Patent GB-564839-A (GB)
Title: Improvements in or relating to multiplying and dividing machines
IPC: G06F7/46
Filed: 1943-02-10
Abstract: 564,839. Statistical machines. BRITISH TABULATING MACHINE CO., Ltd. Feb. 10, 1943, No. 2256. Convention date, Feb. 11, 1942. [Class 106 (i)] A machine adapted both to multiply two numbers together and record their product and to divide one number by another number and record the quotient is characterised by means operable after obtaining the product of two factors for dividing the product by one of its factors and finding the difference between the quotient and the other factor, while retaining the product in a counter, and for disabling the operation of the recording device if the said difference be not zero. The machine is also adapted, after obtaining the quotient of a dividend by a divisor and a remainder (which may be zero), for finding the difference between the dividend and the sum of the remainder and the product of the divisor and the quotient, while retaining the quotient in a counter, and for disabling the operation of the recording device if the said difference be not zero. The invention is applied to the type of machine described in Specification 532,109. The numbers to be operated on are punched on cards fed one by one past two sensing stations, the first sensing the location of the first significant figures only, the second sensing all the numbers electrically. After computation has been effected and checked, the result is punched in the card. The machine has six counter units, ML, MP, LQ, RD, SP, as in the prior Specification and a further unit PQ, all driven by gearing from a motor M. ML is a multiplicand (or divisor) unit consisting of six counters ML1-2, ML3-5 &c. as shown diagrammatically in Figs. 11 and 12. MP is a register to receive the multiplier. LQ and RD receive components of the products, that in RD being transmitted to LQ to provide the final product. In division, LQ receives the quotient and RD the dividend. In the checking process, PQ takes the place of LQ, while SP stores amounts for checking. The counters are of known type ; the carry and reset are effected electrically. The readout is electrical and as in Specification 532,109, from some of the ML counters, twice the amount can be read out. The cam contacts CC1-49, XC1-12 and FC2-14 and eight impulse emitters shown generally as 314 are of known type. The comparing units CU are of the type described in the prior Specification in which a circuit is established if a number entered on the one side AZ (not shown) is equal to or less than the number on the other side AW (not shown). A variable plugboard of known type, Figs. 7, 8 (not shown) is employed, selected sockets being connected for the respective operations of multiplication and division. The counters are reset by sending out complementary impulses from an emitter such as 314 wired in a way complementary to the readout devices, to the setting magnets, unity being added in the transfer part of the cycle. Multiplication with checking. On operation of a start key, the first card is fed from the magazine and the numbers to be multiplied are first sensed for the location of the first significant figures, and then fully analysed. In the manner described in Specification 532,109, all nine multiples of the multiplicand (MC), e.g. 358 are built up and represented in the ML counters and MLR readout devices. The multiplier (MP), e.g. 147 is entered into the MP counter. The RD and LQ counters collect the partial products due to alternate denominations in the multiplier, the whole being gathered in known manner into counter LQ. For checking by division, the product is read out from LQR and repeated in counter RD, while being retained in counter LQ. The multiplies of the multiplicand are cleared from counter ML and the multiples of the multiplier are built up therein. The multiplicand MC, after storage in counter SP is transferred as a tens complement to counter PQ. Division takes place in known manner, comparison being effected through the CU units to find the greatest divisor multiple which is not greater than the portion of the dividend being used at any moment. The complement of this registered divisor multiple is passed from its related readout to counter RD to effect subtraction from the said portion of the dividend, and the appropriate quotient is entered into counter LQ. Counters PQ and RD are tested for the zero status which would indicate a correct multiplication process. If both are at zero the product is punched. Division with checking. The quotient and remainder produced by division are checked by multiplication before the result is recorded. A denomination shift is effective for entries into counters ML, SP and RD, the first significant figure being entered into the second denomination in ML and in the extreme left in RD and SP. The multiples of the divisor are built up in the MLR readouts and the-dividend is entered into counter RD. In the manner described above, division takes place, the quotient appearing at the extreme left hand counter LQ. When the divisor will no longer go into the dividend, relay Y (not shown) energises to reset counters RD and ML during the next cycle. During the reset of RD the remainder is subtracted from SP by complementary addition. The machine is automatically conditioned for checking by a multiplication. The quotient is entered as a multiplicand into the ML counters while being retained in counter LQ. The amount in SP, e.g. 833 is given an appropriate denominational shift and subtracted from the cleared counter RD. Multiplication takes place as before except that the total is accumulated in PQ instead of LQ. At the end of the operation, if a test impulse reveals zero in counter PQ, the quotient in the readout LQR is punched in the record card. Errors in computation or punching are indicated in the same manner as in multiplication. Circuits are traced in full. Punching mechanism. Punching mechanism is of the customary successive column acting repetition punching type, punching being effected denomination by denomination, starting with the highest order. Upon energisation of a clutch trip magnet the card is fed into a position where its trailing edge is engaged by a card pusher 583, Fig. 13, attached to a rack 582. Detachably secured to the rack 582 is a skip bar 616 with a notch 617 covering the positions in which it is desired to punch the computed value. The rack 582 moves quickly to the left until a skip lifter 618 falls into the notch 617 to allow a dog 614 to engage the teeth of the rack. The rack now moves intermittently to the left under the control of an escapement 613, until the end of the notch is reached when the rack completes its leftward movement quickly. Secured to the rack is a set of brushes 623, 623a for co-operation with contacts 621 and contact strips 622, 622a. Overlying the card carriage is a set of punches 619 and, two columns away, a set of sensing brushes 651, Fig. 14. A circuit through strip 622, brush 623, the corresponding denominational contact 621, the LQR readout segments and through the corresponding punch selecting magnet operates the appropriate punch 619 of the highest denomination. Similarly after the card has moved one space the next denomination is punched, but before the third denomination is punched the first hole is checked against the LQR readout by a circuit through strip 622a, brush 623a, the first denominational contact 621 in the lower row, the LQR readout, and the corresponding punch checking brush 651 through the punched hole to a common bar 650. If the test is satisfactory punching proceeds. If unsatisfactory, a relay BA (not shown) fails to energise, punching ceases and the card remains in punching position. The operator must then depress a release key which causes the card to be ejected in known manner for examination. If the counters PQ or RD after checking multiplication, or the counter PQ after checking division, are not cleared, a relay A (not shown) fails to energise and there is no circuit to the punch selecting magnets. In this case, the card is spaced past the punches and ejection takes place. Feeding of the next card is also prevented so that the first card can be examined for faults.