THE PUNCH CARD FILE
A file is composed of several punched cards to allow the memorization of informations about a domain (stock, accounting… ), and to be processed by different machines in the mechanographical workshop. A card has 80 columns of 12 lines, representing 80 alphanumeric characters :
one perforation per column for a number
two perforations per column for a letter
It is necessary to distribute data across multiple cards if all data on a field has more than 80 characters. The card code (C/C), generally perforated on the first columns of the card, is used to differentiate cards from a same referent. According to the data they contain, there are three types of cards : Master card : Identifies a referent, and has most of the time constant data and variables which are specific (product number, designation, stock quantity … ) Detail card : Contains the information needed to edit documents that reflect a new situation of a referent and eventually produce a summary card for cyclical work ( salary statement, stock card, invoices, indents … ) Summary card : Created following a specific treatment, (Ex : update store stock), it allows to get the constant data of the Master card and the updated data from the treatment. That card will become the Master card for the next treatment. Example : treatment of ”Update store stock” 