Massive time waste - circuit different than ALDs - but made significant progress

 CLUE FROM MY EARLY NOTES

When I surveyed the cards in the 1130, I listed an 0509 in slot B3 rather than the 0000 that every copy of ALDs that I have seen lists. I also had spotted an 0000 card in slot F6 which is not part of the 1132 nor the 2501 controller logic pages. The 0509 provides ten inverters while the 0000 is six NAND gates, so quite different.

This in fact explains the lack of connectivity to most of the pins of B3 from B2. Today I traced the wirewrap that IBM applied to the machine in the area of B2 and B3. I found many signals running from B2 down to slots F6 and M6. I had noticed an 0000 in the spot and that gate matches the pin usage well. 

I painstakingly worked out the actual wiring for the machine and knew that all my repairs with wirewrap were wrong. I pulled all the wires off and inserted an 0000 in F6. The machine came up without the continual carriage spacing issue! No more spurious interrupt on level 1! It did respond to pushes of the Carriage Space button on the printer too. 

The status from a Sense DSW still showed carriage space busy, however, which is not correct. I did try executing an XIO command to drive a space of the printer - that worked perfectly but did not raise the interrupt since the controller needs the carriage space busy signal to turn off before it triggers the interrupt. 

DEBUGGING THE CARRIAGE SPACE BUSY LATCH

It appeared that part of the carriage space busy latch was implemented in the M6 position. One that I did not note as having a card present when I first examined the machine, but that could be an error on my part.

I will spend the afternoon tracing out the gates for this latch and watch signals until I find the flaw and correct it. 

WHAT WORKS WELL ALREADY

I have already verified that an XIO Sense DSW returns appropriate status bits, at least for carriage movement, carriage brush 1-12 state, absence of paper forms and line space operation completion. We know interrupts happen on IL1 for these conditions. Presently I have a jumper installed that blocks the interrupt but I removed that to move forward. 

I also operated the manual line space button which does advance the carriage one line position. Finally, I proved that the logic for entering the Ready state performs properly when the Start button is pressed as long as the motor is switched on.