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PUNCHED CARDS

PUNCHED CARDS
There were two sorts of punched card systems: manual and electronic.

MANUAL PUNCHED CARDS
The manual systems consisted of cards with holes near the edges, through which a needle could be inserted. Each hole represented a different category in a data-base and the edge of the hole was cut away if that category was relevant to a particular card.

When the cards were lifted with the needle inserted into one hole, those cards with the edges of that hole cut away would fall out.
The needle could then be inserted into another hole in this sub-set to further refine the selection.
The cards could be stored in any order

Many thanks to Brian Davies, Aberystwyth for the detailed explanations and loan of the manual punched cards. 

ELECTRONIC PUNCHED CARDS

These cards were used to store and sort information using an early computer, before digital data-bases (such as Microsoft Access and more refined systems) became available.

The cards were punched by an operator using a machine. Some systems had a method of checking that the information had been accurately entered.

Many thanks to Philip Thomas of Derby for supplying the detailed account of how these machines were used.