IBM 1130 light panel wired up, powered up and okay at first cut; my DMS load deck isn't complete (yet)

WIRING MY MODIFIED LIGHT PCB INTO THE 1130 DISPLAY PEDESTAL

Because of the clunky design of the lighting components inside the 1130's display pedestal, replacing incandescent bulbs is very labor intensive, tedious and causes much frustration. To do away with the frustration, I designed a new approach to host the bulbs and circuitry that would allow for relatively quick and easy replacements.

The entire back of the honeycomb which houses more than 150 bulbs is covered by a single large PCB. it has sockets at each lamp location where I can plug in, and therefore replace, lights. The back of the PCB has the SCRs and wiring, plus the pins where each system signal is connected to drive its lamp on the display. 

I did extensive testing of this back in California, but not on the 1130 itself. I used a high current 7.5VAC transformer and wired up circuits to appear to be the Lamp Test and signal inputs. I was satisfied that all bulbs would light with Lamp Test switched on, as well as having the lamps individually controlled by SLT logic levels on the input pins. These levels swing between 0 for off and +3V for on but have a threshold for valid off and on values that I also had to honor. 

I had this temporarily mounted to the back of the honeycomb, then cut and connected power leads to bring the lamp test signal and the AC power from the terminal strip in the pedestal to my PCB. Once that was done, I thought it wise to test without having all the precious logic signals wired in, lest something blow up dozens and dozens of SLT cards.

POWER UP AND LAMP TEST TO CHECK FIRST FUNCTIONALITY

I brought up the machine and hit the Lamp Test switch. Everything was off with no logic signals connected and lit up when I did the test. I did see two bulbs that either are bent over or otherwise not lighting, but those can be handled later since almost everything else lit satisfactorily.

APPROPRIATENESS OF SIGNALS AND CIRCUITS DRIVING LAMPS

At that point, I plugged all the signals into the pins on my PCB. IBM's wonderful manufacturing practices were a tremendous help here. IBM carefully cuts all wires in a harness to their intended length and laces everything together, so that a bundle providing signals for 16 bits of a register have the pins arranged perfectly to plug in with no confusion. If this wasn't true, I might have had to beep out connections for more than 150 signals to get them on the proper pin. 

Laced harnesses make wiring easy

When I powered up, I could see reasonable and appropriate status lighting up. The machine responded to the buttons like Reset, Start and the rotary mode switch. The lamps light just as they did with the original IBM components, a key objective of my project to replace the lamp components. 

Running under Interrupt Level 0

MUCH IS WORKING PERFECTLY

I can see that most of the machine is working properly, a fairly large fraction, since it will single step through instruction execution and fetch memory contents without parity errors or other issues. When I hit the Reset button, the machine quickly jumps to a high address which I believe is the resident driver code for one of the peripherals. 

INITIAL ISSUE IS DUE TO HOT INTERRUPT REQUEST FOR LEVEL 0

I can see that something has a permanent request for interrupt on IL0, which forces the machine to branch to a location and execute code. Once I quell that request for interrupts, I can hand load some instructions and begin to more fully check out the system. It does appear to have survived its trip pretty well. 

LIKELY CAUSES, NO RED FLAG AT THIS TIME

There are two possible outside elements that can be causing this IL0 request. The 1442 Card Reader, while not cabled into the machine currently, does use IL0 to read each column as the card moves it over the photocells. I also added circuits for my FPGA based extender to drive IL0, so that it could provide a virtual 1442 to read and punch card images to PC. My bet is on the FPGA connection, since I didn't hook up the cable. 

HAD NAGGING FEELING MY CARD DECK FOR LOADING DMS V2M12 WAS TOO SHORT

As I thought about having three small boxes to load the entire DMS system on a freshly initialized cartridge, I felt the size was too small. I went to the digitized file for that tray and indeed the deck is not complete. Well, more later since it is complete just not for an initial load on a clean pack. 

There were quite a few phases missing in the deck. The first phase should be DUP phase 1 followed by 2 through 17. then all the phases for Fortran, Supervisor, Core Load Builder, I/O devices, Core Image Loader, DUP II, and the Assembler. Right away, phase 1 was missing, we had 2, 3, 5, 8, 9, and 10 so quite patchy.  

THIS IS ACTUALLY AN UPGRADE DECK, TO CONVERT A M11 PACK TO M12

This deck has a Mode card with R, which is reload, which means you apply it against an already loaded cartridge to reapply the selected phases in the deck. To understand why the particular phases were there and others were missing, I opened all the phases and looked at the header card which indicates the level when it was last modified. 

I found that the phases in the deck were all the phases that were changed going from V2 M11 to V2 M12, the latest version of DMS. I then realized that this was an upgrade deck. It would take a pack that had DMS V2 M11 loaded on it and, through the reload, bring it up to full V2 M12 level. 

WHAT I PLAN TO DO IN ORDER TO SELL A COMPLETE LOAD DECK

Potential buyers of the deck may include collectors and museums who have an IBM 1130 and want to have the full deck to run on a physical system. The chance that they have a M11 pack already and just need to upgrade is slim. Therefore, I want to build this up to be a complete initial load deck.

Since the missing phases are all from earlier levels of DMS, I can grab them from any of my decks, whether for V2 M11 or V2 M12. I have several such decks and should therefore be able to find all the older phase versions in them and assemble everything to a complete, current system deck.