Patent GB-525330-A (GB)
Title: Improvements in or relating to electrically operated calculating apparatus
IPC: G06F7/46
Filed: 1938-11-21
Abstract: 525,330. Calculating-apparatus. STANDARD TELEPHONES & CABLES, Ltd. (Kozma, L., and Kruithof, J.). Nov. 21, 1938, No. 30530. [Class 106 (i)] . An electrical calculating apparatus formed as a unit or adapted for control by a number of operators, comprises a control unit including a printer, means in said control unit for submitting a problem to the calculating unit, means for causing the printer to print said problem concurrently with its submission, means in said calculator for ascertaining the solution to said problem and means for causing said printer to print the result. Each control unit or operator's equipment comprises a single bank of numeral keys and control keys for signalling the kind of calculation and the decimal point. A key marked "equals" is provided for signalling the termination of the transmission of a problem and a key marked "cancel" is provided for use in the correction of errors. A printing device for recording the data, the characteristic signs and the result is also provided. The 'operator's equipment is connected to the calculating equipment by a line and access circuit arrangement with a sequence switch as described in Specification 525,329. The calculating equipment is constituted by sets of telephone-type contact making relays, eleven point step-by-step switches. power driven impulse sequence switches and impulse distributers. A complete calculating unit is shown in Fig. 1 diagrammatically. The operator's set, Fig. 2, is connected to a line and access circuit, Fig. 3, and thence through a code receiving set, Fig. 4, with transferring and storage relays to one of a number of calculating circuits, Fig. 5, with sequence switches for carrying out the different calculations. The calculating sets are connected by distributer circuits, Fig. 6, to route impulses created by the calculating circuits to the solution circuits, Fig. 7. The solution circuits are connected to a circuit, Fig. 8, which sends out the result of the calculation to the operator's printing device. Operation. The operator depresses the start, key and if a calculating set is idle he receives a send signal and then depresses the digit keys for the first number. The first or highest digit is sent to a set of receiving relays and is then transmitted to the first set of denominational groups of storage relays whereupon the receiving relays are returned to normal ready to receive the next digit. After the units digit is sent the operator sends the decimal signal. The operation of the storage relays connects up code sending relays to transmit a code signal to the operator which is signalled back to the calculating equipment and initiates the printing of the digits of the number at the operator's station. If the number is not correctly transmitted the ''cancel" key is depressed to restore the calculating equipment to normal. If the number is correct the sign for the kind of calculation is then transmitted whereupon the distributer and sequence switches are operated to effect the transmission of the digits from the storage relays to the calculating equipment. The second number has, in the meantime, been received, checked and printed and is then transmitted to the calculating equipment. When the final number has been sent the operator depresses the "equals" key and the result is then computed the digits being signalled to the operator and back to the calculating equipment which thereupon sends a printing signal and the result is recorded. The apparatus is restored to normal and a new availability sign is sent to the operator. Subtraction is effected by adding the complement, with respect to 9, of the number to be subtracted and by adding unity to the last digit in the result. Relays co-operating with the eleven point switches enable the transfer operations to be effected. Multiplication is performed by setting the two factors on the storage relays, the multiplication sign being sent before the second factor. The distributer circuits are modified by operation of the sign key and four sequence switches are provided for the code numbers 1, 2, 4 and 5 to effect transmission of the corresponding multiples under control of the multiplier storage relays. Division is effected in the usual manner by repeated subtraction and correction. Comparison of the divisor with the part of the dividend under consideration is effected by use of potentiometric apparatus and relays. The electrical circuit arrangements and apparatus for multiplication and division are the same as those described in Specification 525,398. Digit counting switches are employed to count the digits for the purpose of determining the position of the decimal point in the case of multiplication and division: this mechanism forms the subject-matter of Specification 525,396. In the apparatus described the impulse sender sequence switches, distributer circuit and calculating equipment are duplicated and identical to those set forth in Specification 525,397. The calculation is performed simultaneously by both sets and compared by a test relay, an alarm or signal being given if the results do not agree. In a modification step by step switches are employed instead of the power driven sequence switches. In this form for multiplication the impulses sent to the solution storage switches represent the units and tens of the partial products.