Patent GB-581565-A (GB)
Title: Improvements in or relating to electrically operated calculating equipment
IPC: G06F7/40
Filed: 1941-05-02
Abstract: 581,565. Calculating - apparatus. STANDARD TELEPHONES & CABLES, Ltd., HARTLEY, G. C., and REYNOLDS, W. J. May 2, 1941, No. 5716. [Class 106(i)] Electrically-operated apparatus for automatically determining a desired function of a number comprises two translator circuits, means for entering a number as the sum of two numbers, the second of which is small compared to the first, means for entering the first number into both translator circuits, means for multiplying the result obtained from the second translator circuit by the said second number, and means for adding the product to the result obtained from the first translator circuits. The invention is described as applied to obtaining the trigonornotrical functions sine and cosine of an angle B, the angle being considered as made up of the angles #‹+d#. Approximating by Taylor's Theorem the following obtains Sin #=Sin #‹+d#Cos #‹ and Cos #=Cos #‹ - d#Sin #‹ The circuits are arranged to carry out the calculations in the binary scale or radix two. the manner in which an angle is expressed in radix two is described in Specification 571,687, [Group XXXVIII], and an angle so entered may be stored in a set of relays Q-Z, Fig. 2, each representing a digit of the number. The relays are divided into groups to represent the angles #‹ and d#. The left-hand group of relays Q-V has the contacts of the relays arranged as shown in Fig. 3, in the circuits of relays A-H, and of eight wires 000-111 whereby any one of the six-figure number relays 000,000-111,111 may be selected. There are sixty-four of these relays, only a few are shown in Fig. 3. The selected relay has its contacts connected to appropriate terminals of a set of terminals AT, Fig. 4, and crossconnected to a set of terminals ST in circuit with the windings of relays AA-LL. The cross-connections are so arranged that the relays represent the twelve' different digits of a number which expresses in radix two the value of the function Sin #‹ or Cos #‹. The relays AA-LL are associated with terminals a-l in a storage group or other calculating circuit. The right-hand group of relays W-Z, Fig. 2, are connected in a similar manner to that described above to represent the value d#. The complete circuit arrangement for determining the value Sin # is shown diagrammatically in Fig. 5. The blocks on the left represent the relays Q-V and W-Z, Fig. 2 ; the contacts of these relays operate in circuits TS and RS as described with reference to Fig. 3; TRS, TRC and TRR are circuit arrangements corresponding to Fig. 4 for obtaining the values Sin #‹, Cos #‹ and d# respectively. The product of the values from TRC and TRR is obtained in a circuit arrangement MU similar to that described in Specification 578,041 and the result added to the value from TRS in a circuit arrangement AS similar to that described in Specification 577,893. The apparatus may be employed in the determination of the position of an aeroplane from the observations of the range, angle of elevation and bearing. The process of division may be performed by the circuit arrangements described. The dividend and divisor are entered, the reciprocal of the divisor is obtained in accordance with the invention and the quotient determined by multiplication as described in Specification 578,041.