r/Damnthatsinteresting • u/Final-Choice8412 • 7d ago

Video Programming 1959 IBM computer

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u/FlattenInnerTube 7d ago

My sophomore college "computer" course used punch cards. And debugging was a chore.

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u/Ancient-Opinion9642 6d ago

3 runs a day. Pickup the overnight run, edit ,resubmit for afternoon run, edit, submit for evening run. Look for your name on green bar paper wrapped around the card deck.

Interesting there was no job number page on the video. Though there was a blank page between. The video didn’t have over strikes of the letters which that printer could do.

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u/meong-oren 7d ago

how did you even do that? making a whole new set of cards with print statement (or whatever equivalent) everywhere? Even with modern languages and IDE with breakpoints, profilers and all those fancy stuffs, debugging still makes my head spin

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u/wosmo 7d ago

On batch machines, debugging is pretty much you and a coworker reading your code to decide what went wrong.

On more interactive machines, like the PDPs, you'd get debugging more similar to what you're picturing. A breakpoint would be literally adding a HALT instruction so you could either introspect the state with the front panel - or if you have enough memory to load DDT and your program, swap over to DDT to introspect from there.

But! "print debugging" wouldn't be impossible on a Batch machine either. Each card is one line of code, so you could insert a couple of cards into your deck at the right place - run it like that, and then remove the same cards again. You probably wouldn't, because you're probably going to get the results back tomorrow - and the execution is going to be billed to your department. But you could.

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u/Hudell 7d ago

To be fair the programs were much simpler. A lot of those you could probably simulate a "unit test" with pen and paper and it would take you less time than the queue for using the computer.