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BB08, Ebay find, hm....

C

czunit

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Well, I bought an old pdp8 item from Ebay. Mainly got it for the wire wrap sockets and power supply (want to build a memory expander for my 8/L) but now that I have it I should figure out what it is.image4.jpeg

Very odd, consists of 8 flip chips and what is the programmed IO lines from a pdp8. Now that I have it, I see that the flex cables coming in are double sided to single sided, so it probably went in a pdp8/I. Which means it could be posibus or negibus....

However removing the modules showed a DEC factory plate.
image1.jpeg

What is a BB08N? Didn't see anything in the 1970 Small Computer Handbook about it, maybe it is their nomenclature for a generic module just as a BA08 is a generic box?

The real interesting part is how clean it is. Not only has this probably never been used I think it was stored in a helium filled container as there is no rust, corrosion, or ANYTHING on this unit.
image0.jpeg

And oddly enough, the power supply is not only in perfect condition (not a spec of dust in there) but it also has a schematic on the side. If anyone wants, I can post it, but it's for a H716.

Any idea what it might have been? This seems too nice for me to just take apart and rewire....
 
More data: Looks like it was made in Feb 1973. Pretty late all things considered, I'm not sure if anyone was using Negibus at that time. So it might "work" on my 8/L.

IMG_1595.JPG

Someone really wanted us to know it was a BB08, maybe this was a DEC job?

IMG_1596.JPG

And finally, a picture of the schematic for the power supply.
IMG_1594.JPG
 
Looks like a great candidate for some backplane tracing! I have never heard of it before, but the N on the end probably suggests Negibus. I'd say 8/I folks were certainly still using their Negibus systems when this was built.
 
BB08N does suggest Negibus, as do the M102 device decoders, M100 Negative bus receivers, and M663 Negative Bus drivers. There are Posibus equivalents (M103, M101, M661) if you wanted to convert it for use on your 8/L.

The rest of that are just gates and latches. I can't but wonder if something was meant to plug in in addition to the 8/I cables. Are there any empty-but-wired slots?

Interestingly, the presence of two M102 seems overkill (two 6xx device codes) for what seems a very simple device.

I can still look aroud for a spare bit of backplane, if you like.
 
Yep, the M633 is a negibus driver card, and the M102's are device selectors for Negibus. So what would you do with a 216, 113, 111, and a 100......
 
I'm thinking parallel port...one device code for input, another for output, state flags, some gating.

Problem is, the "input" side doesn't seem to have enough drivers to drive a data value onto the bus. (Two, tops, assuming seperate drivers for IRQ and SKIP for each device.)
 
A little info found in Option Module Listings:

BB08-N bus interface with 24 unwired slots 8 Neg
BB08-P bus interface with 24 unwired slots 8 Pos

I'll look later to see if I have anything in my old microfiche stash.

Dale
 
vrs42 said:
Here we go. It's described in:
starting on page 294 of the PDF (Posibus version).
Click to expand...
Yep, that looks like it. It's basically a pdp8 version of a VaxBI BIIC :-)

Looking at the wiring I can see that there are user installed wires going over to slot 9 and that's it, so it was probably a custom interface to a pdp8/L with basic parallel input and output.

Need to think about what I'd want to hook up, what I'd really like is to build my own Omnibus adapter (so I can use the memory controller and core memory from this dopey 8/E on the 8/L) or as I mentioned a interface to connect up vrs' really neat MM8/I interface board set.

At the same time, if I can switch a negibus device to posibus simply by replacing the bus drivers then maybe I could build a pair of boards for this AF01 A/D converter and do something with that.....
 
I do have the machine readable CAD files for the BM8L online. That's the gizmo that adapts an 8/L for Omnibus memory. It's a 4x20 backplane. About half the slots are wired accross in a couple of simple patterns, though.

I suspect the messy bits could be reduced to a couple of CPLD. (Probably at least two because of the high pin count, rather than the complexity of the logic.)
 
I am interested in all kinds of expansion of the PDP-8/L and the BA08. I don't know what is compatible with the 4 port Multiple Controller
(DC02-A) and Data Station (DC02-D) on the BA08.

My plans are for now, to add the power fail and Data Break capability to the PDP-8/L itself, if I can find the boards. And then add the Real Time Clock (KW8/LF) and Oscilloscope Display and Control (VC8/LA) to my BA08 (Once I get it working).

I would love to have a way to get more than 8K in the 8/L without adding any more large BA08 size boxes.

Here is what I hope to do with the system:

  1. Get the PDP-8/L fully functional.
  2. Convert the Teletype interface to RS-232.
  3. Add a high speed serial port for serial disk or modify the current I/O board for high speed and Console Disk.
  4. Add the power fail option (based on availability of an M703 board)
  5. Rebuild the power supply for the BA08
  6. Get the 4K expansion memory in the BA08 up and running
  7. Add the real time clock (KW8/LF) to the BA08 (needs one M405, three M903 and two M906).
  8. Add the oscilloscope display and control to the BA08 (needs A607, M701 and W020).
  9. Add an omnibus interface (that way I can add memory, serial ports, boot loader and disk interfaces).
  10. I #9 isn't possible then find some way to expand the memory to at least 16K and preferably 32K.
Any suggestions and help would be greatly appreciated.

I will have the 8/L and BA08 at the VCF Midwest show.
 
Bitwiz: Hm. You're a step ahead of me with the expansion box but once you get the 8 running you will of course want moar.

@vrs has an amazing pair of boards that replace the old serial baud generator and interface card with a top-notch RS232 that can go to 38400 baud. Highly recommended.

Likewise he's been working on a mm8/i replacement for the pdp8/I and I think with a bit of encouragement would be able to build a memory system that would just plug right into the 8/L itself. Maybe with an RX02 interface and adapter too.

Then after that.... Well you'll start wondering if you can hook an FPP-12 up to the 8/L.......
 
BitWiz said:
I am interested in all kinds of expansion of the PDP-8/L and the BA08. I don't know what is compatible with the 4 port Multiple Controller
(DC02-A) and Data Station (DC02-D) on the BA08.

My plans are for now, to add the power fail and Data Break capability to the PDP-8/L itself, if I can find the boards. And then add the Real Time Clock (KW8/LF) and Oscilloscope Display and Control (VC8/LA) to my BA08 (Once I get it working).

I would love to have a way to get more than 8K in the 8/L without adding any more large BA08 size boxes.

Here is what I hope to do with the system:

  1. Get the PDP-8/L fully functional.
  2. Convert the Teletype interface to RS-232.
  3. Add a high speed serial port for serial disk or modify the current I/O board for high speed and Console Disk.
  4. Add the power fail option (based on availability of an M703 board)
  5. Rebuild the power supply for the BA08
  6. Get the 4K expansion memory in the BA08 up and running
  7. Add the real time clock (KW8/LF) to the BA08 (needs one M405, three M903 and two M906).
  8. Add the oscilloscope display and control to the BA08 (needs A607, M701 and W020).
  9. Add an omnibus interface (that way I can add memory, serial ports, boot loader and disk interfaces).
  10. I #9 isn't possible then find some way to expand the memory to at least 16K and preferably 32K.
Any suggestions and help would be greatly appreciated.

I will have the 8/L and BA08 at the VCF Midwest show.
Click to expand...
Hi BitWiz,
I made an FPGA expansion card for my PDP-8/L. https://hackaday.io/project/202048-pdp-8l-enhancements
It plugs in the back 3 slots of the PDP-8/L giving it dectape, decpack, 32KW memory etc and it seems to work.
For example, it'll boot OS/8 and run the music program and run the maindecs.
I'm planning on bringing it to VCF East show next month.
Anyway you mentioned DC02 and I was wondering if you have any doc on that, because I want to get Edusystem 20 Basic running with multiple terminals.
Thanks,
Mike
 
Mike Rieker said:
Hi BitWiz,
I made an FPGA expansion card for my PDP-8/L. https://hackaday.io/project/202048-pdp-8l-enhancements
It plugs in the back 3 slots of the PDP-8/L giving it dectape, decpack, 32KW memory etc and it seems to work.
For example, it'll boot OS/8 and run the music program and run the maindecs.
I'm planning on bringing it to VCF East show next month.
Anyway you mentioned DC02 and I was wondering if you have any doc on that, because I want to get Edusystem 20 Basic running with multiple terminals.
Thanks,
Mike
Click to expand...
Ok that is what's needed here. Got a pcb and parts list?
 
github.com

GitHub - mrieker/pdp8l: PDP-8/L project files

PDP-8/L project files. Contribute to mrieker/pdp8l development by creating an account on GitHub.
github.com github.com
There are 4 boards in the zturn directory (zturn36, zturn35, zturn34b, zturn34d) and the front panel board that piggy-backs on the backplane is in pipan8l/pcb3.
I have sent a new design for the piggy-back board out for manufacture that is just a thin strip that only covers row 1 instead of like 8 rows of backplane pins.
I do have a few extra board sets...
 
I'm going to bring them to VCFEast but if you aren't going to be there, I could sell you a set online. Send me your email in private message.
 
Mike, for those that won't be at VCF E to ask you in person, can you describe your design methodology and any features/limitations with your unit?
 
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