I saw this: Learning to program on punchcards

and I've seen this: http://en.wikipedia.org/wiki/Computer_programming_in_the_punched_card_era

but they leave much to be desired.

Can anyone explain to me how programmers programmed when they used punchcards? Specifically, the system of input computers used to derive instructions from the punched card itself.

I do not know much about retrocomputers, so any one system of input you are familiar with would be fine. More general answers are also appreciated.