Tuesday, October 14, 2014

Working the last vestiges of sludge out of the gummed up 1053 printer and continuing the software development for the keypunch interface


I cleaned up and applied more grease on the carrier rails, then oiled other parts of the mechanism. It is still erratic and my suspicions are turning to the contacts and micro-switches that inform the adapter when a print operation reaches certain stages. With all the other contacts in the 1130 that had oxidized into permanent off switches, I need to check all the circuits for continuity.

I did notice that the right margin  and end of line detection is a bit erratic. From time to time it doesn't trigger the carrier return or index, just typing to the end of the platen and chattering away in place. This is likely to be sticky old lubricants as well. After some work with oil and exercising joints, it is much better, including a clear bell ring on reaching the right margin, but it still fails to trigger the CR once in a while. More work with lubricants, cleaners and repeatedly hand moving all the moving and sliding parts.


I completed all the command validation code, leaving just the execution of the commands to implement. By early evening, I had about three quarters of the execution logic coded as well. The main part still remaining has to do with when to fire the punch or space relays and when to release them.

I am looking for a means to determine when to drop the punch relays - I could use a fixed time but it would be better to watch something like the cam contacts which operate at fixed points during a punch cycle. I could add a wire to the punch cable, hooked to a reed switch around the escapement relay, which would give me a pulse right at the 180 degree point of a punch cycle just as the card prepares to move to the column that will be punched. However, I am not sure what happens during a multipunch.

Some scoping of the machinery and testing of code is probably necessary to get this to work as intended. I am going to write the final execution code with pseudocode in place of the timing delays or condition tests, allowing me to finalize it once I have done tests with the keypunch.

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