Patent GB-654368-A (GB)
Title: Improvements in or relating to electrical calculating apparatus
IPC: G06F7/44
Filed: 1947-08-01
Abstract: 654,368. Calculating-apparatus. WESTERN ELECTRIC CO., Inc. Aug. 1, 1947, No. 20984. Convention date, Sept. 29, 1945. [Class 106 (i)] Electrical calculating apparatus comprises a summing device having a plurality of decimal denominational orders, each order consisting of three registers each comprising a set of relays adapted to express a digit in code and also to express the nine's complement of said digit in the same code, the codes used in each of said registers being the same, and each set of relays being divided into a plurality of sub-groups each having a number of relays equal to a factor of the base of the calculation. Multiplication is effected by repeated addition and the three registers correspond to the three factors of a simple addition sum, viz., "augend," "addend" and " sum." The machine as illustrated can effect the multiplication of a two-digit multiplicand by a two - digit multiplier, both of which are entered by respective keys in a keyboard, Fig. 1A. In the " biquinary " code used in the present machine, any digit 0-9 is represented by energization of one relay in a group of two weighted 0 and 5 respectively and one relay in a group of five weighted 0, 1, 2, 3 and 4. In each register five denominational orders of relays are provided and each order in which a representation may occur includes seven computing relays. In the present case all five orders of relays B and C which alternately act as " augend " and " sum " have seven computing relays split into two groups of two (binary) and five (quinary) and denoted B00 ; B10-B1; B2; B3 ; B4; B5 ; and C00; C10- C1 ; C2 ; C3 ; C4 ; C5 respectively, but only two orders of relays A which represent the addend are provided with seven relays also split into two groups of two and five and denoted A00 ; A10-A1 ; A2 ; A3; A4; A5. To reduce the number of additions to be made where possible,. the following " shortcut " method is employed. If the two digits of the multiplier are both less than 5 (e.g. 34), the multiplication is effected by repeated additions of the multiplicand a number of times equal to the sum of the two digits (e.g. in this case 3+4=7) and the necessary denominational shift is effected after the third addition. If, however, one of the digits of the multiplier is greater than 5, e.g. 28, i.e. 3 tens-2 units, the number of additions is 2+3, i.e. 5, and when the denominational shift is effected after two additions, the sum is expressed as the " tens complement " before the last three additions are effected. If both of the digits are greater than 5, e.g. 88, i.e. 1 hundreds-1 tens-2 units, the number of repeated additions of the multiplicand is 1+1+2, i.e. 4, and a denominational shift is effected after the second and third additions and an inversion, i.e. expressing a sum as its " tens complement " takes place after the third addition. The number of additions is therefore determined by the multiplier keys, Fig. 1A, and the pattern of operations, i.e. the number of additions, the denominational shifts and the inversions, is controlled by three groups of relays 7, 8 and 10. The multiplicand keys 1 and 2 directly operate the addend relays in rectangles 3 and 4. The multiplier keys 5 and 6 control the two sets of counting relays 7 and 8 which are connected to the power control circuit containing three gas valves LB ; OP ; LC, the function of which will be explained later, and from which impulses are sent via the counting relay control relays 10, which are energized in accordance with the setting of the multiplier keys, via the channels 12, 13, 14, 15 and 16 via switching relays to the five decimal denominational orders of computing relays B and C from whence the impulses pass to product display lamps 20. In each decimal denomination the following occurs : Incoming carry + Augend + Addend = Outgoing carry + Sum and the Sum is expressed by operation of a binary relay and a quinary relay of either of groups B and C. The basis on which each denominational network is built is shown in Fig. 2 from which it can be seen that the impulse path to the seven relays C from the " carry 0 " or " carry 1 " lead and the outgoing carry path to the next higher denomination are determined by contacts controlled by the relays A and B. As was made apparent above the shortcut method employed sometimes necessitates the inversion, i.e. the expression of a sum as the tens complement, of a sum obtained from one of the repeated additions and for this purpose each denominational order network contains sign relays designated by a P or an N, see Fig. 7, which through associated contacts (designated BP, CP, BN, CN) determine if the relays B or C are to be set to represent the true sum of one of the additions or the tens complement thereof. Moreover, due to the fact that the relays B and C operate alternately for expression of the sum in successive additions, each network must contain contacts operated by relays designated BA; BR; CA; CR, which control contacts to determine, by controlling the path through the network, which of the relays B or C are to represent the sum at a particular stage. To effect the denominational shift after a series of additions determined by one multiplier digit, each decimal denominational order network contains relays designated BS and CS which operate associated contacts also designated BS and CS to change the path through each denominational network back to the sum computing relays B or C of the preceding denominational order. Each order also includes relays designated BZ, CZ which operate associated contacts positioned in such a way that at any addition stage at which they are operated the representation on the relays B or C then acting as " the augend " is transferred to the relays C or B acting as " the sum " regardless of the addend representation on relays A. In view of the alternative functions of relays B and C in successive addition stages, each decimal denominational network must have four incoming and outgoing carry leads instead of two as in basic network of Fig. 2. One complete decimal denominational order network of the above relays, leads and associated contacts is shown in Fig. 14. Summing-cycle control. The power control valves OP, LB, LC and an additional valve EX are interconnected as shown in Fig. 9 and operation is as follows. Keys are set to represent multiplier and multiplicand respectively. Depression of a start key 912 energizes a start relay 913, whereupon valve OP fires to cause C computing relays to be set to represent original " augend " of " 00000," sum relays B operate in accordance with the representation on the addend relays A, locking valve LB fires to hold the operated relays B operated, whereupon operating valve OP is extinguished. The operated relays C are then released and a new circuit for the operating tube OP is established and the operation continues as before with relays B and C alternately changing functions. It can be seen therefore that the relays establish firing circuits for the valves OP, LB and LC which in turn operate the relays in new combinations. The four relays 901, 902, 903, 904 represent the relays denoted to their left in Fig. 9 and the circuits controlled thereby are series circuits under the joint control of all the associated relays. Valves LB and LC mutually control each other and the additional valve EX ensures that the valve OP is extinguished at the appropriate times. Fig. 10 represents the summing operations and shows the sequence of operations of the counting relays to determine the number of repeated additions to be performed when the multiplier keys 5, Fig. 1A, have been set to the value 23. The graphs 1004, 1005, 1006 respectively represent the periods of operation of the tubes LB, OP and LC. The operation is as follows: upon depression of the start key ST1, valves OP and LB fire. The anode of valve OP is connected through a contact of the units key " 3 " to the counting relay CC3, valve LC fires extinguishing the valves OP and LB and the counting relay CC3 now closes a circuit through the relay BRC to the counting relay BC2 which is rendered effective upon the next firing of the valve OP. Valve LB then fires to extinguish the valves OP and LC, relay BC2 closes a circuit through a contact 1013 of relay CRC to counting relay CC1 which operates to connect a circuit through relay GTC and BC2 is the next operated counting relay as determined by the tens multiplier key T-2, Fig. 1A. Each decimal denominal order of computing relays B and C, switch relays BR, BS, CR, CS, BP, BN, CP, CN, BA, CA control a plurality of contacts connected in circuits (Figs. 22, 23, 24 and 25, not shown), with contacts of the counting relays 7 and 8, with starting and release relays and with the valves OP, LB and LC. These circuits form extensive check circuits by which each addition stage is checked and the arrangement is such that an alarm circuit is operated if a check circuit fails to close. The following is an example of a multiplication effected by the apparatus 37 x 23=851 :- The multiplicand keys T-3 and U-7 and the multiplier keys T-2 and U-3 are set. The four appropriate addend relays A and the appropriate counting relays are set. Momentary depression of the start key results in setting of the five decimal denominational orders of C computing relays to represent " 00000," the appropriate counting relays and counting control relays now operate in correct sequence as determined by the depressed multiplier keys and as controlled the valves LB, OP and LC, the power arrangements of which are shown in Fig. 26. It can be seen therefore that the result is thus calculated denomination by denomination and the result " 00851 " is indicated by the product display lamps 20, Fig. 1A. This condition becomes stable and will persist until released by the operator by operation of a release key.