Friday, July 3, 2015

This and that, mostly P390


The PCOMOS2 3270 program used on this system is somehow not passing the PA2 or Clear key codes to the running OS (VM/370) but instead resetting the session in a way that forces the user off the terminal and makes them log back in. It displays a PROG775 message as well. Ideally this gets fixed so that I can hit the clear key to move forward when a terminal screen sites in the "More" state.

For the time being, I have overcome this problem by changing the timing of the 'more' function down to 5 seconds from the default of one minute. It is much more tolerable this way.

I set up a DOS virtual machine to do the DOS/VS 34 sysgen from the distribution tape. I had to fight the P390 system to produce output files from the spooled printing that everyone insists on doing - DOS to VM to P390 to OS2. I see an error message for the standalone disk initialization step saying that X'150' is not a valid disk drive. Progress.

This is typical of mainframe systems - it can take a while to figure out what is not working right; it is an environment with quite limited feedback. Sometimes you have to go to the source code, look up what causes a given message to be issued, and then step through the disk or memory to locate the trigger. Even then, it may take a bit of inspiration to figure out how to fix it, although usually the course of action is clear by this point.

I continue to have to reconfigure the settings each time I power on, because the CMOS battery is dead and the replacement is meandering through the lazy, unreliable USPS system - listed online as due for deliver yesterday but no sign of movement since it hit Dallas five days ago.

Went through a few tests, changing things, but still getting the error on the initialize disk utility. After I shut everything down, it occurred to me that this might be a very simple issue that the card images I am sending to the virtual card reader are not a full 80 columns long. I am not sure of the behavior of the spooled card readers - if they pad then everything is good, otherwise it might be looking at garbage on the remainder of the card buffer, causing the error message.

Frankly, since the error concerns the suitability of the disk drive, it might be an issue with the emulation of the drive - lack of CE tracks or something. At this point, I could initialize the pack with a known good program, then skip over the utility on the tape to run the restore job.


I have heard from the owner of the 1800 system that he has been working on the 2311 disk drives as well as mastering the design of the 1800 processor itself. He just finished restoring a couple of ASR-33 teletypes and a Honeywell 316 minicomputer. His pictures of the cleaned up disk drive just sparkle - he has certainly cleaned it up superbly.


I can't find any manuals at all about the PP-8087/u rework station I have, which looks like it was built by Pace for the US military. I can't find a close enough equivalent Pace model to get the documentation. Unless I am lucky and find something that is causing it to fail to stay on, I may not be able to make use of this any more.


I have reloaded all the SDK code from scratch, used the files that worked properly at Richard's home, but they fail exactly the same here. This is quite frustrating.


  1. Carl,

    Is the 1800 owner blogging or posting pics about his progress on any web site?

  2. His sporadic blog entries are in Finnish, rendering the content mostly inaccessible. I do hear from him, in English, from time to time and I will reflect some of that here. I don't feel right publishing everything as I don't know his feelings about it.