Key punch: Meaning (information, definition, explanation, facts)

A key punch is a machine for manually entering data onto punch cards. The key punch looked like a small desk. It had a keyboard similar to a typewriter and hoppers for blank and punched cards. Later model key punches printed the value of each column punched at the top of the card. In some cases decks of punched cards were then sent to a second machine called a verifier, which looked a lot like a key punch. Its operator entered the exact same data as the keypuncher, but the verifier machine merely checked to see if the data was the same. Valid cards had a small notch punched on the right hand edge.

Key punch machines could be programmed by wrapping a specially punched IBM card around a small metal drum. The patterns of holes on the drum card could control tabbing and automatic duplication of fields from the previous card, among other things.

Post-WW II IBM Key punches for 80-column cards

IBM 024

Basic keypunch with no printing.

IBM 026

This key punch could print the encoded character above each column. There were two popular versions with slightly different character sets. The scientific version printed parentheses, equal sign and plus sign in place of four less frequently used characters in the commercial character set: percent, lozenge, pound, and ampersand.

IBM 029

Introduced with System 360, the 029 had new character codes for parentheses, equal and plus as well as other new symbols used in the EBCDIC code.

IBM 129

Transistorized key punch with many more features