Repairing an IBM Model 029 Card Punch Keyboard

It’s easy to forget how difficult it was before the days of inexpensive electronics and actuators to do simple things, like preventing an operator from striking another key before the last one had done its bit(s).

Back in the day, I punched tens of thousands of cards on one of these IBM Model 029 card punches and its predecessor, the Model 026 (introduced in 1949!—the 029 dates from 1964).

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The 029 keyboard looks like it’s a free-standing unit, but it is connected to the punch by cables that pass through a hole in the desk and has limited movement. Curiously, the 026 keyboard was free-standing.

Here is Ken Shirriff’s wonderful blog post on how the 029 keyboard encodes key presses into combinations of holes in cards.

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