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Repair Story - PC11/PC05 Papertape Reader Punch

L

Lou - N2MIY

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Albuquerque NM / Potomac MD
For those of you who like vintage hardware repair work....

For the hour here and there I've had over the last few weeks I've repaired and tested a PC11/PC05 that Will had in his attic for many years.

This PC05 and its PC11 controller were made in 1981 from all the date codes. I am amazed that it was still in production then. This is a very new PC05! http://www.vintage-computer.com/vcforum/album.php?albumid=232&attachmentid=18805

After a thorough cleaning, it had a few problems that needed repair. Most of the problems were related to the punch: http://www.vintage-computer.com/vcforum/album.php?albumid=232&attachmentid=18800

First I noted that one channel had no punches. The problem was a bad 2N3009A on one of the punch driver boards. The problem was located quickly by swapping boards and watching the bad punch follow. There are three M044 driver boards. Two each drive four channels, while the third board has two drivers paralelleled to drive the index hole punch, which never gets a rest. http://www.vintage-computer.com/vcforum/album.php?albumid=232&attachmentid=18804 I ended up replacing the bad transistor with one that was ten years older than the bad one.

Then with all punches firing, the next step was to try to run the ZPCAE0 diagnostic. I could run the punch routine to make a test tape, but it wouldn't read right. Not at all at first. I had to adjust the lamp brightness by the big resistor that mounts to the front panel that can almost be seen at the bottom center of this picture: http://www.vintage-computer.com/vcforum/album.php?albumid=232&attachmentid=18801 . I also had to adjust the threshold pot on the G918 phototransistor amplifier.

With the reader now reading, it was telling me there were errors on the test tape. I found that the punch mechanism needed oiling since some interposers would occasionally stick. My first inclination was to look for an electrical failure, but I found that all the punch solenoids were being driven correctly. The problem truly was sticky interposers. The problem was triggered interposers dragging adjacent untriggered ones along. Can you tell the channel with the sticky interposer? :http://www.vintage-computer.com/vcforum/album.php?albumid=232&attachmentid=18803 . And it wasn't always the same channel getting stuck. However, a good oiling with light machine oil got everything loosened up nicely. The punch mechanism is quite nice. It reminds me of an electric typewriter (we had a Sperry-Rand electric at home.)

So, with that all done, a cleanly punched tape with ZPCAE0 routine 3 now reads without error under routine 4. It all works quite nicely now http://www.vintage-computer.com/vcforum/album.php?albumid=232&attachmentid=18799 and my lowly 11/04 now has yet another mass storage device. The PC11/PC05 is particulaly nice to me to have since it is supported by CAPS-11.

I found that XXDPV2.5 no longer had ZPCAE0, but it was on the V2.2 RL distribution. I made a V2.2 RL02 pack image and used Reinhard's emulator to run XXDP from during all this work. This was also a good test of Reinhard's emulator back on an RL11 since all my final debugging was done on the RL8A (pdp-8/a). (Yes, I know I still need to make final drawings of that project, but actually restoring hardware is more fun!!!)

Lou
 
Well, I'm happy for you and also jealous that I don't have a high-speed reader and/or punch yet. Cool stuff!
 
Very nice!

It is something special about papertapes. The individual bits are so visible compared to most other storage mediums. Then the sound from the punch...

I have five PC04. One is a reader only. But no PC05 unfortunately. Two of them are older ones from a pdp-8/L system and the others from pdp-8/e systems. They are all manufactured in the early seventies so they have the dreaded Sprague Clorinol PCB filled run capacitor which I have to replace.

I'd love to have a PC05 with my 11/04. I have even been contemplating rebuilding an PC04 into an PC05. I guess that the boards needed are sitting in the pdp-8/L somewhere and could be borrowed from there. Maybe someone want to trade a PC05 for a PC04?

Anyway, some time ago I interfaced a PC04 reader with a PC (MAC) using an Arduino board. I made a short description of it here and also a video.
 
Sorting out paper tape punches can be fun and frustrating. I had my DSI2400 drive me nuts when I first got it. The chads kept jamming. Tried everything I could think of to figure out why. Eventually I realized that in shipping, the assembly for the entire punch unit got jammed at a slight angle and didn't vibrate freely. Apparently DSI used the vibration of the unit (mounted on rubber engine type mounts) to shake the chads into ejecting from the punch head. All I did was lift the entire punch assembly up so it moved and vibrated freely and I was in business.

My Facit 4070 unit was another story to get running, but it's just a spare right now.

Once you have the fun of paper tape, it's kinda hard not to get really into it. Once I got a computer controller high speed reader it was so much cooler than using a disk drive. I could see the program load. LOL

Cheers,
Corey
 
Mattis,

Indeed it is very nice to see the bits directly by eye. I have thought about punching some ASCII text and asking the children to "decode the message" by hand. That would give them a very good appreciation for data storage.

I studied the prints, and you could convert a PC04 to a PC05, but you would have some substantial backplane rewiring to do also. I looked to see how hard it would be to make up something that could be used on the 11 or 8, but decided that was too much.


Corey,

I have an DSI LRP300 (slower little brother) of your DSI2400, which I intend to use as a low-speed reader punch on my 8/e. I have cleaned it up, but not run it yet, as I can't seem to find a manual for it and would like to read that first.

Lou
 
Does your unit have the same color scheme as my dsi2400. It's the dec color scheme and matches a PDP nicely.

I had a lot of trouble finding my manual also in pdf and it didn't match the decal on the inside for "options". It was strait forward enough reading the sticker inside that told me what dip switches to set. I couldn't find a schematic though. If I need to fix something. I'll have to trace blindly.

Good luck,
Cheers,
Corey
 
Al Kossow said:
Could you add the PDP-9 paper tape images that you read to you web page?
Click to expand...
The ten latest images I did for RICM are already there. I recognized though that the first five I imaged was just sent through mail and never made its way to the webpage. This is now fixed. I have a few more, but those RICM already had so I haven't made images for those. Lou, sorry for hi-jacking your thread.
 
MattisLind said:
I'd love to have a PC05 with my 11/04. I have even been contemplating rebuilding an PC04 into an PC05. I guess that the boards needed are sitting in the pdp-8/L somewhere and could be borrowed from there. Maybe someone want to trade a PC05 for a PC04?
Click to expand...

What are the differences between PC05 and PC04?

And what is the name of the reader/punch attached to your PDP-9? It looks a lot like the reader/punch that Update has on it's PDP-8/I
 
pontus said:
What are the differences between PC05 and PC04?
Click to expand...

It's pretty clear from the module utilization in the print set. PC04 has no on-board intelligence whatsoever. PC05 however has the M715 reader clock, M7050 reader control, and M710 punch control.

I believe that the PC04 cannot advance the tape through the reader or punch without the controller in the computer being operational. The PC05 can without.

Lou
 
Lou - N2MIY said:
It's pretty clear from the module utilization in the print set. PC04 has no on-board intelligence whatsoever. PC05 however has the M715 reader clock, M7050 reader control, and M710 punch control.

I believe that the PC04 cannot advance the tape through the reader or punch without the controller in the computer being operational. The PC05 can without.
Click to expand...
That sounds about right to me.
 
Here is what the DEC manual for PC04/05 says about them:

Capture.jpg

So PC-04 for PDP-8I/L/E series with a more complex controller in the CPU box. PC-05 for PDP-11/12/15 with a simpler controller in the CPU box.

I suspect one could come up with a PC-04 controller for a PDP-11, and a PDP-8e controller for a PC-05, but they would be custom designs.
 
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Interestingly, what DEC did was to simply move the logic they had in the 8/L (and maybe others) into the PC05. The 8/L has a M705 (not M7050 but I suspect that they are very similar), M710 and M715.

Screen Shot 2014-05-28 at 9.06.10 AM.jpg.
 
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So physically the PC04 and PC05 are the same, perhaps with exeption the wiring of the small backplane inside the PC0X ?

Mattis, what is the reader/punch in the PDP-9 called? it looks very different.
 
pontus said:
So physically the PC04 and PC05 are the same, perhaps with exeption the wiring of the small backplane inside the PC0X ?

Mattis, what is the reader/punch in the PDP-9 called? it looks very different.
Click to expand...
Yes. PC04 and PC05 is the same except for the backplane. But exterior wise they seem to have changed over time. The ones for PDP8/L doesn't have the same buttons as the ones for PDP8/E, although they appear to be PC04 all of them.

The PDP-9 schematic calls it PC01 but I haven't checked the actual hardware. But it resembles the PC04 a lot except for the buttons and some small hardware differences.
 
MattisLind said:
Yes. PC04 and PC05 is the same except for the backplane. But exterior wise they seem to have changed over time. The ones for PDP8/L doesn't have the same buttons as the ones for PDP8/E, although they appear to be PC04 all of them.

The PDP-9 schematic calls it PC01 but I haven't checked the actual hardware. But it resembles the PC04 a lot except for the buttons and some small hardware differences.
Click to expand...

The 8i I had years back had a PC01 attached. It did look quite like a PC04.
 
The idea of having a a paper tape reader with my system kept haunting me. As some of you indicated it is quite a major difference between the backplane of a PC05 and a PC04. Reconstructing the PC05 although that the I have the cards for it leaves me at a position where I still lack the M7810 unibus board.

But, DEC made AFAIK the API towards the low-speed reader (TTY) and the high speed reader quite similar. Wouldn't it be possible to use a DL11 board together with an extended version of my Arduino-based PC04 controller? I think that the reader enable is there as bit 0 in the status register.
The error bit is missing though, but that might not be a big problem. The modification to the DL11 would then be to switch to a 1920 kHz crystal and set the baud rate to 3000 bps / 500 bps to work with the rate of the reader and punch.

Now since that I already have the reader code in place I guess that I need to make the punch code in the AVR chip.

What do you think? Is this a good idea or am I missing something?

BTW. Is it really punching at 50 CPS in Sweden? This is 50Hz land. Not 60Hz.

EDIT. I checked the manual more carefully this time: There are in fact two different pulleys; one with 18 groves and one with 20 groves.
 
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This does indeed seem like a good idea. Back in the day, if you had an ASR33 on your system, that was considered a low speed reader/punch. I think you could easily make one of your PC04s work like an RS232 connected low speed reader/punch. It would share the console TTY DL11, because that's how the ASR33 was connected. The PC: bootstrap rom for the M9312 supports both the PC11 high-speed reader punch and the low speed reader punch.

There are probably more people than just you who have the PC04/05 but not the bus interface card. I think there would be a few people interested in building copies of your work.

I have a different but similar papertape reader project to work on. I recently also got a reader from an old CNC milling machine. I need to build exactly this device http://juliepalooza.8m.com/sl/remex.htm that Steve Loboyko built. I have exactly this reader. This is similar in scope to the reader half of your project.

Lou
 
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Hi All;
Lou, I have a Remex Paper Tape Reader that is very similiar, its a little bit different, but most likely the same or similiar Printed Circuit Board..
I have had it working with my Altair and with my Data General Nova Systems, but not a DEC.. I had asked about making it work on or with the DEC PDP a few years ago, but I got no response..
THANK YOU Marty
 
Lou - N2MIY said:
This does indeed seem like a good idea. Back in the day, if you had an ASR33 on your system, that was considerd a low speed reader/punch. I think you could easily make one of your PC04s work like an RS232 connected low speed reader/punch. It would share the console TTY DL11, because that's how the ASR33 was connected. The PC: bootstrap rom for the M9312 supports both the PC11 high-speed reader punch and the low speed reader punch.

There are probably more people than just you who have the PC04/05 but not the bus interface card. I think there would be a few people interested in building copies of your work.

I have a different but similar papertape reader project to work on. I recently also got a reader from an old CNC milling machine. I need to build exactly this device http://juliepalooza.8m.com/sl/remex.htm that Steve Loboyko built. I have exactly this reader. This is similar in scope to the reader half of your project.

Lou
Click to expand...

What I really had in mind was to make the OS believe it has a PC05 although it sits on a DL11 adapter, simply by rewiring it to use address 777550 and vector 70/74. What do you think of that? Would the DL11 and the PC11 be sufficiently similar to make the OS think it as an PC11? They sure look pretty similar to me at least, programming wise. The ERROR bit differs, but the rest?
 
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