thanks for the 'heads-up' Joerg.

A little bit of wire wrapping therefore required...

Dave

So that would mean that the NPG is wired directly from the Unibus in to the Unibus out slot then? I've never seen a backplane like that. And I thought I had seen most everything.

 

[gnupublic]

Volker in Berlin goes a "wrap-less" route: he breaks NPG from the end terminator back to UniBones NPGIN and from NPGOUT forward to the terminator again.
He uses an "UniProbe", but this will work with M930 also.
http://www.retrocmp.com/tools/uniprobe

Joerg

Yes



It's like shown in the picture. If the Unibone is not connrcted with a cable I use a simple jumper. Maybe you have to cut a trace if you use a M930.

Best regards
Volker