Improvements in or relating to calculating machines

Abstract

Abstract 600,896. Electrical calculating-apparatus. BRITISH TABULATING MACHINE CO., Ltd. Jan. 30, 1946, No. 3042. Convention date, Feb. 8, 1945. [Class 106 (i)] Electrical calculating apparatus for determining the value of a power series automatically, comprises a value source in which the coefficients of a plurality of terms of the series are stored, means for reading selected coefficients from the value source successively into the register of an arithmetical computing apparatus, means for setting up the argument in another register of the said computing apparatus and means for successively combining the selected coefficients with the argument to produce a total which equals the total of the selected terms of the power series. The apparatus is controlled by a programme tape and is able to add, subtract, multiply, divide, compute power series, logarithmic series, Taylor's series, square roots, logarithms, exponentials, trigonometric functions and inverse trigonometric functions, and other functions based on these operations. The machine has several rows of dial switches D, Fig. 1, and several storage registers, most of which have a 24-column capacity while a product-quotient register PQ, Fig. 25g, has 47 orders. In all storage registers, the highest order is used to determine the sign of the number, so that computation can be effected on a 23-digit number, any product having up to 46 digits. Additionally, there are a few registers having only one or two orders used as sequence registers or calculation step counters. The coefficients of the power series may be stored in code form on a value tape which can be selected according to the nature of the series and the range of the variable, or they may be obtained from the energization of relays which close selected contacts in a complex network. Drive mechanism. A motor drives several shafts carrying a large number of cams which open and close contacts at predetermined times in each machine cycle (Figs. 20a, b, c, not shown). Register structure. All the registers in the machine have the same general structure, as described in Specification 483,021, and rotate when clutched to the motor drive by a clutch lever controlled by an advance magnet AM, being declutched at the energization of a stop magnet SPM (Figs. 12-16, not shown). The clutch lever may be rocked to declutching position by either of two knock-off pins, operative normally at cycle points " 0 " and " 13 " in each cycle, although they may be timed early or late in some of the sequence operation registers. Each register has one or more known electrical readouts for each order. When an order passes from 9 to 0, contacts are closed to prepare carry to the next order in a carry-over cycle. Record tape handling and sensing means. The apparatus is controlled by the perforations in a programme tape, Fig. 19, which is fed forward step-by-step so that the perforations can be sensed, one line at a time. The machine also has three value tape stations, Fig. 1, one of which may be operative at any time to select a portion of the value tape bearing perforations representing coefficients of terms in a power series to be evaluated. The value tape, Fig. 17, may be fed forwards or backwards one step at a time, four lines of perforations arranged in a code, Fig. 18, being sensed at one time. The tape drive, forward or reverse, as the case may be, occurs when a clutch magnet 82 (forward) or 82r (reverse) is energized to actuate pawl- and-ratchet mechanism (Figs. 3-9, not shown). Code for programme tape. The programme tape, Fig. 19, is divided into 24 columns, perforations in the first eight selecting a source from which a value is to read out for use in a computation, the second eight select the means into which a value is to be entered and the type of calculation to be performed, while the last eight columns are used to control miscellaneous functions of the machine. The tape is sensed one row at a time by a row of pins 150P, the presence of a hole in any column in the " Out," " In " and " Miscellaneous " fields energizing a corresponding relay A1-8, B1-8, C1-8. The A, B and C relays, Fig. 22a (and Figs. 22b, 22c, not shown) close contacts to establish circuit paths to different posts a1-256, b1-256, c1-256, from which the code control is passed to different points of the machine to control its functions. Dial switches. Numbers, on which calculations are to be performed, may be entered in any of 60 rows of dial switches, twenty-four denominational switches to each row, Fig. 23. The contact arm of each switch D is connected to an " out " relay contact 1D " out " 1-24... 60D " out " 1-24 controlled by relays 1D " out "-60D " out," whereby values may be read out of a selected row of switches. The corresponding digit contacts in all the switches are connected to corresponding digit lines 192-0 to 192-9 connected to the central blades of invert relay contacts D " inv." 0-9. When the relay D " inv." energizes, it shifts the central blades to connect the nine-complementarily related contacts, to read out the ninescomplement of the number set up on the operative row of switches. The contacts are connected to the usual cam contacts SC1-9 closing briefly at cycle points 1-9 to send out digit impulses through bus-bars B1-B24 to a selected valuereceiving means. The relays 1D " out " 60D " out " are controlled by the " out " field of the programme tape through the A network shown in Fig. 22a. The relay D " inv. " is energized through the C network when the " Miscellaneous " field is perforated 21. Storage registers. The machine, as described, has 72 storage registers. Parts of registers 1 and 3 are shown in Fig. 24b. The advance magnets AM of each order are connected at the energization of the corresponding relay 1S " in " -72S "in " to the bus-bars B1-24 to receive timed digital impulses from the selected reading- out means. The registers have read-outs 1SRO-72SRO connected at the energization of the corresponding relay 1S " out "-72S " out to the bus-bars to send out timed. digital impulses. The registers are selected for receiving or reading-out under control of the '' in " and " out " fields of the programme tape. The complement of the number in a storage register is read out when a relay S " inv." (not shown) is energized, Carry operations. Carry is effected in known manner, but because of the attenuation of the carry inpulse in the event of successive carry through several orders, carry from the 12th and 24th orders is boosted by special quick-acting relays TB. Advance of the registers more than one step at carry is prevented by the second knock-off pin, already referred to but not shown, which acts at time '' 13." Resetting storage register. To reset a register, the register code is punched in both the in and out fields of the programme tape to operate the related S " in " and S " out " relays (Fig. 24a, not shown) to establish a circuit at time " 14," when contacts SC16 close, to energize a coil S " res " which holds till time " 0 " in the next cycle, during which time the selected register is reset by addition of the tens complement in each order, the carry control relays being held inoperative. Multiplying and dividing section. Multiplication and division may be initiated under control of the programme tape or may occur as part of a larger operation. The operations are broadly as described in Specifications 456,367 and 497,039, but include certain additional features. A single order multiplying-dividing step register MDS, Figs. 25l, 25n, controls a column shift network and has five read-outs A-E, and is advanced only one step at a time. The dividend register DD has 45 orders while the product and quotient register PQ has 47 orders, the 47th order determining the sign and controlling direct or complemental reading-out. A register QS (not shown) evaluates the shift back of the quotient in the register PQ and has two orders connected to two dial switches DQ (not shown) set to 22-N where N is the number of operating decimal places in the quotient. Multiplication. Operation. The first line of the programme tape is sensed to select the switch row D, Fig. 1, 23, or storage register from which the multiplicand is to be read, inversion taking place if the highest order, by standing at 9, indicates a negative number. In the next cycle, timed impulses representative of the number being read out are impressed on the bus-bars B1-B24, and due to the energization of a relay I "in," the digit impulses are applied to the advance magnets AM of an intermediate register I (Fig. 25a, not shown). A relay DD-PQ " res " resets the registers PQ, DD, QS. A series of well-known steps ensues to read out the multiplicand from the register I into the build-up registers ML1-9, in which multiples of the multiplicand are built up (Figs. 25b-e, not shown). During this process, the register I is reset and the second line of the programme tape is sensed to read the multiplier from its source into the register I, and from the register I into a multiplier receiving register MP, Fig. 25f, and for each order of MP which receives a significant digit, the corresponding relay MPH energizes. The energized relays MPH operate related contacts in a column shift relay network, Fig. 25l, the network being divided into sections corresponding to the odd and even orders. Circuit is established to the lowermost column shift relays CS on the odd and even sides, the energized CS relays and the corresponding orders of the register MP coacting to energize selectively corresponding multiplication relays IX- 9X and 1XX-9XX, Fig. 25n, according to the digits standing in the lowest odd and even orders of the register MP. The energized X and XX relays select the multiples to be read out of the ML registers (Fig. 25b, not shown) simultaneously into registers PQ and DD, respectively, by closing related sets of contacts, e.g. 1X1-24, Fig. 25h (and Figs.

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