control panel, could do both addition and subtraction of selected fields to one or more counters and print each card on its own line. At some signal, say a following card with a different customer number, totals could be printed for the just completed customer number. Tabulators became complex: the IBM 405 contained 55,000 parts (2,400 different) and 75 miles of wire; a Remington Rand machine circa 1941 contained 40,000 parts. Calculating In 1931, IBM introduced the model 600 multiplying punch. The ability to divide became commercially available after World War II. The earliest of these calculating punches were electromechanical. Later models employed vacuum tube logic. Electronic modules developed for these units were used in early computers, such as the IBM 650. The Bull Gamma 3 calculator could be attached to tabulating machines, unlike the stand-alone IBM calculators. Card punching Card punching operations included: Gang punching - producing a large number of identically punched cards—for example, for inventory tickets. Reproducing - reproducing a card deck in its entirety or just selected fields. A payroll master card deck might be reproduced at the end of a pay period with the hours worked and net pay fields blank and ready for the next pay period's data. Programs in the form of card decks were reproduced for backup. Summary punching - punching new cards with details and totals from an attached tabulating machine. Mark sense reading - detecting electrographic lead pencil marks on ovals printed on the card and punching the corresponding data values into the card. Singularly or in combination, these operations were provided in a variety of machines. The IBM 519 Document-Originating Machine could perform all of the above operations. The IBM 549 Ticket Converter read data from Kimball tags, copying that data to punched cards. With the development of computers, punched cards were also produced by computer output devices. Collating IBM collators had two input hoppers and four output pockets. These machines could merge or match card decks based on the control panel's wiring as illustrated here. The Remington Rand Interfiling Reproducing Punch Type 310-1 was designed to merge two separate files into a single file. It could also punch additional information into those cards and select desired cards. Collators performed operations comparable to a database join. Interpreting An interpreter prints characters on a punched card equivalent to the values of all or selected columns. The columns to be printed