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Reviving the PDP-12 at the RICM

Hi All;

M-Thompson, "" Once we replaced the SP380 we were able to boot OS/8 from an RX01 floppy. This may be the only PDP-12 to ever do that. ""
Congratulations !!!
Hopefully, You can run the same Tests, that You were going to run from the TU55 or TU56, and then, that might help You find the problem(s).. So, that You can Run the TU55 or TU56..

THANK YOU Marty
 
Marty said:
Hopefully, You can run the same Tests, that You were going to run from the TU55 or TU56, and then, that might help You find the problem(s).. So, that You can Run the TU55 or TU56..

THANK YOU Marty
Click to expand...

The TC12 has the capability of testing almost every piece in the controller, and can even fake data coming from the tape heads. All of the TC12 controller diagnostics run fine and report no errors. The diags that format or write to a tape fail. The TU56 transport and the corresponding cable worked OK in the 8/I. The TU55 transport and corresponding cable borrowed from the 8/I show the same failure modes when installed in the PDP-12. We are just about out of ideas for what to try and test to get the TC12/TU56 working.

We decided to take a break from the LINCtapes and got the RX01 floppies working. We will work on the paper tape reader/punch next, then try the RK05 disk. Maybe after we get everything else working we will try the LINCtapes again.
 
Hi All;

M-Thompson, Thank You for Your answer..

The TC12 has the capability of testing almost every piece in the controller, and can even fake data coming from the tape heads.
I would be curious How it fakes data coming from the Heads..

I guess, that it shouldn't be to hard, I have a PDP 8i clone that fakes Data all of the time, it's getting it to produce true data that is the real trick..

THANK YOU Marty
 
Warren modified Kyle's SerialDisk OS/8 handler to remove the BSW instruction. We were able to boot OS/8 from and RK05 image from a disk server running on a laptop. We are now working on running BUILD to add the system and non-system SerialDisk handlers to OS/8. When we finish testing we will upload to the SerialDisk GitHub site.

Theoretically this should work on any PDP-8.
 
Thanks - that's a great tool for pre-8/E owners!

Maybe while Warren is warmed up and probing the innards of SerialDisk, he can take care of the interrupt enable/disable issue that prevents FRTS from working and thus Adventure from running.

Jack
 
Last edited:
jackrubin said:
Thanks - that's a great tool for pre-8/E owners!

Maybe while Warren is warmed up and probing the innards of SerialDisk, he can take care of the interrupt enable/disable issue that prevents FRTS from working and thus Adventure from running.

Jack
Click to expand...

If you run this before running FRTS it will work fine.
*200
PKIE=6405
CLL CLA
PKIE /CLEAR INTERRUPT
JMP I (7605
$
 
m_thompson said:
Warren modified Kyle's SerialDisk OS/8 handler to remove the BSW instruction. We were able to boot OS/8 from and RK05 image from a disk server running on a laptop. We are now working on running BUILD to add the system and non-system SerialDisk handlers to OS/8. When we finish testing we will upload to the SerialDisk GitHub site.

Theoretically this should work on any PDP-8.
Click to expand...

I've also been working on SerialDisk, cleaning up some bits on the server side. I found a way to reduce the overhead of the byte transmission, and receipt on the pdp8 side and it also is pre-8/e friendly.
 
Crawford said:
I've also been working on SerialDisk, cleaning up some bits on the server side. I found a way to reduce the overhead of the byte transmission, and receipt on the pdp8 side and it also is pre-8/e friendly.
Click to expand...

Warren added quite a bit of debugging code to the server. We should merge our changes to the handler and server. We can test with the 8k PDP-12, but only at 9600 baud on the server's serial port. I can test with my 32k 8/e with the server's port running at 38,400 baud.

We are having difficulty BUILDing an RK05 pack image that has the system and non-system handlers included. I think that this is mostly due to the 32k environment on the 8/e and trying to get the image to run on the 8k PDP-12. We have tried the MEMORY command when running on the 8/e to limit the memory that it uses to 8k, but it makes OS/8 do strange things. If you have already done this, then maybe you can send us a copy of your RK05 pack image.

My 8/e has the MI8E for RX8E boot. I am planning to modify BOOT to include support for SerialDisk so you can just BOOT/SD from any other media.
 
It sounds as though quite a few folks have been modifying Kyle's handy tool. Probably like Crawford above I removed the redundant CDFs and tightened a couple of other points as well as removing the BSWs. I also added the interrupt disable to stop Focal and Fiv from hanging when I forgot to clear the flag.

My version has 2 disks (4 'sides') in the system handler and 4 disks in the non-system handler with the server hacked to suit and seems to run fine on my 8/e and 8/a but I don't have a pre-omnibus machine to verify on.
 
bobaboba said:
My version has 2 disks (4 'sides') in the system handler and 4 disks in the non-system handler with the server hacked to suit and seems to run fine on my 8/e and 8/a but I don't have a pre-omnibus machine to verify on.
Click to expand...

I could give it a try on the PDP-12 on Friday.
 
I'll fetch a copy when things warm up a bit, it's -4 in the garage just now so I'm staying well clear. I have a 30kW heater out there though so when I've a bit of time I'll venture out and fire it up for a while. I don't switch any of the machines on when they're so cold.

What's the best way to send you a copy?
 
We replaced an M160 flip-chip and now the EAE instructions work. We replaced an M103 flip-chip and the KW12 clock works. This system is new enough that ECO EM12-0055 for the KW12 was installed when it was built. This means that the KW12 Maindecs earlier than D8CD will not work.

We cleaned up the PC04 paper tape reader/punch and connected it to the PC8E. The punch works OK, but the reader does not always step correctly and does not read the tape correctly. Fixing this will be the next project.

We found that the maintenance prints that came with the system do not include ECO EM12-0055.
Does anyone have a set of KW12 prints that include ECO EM12-0055?
 
We worked on the PC04 paper tape reader/punch some more. The ramp generator and triggered free-running multivibrator on the PC8E controller is supposed to slowly speed up and down the stepper motor that moves the paper tape so the tape does tear the feed holes. This one was ramping up nearly instantly, and the trimpot had no effect. It turned out that the -15V power supply in the DW8E expansion chassis that holds the PC8E controller had failed again. The fuse was blown so we replaced it. It worked for just a few minutes and failed again. After lots of debugging we decided that there was probably a bad solder joint on the PCB. We re-soldered every connection in the -15V part of the power supply. It works reliably now. The stepper motor in the paper tape reader works correctly now, but it still does not read data from the paper tape. That will be the next debugging project.
 
We got FOCAL-69 to run on the PDP-12.

We found a bug where FOCAL executed a 6762 instruction intended to initialize a TC01 DECtape controller. The 6762 instruction causes the Automatic Priority Interrupt controller on our PDP-12 to execute a hardware PUSH instruction using Data-Break and starts executing instructions in non-existent memory in field 2. We replaced the 6762 instruction at 4376 with a 7000 NOP and now FOCAL-69 runs OK.
 
We also got the paper tape reader/punch to work last week. It still needs some tuning to optimize the settings. Once that is completed we will start diags on the RK05 controller.
 
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