Patent GB-733350-A (GB)
Title: Electrical apparatus for the production of electrical impulses representing the product of two numbers to be multiplied
IPC: G06F7/52
Filed: 1952-03-20
Abstract: 733,350. Digital electric calculating-apparatus. COMPAGNIE DES MACHINES BULL. March 20, 1952 [March 30, 1951], No. 7236/52. Addition to 732,902. Class 106 (1). In electrical multiplying apparatus including an electronic serial adder according to the parent Specification, in which the multiplicand is represented by a binary pulse train and the multiplier is a decimal number expressed in binary form, the initial multiplicand train is changed into differently delayed trains by delay elements connected to an input terminal of the adder, each delay element being adapted to delay the initial train by a different fraction of a binary period and by an integral number of binary periods, this number being chosen in accordance with the corresponding one of the binary terms of the multiplier. As described, a'binary number A is multiplied by a decimal number B by combining devices for multiplying by any digit 1-9, such as that shown in Fig. 1, with devices for multiplying by power of ten, such as those shown in Figs. 2 and 6. Fig. 1 shows a three-number adder as described in the parent Specification, including trigger ciicuits 20, 21 and 40 for registering the sum digit and carry digits respectively, the triggers being reset at the end of each digit period by timing pulses at T which also produce carry pulses on lines 31, 44 and the " sum " pulses at S. The pulse train representing A is applied at E to produce, through delay elements, 25, 26, 38, 65 having values formed from the digit period p and the delay period t = 1/6 p, four distinct trains on lines 30, 29, 45, 50 representing A, 2A, 4A and 8A respectively. These trains are selectively applied singly and in combinations to trigger 20 through gates 51-54 controlled through the rectifier network shown by a potential applied to the terminal 1-9, corresponding to the required decimal-digitmultiplier, e.g. by cam- or relay-controlled contacts or by a trigger circuit (not shown). The potential may also be applied by recordcard-sensing brushes, and additional terminals 10, 11 may be added. Fig. 2 shows a device for multiplying by ten including a two-number adder as described in the parent Specification, and input lines 29, 30 which, owing to delay 25, apply the numbers A, 4A respectively (separated by delay t = “ p) to trigger 20. Since the output pulse train at S is delayed one digit period this train will represent 2(1 + 4)A = 10A. Simiilar more elaborate devices are described for multiplying by a hundred in one of which a two-number adder is employed and each digit period is divided into halves (the frequency of the timing pulses being doubled) during which (2<SP>4</SP> + 2<SP>5</SP>)A is formed and is added to 2A respectively: In a device for multiplying by a thousand (Fig. 5, not shown). employing, a subtractor as described in the parent Specification, the values (2<SP>9</SP>-2<SP>3</SP>)A and (2<SP>9</SP>-2<SP>3</SP>)A - 2<SP>2</SP>A = 500A respectively are formed during each half of a digit period. Alternatively such multiplication may be performed by the combination of an adder A.O, Fig. 6, subtractor S.O. and delay elements as indicated. Similarly arrangements are shown for multiplying by 10<SP>4</SP> to 10<SP>9</SP>.