The IBM 407 Accounting Machine, introduced in 1949, was one of a long line of IBM tabulating machines dating back to the days of Herman Hollerith. It had a card reader and printer; a summary punch could be attached. Processing was directed by a control panel. The 407 was the central component of many unit record equipment shops which were the mainstay of IBM's business at the time. It could print digits, letters and several special characters in any of 120 print positions, spaced . In 1976 the IBM 407 Accounting Machine was withdrawn from marketing. Description The 407 read punched cards, totaled fields on the cards, made simple decisions, printed results, and, with the aid of a summary punch, output results on punched cards that could be input to other processing steps. The operation of the 407 was directed by the use of a removable control panel and a carriage tape. Exit hubs (impulse emitting) on the control panel are wired to entry hubs (impulse accepting) for the task to be done (see Wiring of unit record equipment). There are hubs for each card column (at both reading stations), print position, counter digit, and so on. Logic tests were also available. Each input card was read at two successive reading stations. Thus, for example, fields in a card could be compared with the following card and, should a change be detected, say in invoice number, totals could be printed. Unlike earlier IBM tabulating machines, which had 80 read brushes at each read station, one for each column, the 407 had 960 brushes at each station, one for each possible hole in a punched card. Cards were held in position during each read cycle and the per digit pulses needed were generated using commutators, one for each column. This allowed the card to be read more than once at each station, for greater flexibility. For printing, the 407 used type wheels, an improvement over earlier tabulators that used print bars. The 48-character wheels were stationary until a character impulse was to be printed; the wheel then rotated in two steps. the first step rotated each wheel to one of 12 groups of characters based on the digit impulse associated with that print position. Digit impulses included the digits 1 through 9 (in reverse order), the 8-3 and 8-4 combination punches and a group (N) for no digit impulse. One of