Punched card sorter
A Punched card sorter is a machine for sorting decks of punched cards. Sorting was a major activity in most facilities that processed data on punched cards using unit record equipment. The work flow of many processes required decks of cards to be put into some specific order as determined by the data punched in the cards. The same deck might be sorted differently for different processing steps. A popular family of sorters, the IBM 80 series sorters, sorted input cards into one of 13 pockets depending on the holes punched in a selected column and the  sorter's settings. Basic operation. The basic operation of a card sorter is to take a punched card, examine a single column, and place the card into a selected pocket. There are twelve rows on a punched card, and thirteen pockets in the sorter; one pocket is for blanks, rejects, and errors. Cards are normally passed through the sorter face down with the bottom edge ("9-edge") first. A small metal brush or optical sensor is positioned so that, as each card goes through the sorter, one column passes under the brush or optical sensor. The holes sensed in that  column together with the settings of the sorter controls determine which pocket the card is to be directed to. This directing is done by slipping the card into a stack of metal strips (or "chute blades") that run the length of the sorter feed mechanism. Each blade ends above one of the output pockets, and the card is thus routed to the designated pocket. Sorting operations. Multiple column sorting was commonly done by first sorting the least significant column, then proceeding, column by column, to the most significant column. This is called a least significant digit radix sort. Numeric columns  have one punch in rows 0-9, possibly a sign overpunch in rows 11-12, and can be sorted in a single pass through the sorter. Alphabetic columns have a zone punch in rows 12, 11, or 0, a digit punch in one of the rows 1-9, and can be sorted by passing some or all of the cards through the sorter twice on that column. For more details of punched card codes see Punched card#IBM 80-column punched card formats and character codes. There were several methods used for alphabetical sorting, depending on the features provided by the  particular sorter and the characteristics of the data to be sorted. A commonly used method on the 082 and earlier sorters was to sort the cards twice on the same column, first on digit rows 1-9, then on the zone rows 12, 11, and 0 (or vice versa, zone rows first then digit rows). Operator switches allow zone-sorting by "switching off" rows 1-9 for the second pass of the card for each column. Other special characters and punctuation marks were added to the card code, involving as many as three punches per column (and in 1964 with  the introduction of EBCDIC as many as six punches per column). The 083 and 084 sorters recognized these multiple digit or multiple zone punches, sorting them to the error pocket. Earlier sorters. Original census sorting box, 1890, manual. Sorting cards became an issue during the 1900 agricultural census, so Herman Hollerith's company developed the 1901 Hollerith Automatic Horizontal Sorter, a sorter with horizontal pockets. In 1908, he designed the more compact Hollerith 070 Vertical Sorting Machine that sorted 250 cards per minute. The Type 71 Vertical Sorter came out in 1928. It had 12 pockets that could hold 80  cards. It could sort 150 cards per minute. The Type 75, Model 1, 19??, 400 cards per minute The Type 75, Model 2, 19??, 250 cards per minute IBM 80 series Sorters. Card Sorters in the IBM 80 series included: In August 1957, a basic 082 rented for $55 per month; an 083 for twice that. By 1969, only the 82, 83 & 84 were made available for rental by IBM.