Editing Unit record equipment (section)

==Punched cards==

{{main| Punched card}}

<!-- "...each column represented..." applies to the 80 column card and some other cards, but not all cards -->
The basic unit of data storage was the [[punched card]].  The IBM 80-column card was introduced in 1928. The Remington Rand Card with 45 columns in each of two tiers, thus 90 columns, in 1930.<ref name=Gill>{{cite book |author= Gillespie, Cecil  |title= Accounting Systems: Procedures and Methods, Chapter 34: Equipment for Punched Card Accounting |publisher= Cowen Company, Boston |year= 1951 |pages =684–704}}</ref>  Powers-Samas punched cards include one with 130 columns.<ref>(Cemach, 1951, pp 47-51)</ref>  Columns on different punch cards vary from 5 to 12 punch positions.
 
The method used to store data on punched cards is vendor specific.  In general each column represents a single digit, letter or special character. Sequential card columns allocated for a specific use, such as names, addresses, multi-digit numbers, etc., are known as a field. An employee number might occupy 5 columns; hourly pay rate, 3 columns; hours worked in a given week, 2 columns; department number 3 columns; project charge code 6 columns and so on.