Unit record equipment

[1][2][3][4] Unit record machines came to be as ubiquitous in industry and government in the first two-thirds of the twentieth century as computers became in the last third.

They allowed large volume, sophisticated data-processing tasks to be accomplished before electronic computers were invented and while they were still in their infancy.

The operation of many machines was directed by the use of a removable plugboard, control panel, or connection box.

The term unit record equipment also refers to peripheral equipment attached to computers that reads or writes unit records, e.g., card readers, card punches, printers, MICR readers.

Punched card technology had quickly developed into a powerful tool for business data-processing.

The warning often printed on cards that were to be individually handled, "Do not fold, spindle or mutilate", coined by Charles A. Philips, became a motto for the post-World War II era (even though many people had no idea what spindle meant).

Unit record machines therefore remained in computer installations in a supporting role for keypunching, reproducing card decks, and printing.

Many organizations were loath to alter systems that were working, so production unit record installations remained in operation long after computers offered faster and more cost effective solutions.

Cost or availability of equipment was another factor; for example in 1965 an IBM 1620 computer did not have a printer as standard equipment, so it was normal in such installations to punch output onto cards and then print these cards on an IBM 407 accounting machine.

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.

The verifier operator re-keyed the source data and the machine compared what was keyed to what had been punched on the original card.

An activity in many unit record shops was sorting card decks into the order necessary for the next processing step.

These machines could merge or match card decks based on the control panel's wiring as illustrated here.

An interpreter prints characters on a punched card equivalent to the values of all or selected columns.

The columns to be printed can be selected and even reordered, based on the machine's control panel wiring.

The device was called an Electrical Remote Control of Office Machines and was assigned to IBM.

[83] The operation of Hollerith/BTM/IBM/Bull tabulators and many other types of unit record equipment was directed by a control panel.

[86] Control panels had a rectangular array of holes called hubs which were organized into groups.