Computer programming in the punched card era

Often another keypunch operator would then take that deck and re-punch from the coding sheets – but using a "verifier" such as the IBM 059 that checked that the original punching had no errors.

In smaller organizations programmers might do their own punching, and in all cases would often have access to a keypunch to make small changes to a deck.

IBM's huge size and industry footprint often caused many of their conventions to be adopted by other vendors, so the example below is fairly similar to most places, even in non-IBM shops.

An IBM 407 Accounting Machine might be set up to allow newly created or edited programs to be listed (printed out on fan-fold paper) for proofreading.

To solve that problem, the card reader could be reinstalled (or initially installed) outside of the computer room to allow programmers to do "self-service" job submission.

Many computer installations used cards with the opposite corner cut (sometimes no corner cut) as "job separators", so that an operator could stack several job decks in the card reader at the same time and be able to quickly separate the decks manually when they removed them from the stacker.

In later years, as punch card data was converted to magnetic tape files the sequence numbers were often used as a column in an array as an index value that can be correlated to time sequences, such as in the natural sciences where the data on the cards were related to the periodic output of a measuring device such as water stage level recorders for rivers and streams in hydrology, or temperatures in meteorology.