Patent GB-673926-A (GB)
Title: Improvements in electrically operated calculating machines
Inventor: LARSEN FRIDTHIOF OSCAR VALDEMA
IPC: G06F3/027
Filed: 1947-10-14
Abstract: 673,926. Digital electric calculating-apparatus. AKTIEBOLAGET DUBA. Oct. 14, 1947, No. 27488/47. [A Specification was laid open to inspection under Sect. 91 of the Acts, Oct. 14, 1947.] Class 106 (i). A keyboard-controlled, electrically-operated calculating machine of the type comprising an input register (a) having a plurality of units (Va ... Vh) each settable by digit keys (d) to register one digit of a number to be entered, a plurality of selectors (Sa ... Sh), each set simultaneously with an associated input register unit (Va ... Vh) so as to select one of a plurality of pulse transmitters (I0 ... I9) arranged to transmit electric current pulses of different lengths to represent decimal digits and a sequence switch (STV) controlling the setting of column-shifting members (A ... H) for connecting the selected pulse transmitters (I0 ... I9) in the operating circuits of individually settable registering units (RR) forming a calculating register or accumulator (c), is provided with a multiplier register (M) having a plurality of registering units (IR ... IR3) each associated with a plurality of bank terminals (T<SP>1</SP>1, E<SP>1</SP> n , 1<SP>1</SP>, 01<SP>1</SP>) called "digit contacts" and a wiper (y ... y9) arranged to engage any one of the digit contacts, and means (MK, l6, A<SP>1</SP> ... D<SP>1</SP>) for connecting the pulse selectors (Sa ... Sh) and the pulse transmitters (10 ... 19) selected thereby in the operating circuits of the registering units of the multiplier register. The digit contacts have a common connection to, and are arranged to be separately connected in, the operating circuit of the setting relay (Im) of the pulse transmitters by means of the wipers (y ... y9), each of which alternately closes and interrupts the operating circuit as it is swept towards its home position, causing the pulse transmitters to operate and enter in the accumulator (c) the factor recorded in the input register (a) a number of times corresponding to the value of the digit in the registering unit (IR ... IR3) in question. When the wiper reaches its home position it closes a separate operating circuit of the column-shifting members to cause an advance of one step. The key contacts 1 ... 9, 0 (d), Fig. 1, are connected to the group of contacts in each input register bank SVa ... SVh, and also, through a wire e, to a relay ST controlling the stepping switch STV. In this way, operating relays SV1 ... SV8 are energized in succession as the digit keys are depressed. In each case the corresponding switch Va ... Vh hunts for the contact which is connected to the key depressed and when a circuit is established for a relay IN, the operating relay SV1 ... SV8 is de-ener. gized. A second series of switches Sa ... Sh move synchronously with the switches Va ... Vh, selecting pulse transmitters I0 ... I9 corresponding with the digit value represented. The wipers Sa ... Sh are electrically connected to the wipers of a series of column-shifting switches A ... H which have a common driving- shaft stepped on each time a digit is entered until disabled by a relay DM energized by depressing a key DR when the decimal point is reached. In this way pulse transmitters corresponding with the digit value to be entered are connected to the appropriate coupling magnets RR in the accumulator, and when a termination key TS is depressed a relay Im is energized to cause rotation of a shaft Ia carrying the pulse transmitters, the outputs from which cause registering discs to be coupled to a rotating shaft for differential periods (Fig. 4, not shown). Addition is performed by repeated entries. Multiplication is performed by entering the first factor (multiplier) as described above, and then depressing a key MKT to energize a relay MK which changes over contacts mk to connect with lines l6 and a further set of column-shifting members A<SP>1</SP> .. D<SP>1</SP>. Upon depression of the key TS, the pulse transmitters operate to set up the multiplier by energization of coupling magnets IR ... IR3. The second factor (multiplicand) is entered in the register a and a key MT is depressed, energizing a relay MR which changes over contacts whereby, when the key TS is depressed a further relay Mar establishes a connection from a pulse transmitter Ix to send pulses equal to the number of decimal places in the multiplier to step on the columnshift devices A ... H, thus providing for correct positioning of the decimal point in the final product. Upon release of the key TS, impulses are passed to the impulse transmitter control magnet Im via the wiper of the lowest multiplier digit repeatedly to cause the multiplicand to be added into the accumulator as the wiper steps home. When homed, a further column-shift impulse is sent and then the next higher multiplier digit controls the repeated addition in a similar manner. Division is carried out in known manner by repeated subtraction. Provision for decimal point adjustment is described. The result of a calculation may be transferred from the accumulator c to indicating, printing, or punching devices or to a grand total register which may be common to a plurality of accumulators (Fig. 4, not shown). A number of keyboards may be used to operate a single calculator, in which case a finder switch RG may be arranged between the input register and the keyboards. The use of photo-cells in connection with the accumulator is also suggested.