GB770989A - Improvements in or relating to digital accumulators - Google Patents

Abstract

770,989. Statistical apparatus; counting apparatus. BRITISH TABULATING MACHINE CO., Ltd. Oct. 5, 1955, No. 28355/55. Drawings to Specification. Class 106 (1). An accumulator for use in a record card controlled machine is designed to receive entries represented on the cards in one scale of notation (e.g. decimal) and form a sum in a different scale of notation. The apparatus described is adapted to totalise amounts of money in Indian currency which involves receiving and adding amounts in annas. Since there are 16 annas to the rupee it is necessary for the adder to count up to 15 and then carry to the rupees order. The accumulator therefore, in order to be operable in a " 16 " scale of notation, has two accumulator orders in the form of wheels, one having eight positions recording 0-7 and the other having two positions recording zero or eight. This second wheel is called the " eights wheel." There are carry means between the order wheels and entry means for each order operable by values from the cards expressed in the decimal scale of notation. One of the entry means is effective to enter values of one denomination (0-7) into the first order wheel and the other entry means is effective to enter values of a higher denomination in both order wheels. Where a value between 10 and 15, say 13, is to be entered the second wheel (the eights wheel) registers the ten digit and the first wheel registers the " 3." But since the second wheel only represents 8, it is necessary to make a corrective entry into the first wheel, i.e. a value of two is added to its registration. The accumulator is also adapted for subtractive entries by the provision of means for entering the complement to seven of the digits 0 to 7 in the first wheel and for entering the complement to fifteen of the numbers 8 to 15 on the first wheel together with an entry on the second wheel to differentiate between the two ranges of complements. The complement to fifteen is entered by suppressing the tens digit and entering the complement to five of the units digit. The record cards are sensed in the manner described in Specification 623,283. The cards are passed through three stations, a presensing station, a control station and an adding printing control station. The two latter stations are provided with sets of brushes connected to contacts forming part of a commutator. The output from the commutator corresponding to a selected column of the card occurs at some point during the sensing cycle. The time within the sensing cycle at which it occurs is indicative of the digit value recorded in that column, thus a hole in the " 6 " index point position of the card will produce an output pulse at " 6 " digit time in the sensing cycle. The accumulator is similar to that described in Specification 675,223. Each order wheel can be selectively latched to a driving means (e.g. at " 6 " digit time) by the operation of an advance magnet and unlatched (at " 0 " digit time) e.g. by a stop magnet or mechanical knock-off. In this case the wheel will be driven through 6 digit positions and so will add 6 to the initial reading. To subtract a value from the amount standing in the accumulator the wheel is latched up at " 9 " digit (which is read out first on the card) and unlatched when the perforation is sensed (at " 6 digit time). Thus the wheel is driven through three digit positions and adds three-the complement to nine of six. Each accumulator wheel carries two brushes for reading out the value recorded. Each brush makes contact with a segment of a commutator, one commutator being. wired to give a true value read-out and the other wired to give a complementary value. An embodiment with reference to a circuit (not shown) is described in which there are latch advance and stop magnets for the accumulator wheel of the pies denomination (twelve pies=one anna) and corresponding magnets for the unit annas wheel and the eight annas wheel. The magnets are controlled by contacts of relays which are governed by the card reading brushes and the setting of the machine. The card is sensed at the second and third stations in two successive machine cycles. During the first cycle the pies and tens of annas columns are sensed at the second station and in the next cycle the pies, annas and tens of annas columns are sensed at the third station. This permits the value in the tens of annas to control the entry of the correction factor (two is added as described above) into the accumulator prior to the entry of the values sensed from the card.