Patent GB-1011201-A (GB)
Title: Book-keeping machine
IPC: G06F7/44
Filed: 1962-04-30
Abstract: 1,011,201. Electric digital multiplication apparatus. SIEMAG FEINMECHANISCHE WERKE G.m.b.H. April 30, 1962 [April 29, 1961], No. 16330/62. Heading G4A. In multiplication apparatus, the multiplication is performed by multiplying together single digits of the multiplier and the multiplicand, the digit pairs being selected in groups, each group corresponding to a particular product order, the product thus being built up digit-by-digit commencing with the lowest order. Means are provided for eliminating automatically the calculation of digit products corresponding to non- significant zeros. In operation, the multiplicand is set up on a keyboard (not shown) thereby differentially positioning horizontal conductive links VA each to effect contact with one of ten digit value bars 0-9 in a set F1 which thus effectively stores the multiplicand. A " multiply " key (not shown) is depressed, and the multiplier is entered on the keyboard and set up in a second set of bars F2 constituting a multiplier store. The multiplier and multiplicand may be printed by a printer such as a typewriter. Fig. 2 shows a multiplicand 87963 and multiplier 483 set up in respective stores F1, F2. The multiplication operation is controlled by chains of electromagnetic relays and requires a plurality of cycles, each cycle resulting in the formation of a product digit and requiring one or more sub-cycles each sub-cycle corresponding to the multiplication of a multiplier digit and a multiplicand digit, the process being illustrated schematically (for a 4-digit multiplier and 5-digit multiplicand) in Fig. 3 (not shown). The multiplication operation is initiated after entry of the multiplier by the operation of a relay KA thereby effecting (1) the energization of the first relays A1, B1 in control chains A1-A9, B1-B9; (2) the energization of those relays DA2-DA9, which correspond to zeros (other than in the units order) in the multiplier and multiplicand; and (3) the energization of the first relay SS1 in a stepping chain SS1-SS9. The relay chain A1-A9, B1-B9 control contact fields a 1 -a 9 , b 1 -b 9  connected as shown to the multiplier and multiplicand stores F1, F2. The first cycle consists of one sub-cycle only, contacts a 1 , b 1  and ss 1  being closed to energize bars corresponding to the units digits in stores F1, F2, the conclusion of the digit multiplication 3 x 3 (which is effected by means not described) being signalled by momentary closure of a sub-cycle controlling contact e, the simultaneous change over of contact nd1 of a cycle control relay ND causing the relay SS1 to remain energized to initiate the next cycle during which relays A2, B1 are energized. The calculated units product digit is applied to the machine output. The second cycle comprises two sub-cycles corresponding to the energization of relays SS1, SS2 in which the products 8 x 3, 3 x 6 are calculated and summed, the resulting tens product digit being supplied to the machine output. In the third cycle relays A3, B1 are energized and three subcycles correspond to the energization of relays SS1, SS2, SS3 are required. Due to the energization of relay DA4 (there being no thousands digit in the multiplier), a circuit is now completed to energize relay B2 instead of B1 so that in the fourth cycle contacts a3, b2 are effective and the units multiplicand digit is not scanned. In the fifth cycle, relays A3, B3 are effective and in the 6th and 7th cycles, relays A3, B4; A3, B5, the multiplication then being terminated by the enegization of a relay MB over a circuit including closed contact db6c of relay DB6 energized since the 10<SP>5</SP> digit of the multiplicand is zero. Specification 792,342 is referred to.