Patent GB-808752-A (GB)
Title: Magnetic core switching circuitry
IPC: G06F7/38
Filed: 1956-12-11
Abstract: 808,752. Digital electric calculating-apparatus. NATIONAL CASH REGISTER CO. Dec. 11, 1956 [Oct. 11, 1956], No. 37780/56. Class 106 (1). [Also in Group XXXIX] A binary adder comprises three registers E, F, K, Fig. 2, which utilize digit storage and control cores each of which has two remanent states respectively designated as true and false, the arrangement operating in such manner that the augend and addend are initially registered in the storage cores of the E and F registers respectively, the K register contains the carry digits during the addition process, and the total is contained in the E register with the carry digit, if any, registered in the K register, while the addend continues to be registered in register F. Initially all the cores are in the false state except for certain storage cores 1Es-4Es and 1Fs-4Fs in the E and F registers which are driven to the true state according to the binary one content of the augend and addend respectively. The E and F storage cores record 4-order binary numbers while the single K register storage core 1Ks records the carry digit. Each register includes control cores 1Ec-4Ec, 1Fc and 1Kc-3Kc. The register cores are associated with leads 35-37 which are energized by " half-current " pulses from control clocks 38, 40 and from a digit selector 39, the combination of two half-current pulses in the windings of any core being sufficient to reverse its remanent state. Primary energization is provided by a common pulse source 15, and the pulses are of the waveform and in the time positions, as shown in Fig. 4, such that a single storage core in each register such as lEs, 1Fs, is operated on in successive digit transfer cycles by the combination of pulses Cs, Cs and a single P1-P4 pulse train on leads 37, 35 and 36 respectively. The following operations are carried out in each digit transfer cycle which is divided up into the periods Rs, Wc, Rc, Ws:-(1) In the period Rs, the storage cores 1Es, 1Fs, pertaining to the first digit order and the carry digit storage core 1Ks are interrogated by driving them to the false remanent state, using negative pulses Cs, P1. If a one-digit registration is found, an output is induced in an associated sense winding 47, 48, 49 which passes to a transfer circuit 22, 23, 24. Each transfer circuit functions as a one-period delay and produces in the next period Wc an inhibiting output signal in windings 41, 43, 45 or windings 42, 44, 46 depending on whether the interrogated core was found to be false or true. (2) Certain control cores 1Ec-4Ec, 1Fc and 1Kc-3Kc are driven from false to true in the next period We by positive pulses Cc, P1, the remaining control cores being prevented from changing state by the combination of inhibiting signals from the transfer circuits. The output induced in the sense windings is not effective at this stage. (3) Negative pulses P1, Cc are applied to the control cores in the next period Rc and the cores are driven from true to false. Reversal of any control core in a register produces an output in the associated sense winding 47, 48, 49 which is effective over the transfer circuits in the next period Ws. (4) The final stage in the digit transfer cycle comprises the period Ws, during which period positive pulses Cs, P1 are applied to the storage cores 1Es, 1Fs, and 1Ks. These pulses in combination with inhibiting signals from the transfer circuits in windings 41-46, cause the storage core 1Es to assume a remanent state representing the first order sum of the digits initially stored in 1Es and 1Fs, cause core 1Fs to assume its initial remanent state, and register the carry digit, if any, as a true remanent state in core 1Ks. This operation is repeated in subsequent digit transfer cycles by applying the pulses Cc, Cs and P2 to the storage cores, and so on, until the addition operation is complete. The arrangement of the inhibiting windings and their mode of energization is such that core 1Es, for example, in the E register, will ultimately register a true condition if all the cores 1Es, 1Fs, and 1Ks are initially in the true state or if one only of any of them is true. The operation of the arrangement is discussed in the Specification on the basis of representing a logical proposition as a true or false setting of a storage core. The operation of the transfer circuits is controlled by signals Wc+Ws from a period signal generator 16 which occur in periods We and Ws and are applied by way of an OR gate 20. Each transfer circuit such as 22 comprises a trigger pair of transistors E1, Fig. 7, which is controlled in opposite respects by the signals Wc + Ws from the OR gate and by induced voltages in the associated sense winding 47, the sensing voltages being effective only during the periods Rc and Rs when a transistor amplifier 60 gated by Wc+Ws is able to conduct. The trigger pair outputs are applied over transistor amplifiers 71, 72 which invert the outputs and are also gated by Wc+Ws, and true and false inhibiting outputs are obtained in windings 42 and 41 respectively over transistor amplifiers 67 and 68. The transistor amplifiers and trigger pair are described in detail with reference to Figs. 9, 10, 10a, and 11 (not shown). It is stated that the addend in register F can be modified during operation so that the complement is stored in the register when all the digit transfer cycles are completed, this effect being obtained by connecting the inhibit windings on the F register storage cores 1Fs-4Fs to the false output of the transfer circuit 23 and the inhibit winding on the control core 1Fc to the true transfer circuit output.