Tuesday, December 30, 2014

Keypunch interface testing wrapped up, keypunch itself needs work

Our electrical utility, PGE, scheduled today to replace transformers serving my neighborhood, leaving us without power for a majority of the day. Got to work once I could, but progress limited as a result.


I rewrote the parsing of the punch line and am now pleased with the code. The earlier implementation was clunky, easily misunderstood and complex to maintain. Testing resumed once power was on.
Routine worked very well, thus could blast through the tests and finish up the remaining steps.

Interface under final test

The remaining two issues I found may be mechanical issues in the keypunch, they both have to do with the card in the read station registering and staying in column sync with the card moving through the punch station. A few times when I tested the _R read command I found some erratic initial movement, often generating one or two false columns before reading the rest of the card.

Verify mode suffered from the same defects, thus the card in the read station was a couple of columns behind the punch station card (and thus behind the logic of the interface which times everything to the punch station card column.

At this point, I will close up the interface box with its current software, since it is probably working correctly, and turn my attention to rehabilitating the keypunch.


I opened the cable connector, but there were no wires disconnected inside. I tried to clamp the connector on the thick vinyl outer cover of the cable but it was very difficult to accomplish since the internal wiring inside the connector exerts tremendous back pressure when I try to compress all the twisted pairs. When they are in their rest state, the clamp is about one half inch past the end of the vinyl and could instead compress twisted pairs if tightened.

Cable not secured by clamp on connector
I need at least four hands, two to push the cable into the connector, another to twist the connector to make the clamp screws accessible, and the last to operate the screwdriver. I will try to get someone to help tomorrow.

I see a couple of female pins pushed in on the socket, not as many as the peak of problems I saw on prior removals but still not good enough to complete all circuits. Once I fix the clamp on the cable, and push the errant female pins into position more firmly, I will try to reconnect the cable again.

1 comment:

  1. Carl, on this last day of the year I would like to thank you for persisting with your project but especially for persisting with this blog, which is one of my favorite bits of reading each morning! I enjoy sharing your efforts this way and look forward to all the progress you'll report in the next year.