page_title: Counter (digital)
section_title: Mechanical counters
hierarchical_section_title: Counter (digital) / Mechanical counters
caption_attribution_description: English: A scene from the U.S. Social Security Administration (SSA)'s early accounting operations in Baltimore circa 1936. The issuing of Social Security numbers and the creation of earnings records on all Americans covered by Social Security was the largest bookkeeping operation in the history of the world.
context_page_description: In digital logic and computing, a counter is a device which stores the number of times a particular event or process has occurred, often in relationship to a clock. The most common type is a sequential digital logic circuit with an input line called the clock and multiple output lines. The values on the output lines represent a number in the binary or BCD number system. Each pulse applied to the clock input increments or decrements the number in the counter.
  A counter circuit is usually constructed of a number of flip-flops connected in cascade. Counters are a very widely used component in digital circuits, and are manufactured as separate integrated circuits and also incorporated as parts of larger integrated circuits.
context_section_description: Long before electronics became common, mechanical devices were used to count events. These are known as tally counters. They typically consist of a series of disks mounted on an axle, with the digits zero through nine marked on their edge. The right most disk moves one increment with each event. Each disk except the left-most has a protrusion that, after the completion of one revolution, moves the next disk to the left one increment. Such counters were used as odometers for bicycles and cars and in tape recorders, fuel dispensers, in production machinery as well as in other machinery. One of the largest manufacturers was the Veeder-Root company, and their name was often used for this type of counter.
  Hand held tally counters are used mainly for stocktaking and for counting people attending events.
  Electromechanical counters were used to accumulate totals in tabulating machines that pioneered the data processing industry.
caption: Early IBM tabulating machine using mechanical counters
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