page_title: Unit record equipment
section_title: Control panel wiring and Connection boxes
hierarchical_section_title: Unit record equipment / Control panel wiring and Connection boxes
context_page_description: Starting at the end of the nineteenth century, well before the advent of electronic computers, data processing was performed using electromechanical machines called unit record equipment, electric accounting machines or tabulating machines.
  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. This data processing was accomplished by processing punched cards through various unit record machines in a carefully choreographed progression. This progression, or flow, from machine to machine was often planned and documented with detailed flowcharts that used standardized symbols for documents and the various machine functions. All but the earliest machines had high-speed mechanical feeders to process cards at rates from around 100 to 2,000 per minute, sensing punched holes with mechanical, electrical, or, later, optical sensors.
context_section_description: The operation of Hollerith/BTM/IBM/Bull tabulators and many other types of unit record equipment was directed by a control panel. Operation of Powers-Samas/Remington Rand  unit record equipment was directed by a connection box.
  Control panels had a rectangular array of holes called hubs which were organized into groups. Wires with metal ferrules at each end were placed in the hubs to make connections. The output from some card column positions might connected to a tabulating machine's counter, for example. A shop would typically have separate control panels for each task a machine was used for.
  Note: Control panel wiring is sometimes referred to as programming, however that term applies only to the control panels of calculators, such as the IBM 602 and IBM 604, that specified a sequence of operations.
caption: IBM 402 Accounting Machine control panel[84]
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