Wednesday, December 29, 2021

Had to whip up a card reversing program for decks read prior to my right hand notch modification

 HOW I READ SOME DECKS WITH RIGHT HAND NOTCHES BEFORE MAKING THE MOD

I took the deck and flipped it so that the last card entered the reader first. That also reversed the columns so that column 80 seems to be 1, 79 is in the place of 2, etc. I read the two decks but soon thereafter the jam and belt failure took place. 

I won't need to do this any more, since I have made the modification that protects the reader from false Read Checks caused by light passing around the diagonal notch on the right side and reaching the 12 zone photocell when the card is at the equivalent of column 81. This mod just forces row 12 to be dark at the column 81 time so the error check passes, but if any other row is illuminated then it is a legitimate error that should be flagged. 

QUICK PYTHON PROGRAM TO REVERSE EVERYTHING

I wrote a Python program that seeks to the last card of an input file, reads a card image, then backs up to the prior card position repetitively. I take the 160 bytes of binary data representing the 80 columns and access them in reverse, writing to an output file in the corrected order. The output file will thus have the cards in the proper order, first to last, and have the columns in the correct order, 1 to 80 from left to right. 

The two decks were processed. I did save the program just in case I ever need it or something similar in the future, but that should be the last time I need to process cards this way. 

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