Patent GB-877171-A (GB)
Title: Improvements in or relating to electronic binary adders
IPC: G06F7/38
Filed: 1958-07-11
Abstract: 877,171. Parametrically-excited resonators. INTERNATIONAL BUSINESS MACHINES CORPORATION. July 1, 1958 [July 15, 1957], No. 22291/58. Addition to 793,799. Class 40 (9). [Also in Group XIX] In a series resonant circuit L, C, Fig. 1B, in which one reactance is non-linear and the circuit is biased by a D.C. potential, parametric excitation is effected by a power supply comprising a 1 mc/s. sine-wave voltage amplitude-modulated with a 1 kc/s. square-wave voltage, and a sub-harmonic output voltage of 0.5 mc/s. is developed across L and C during those periods when the amplitude-modulated power supply voltage exceeds a finite critical value. As described in the parent Specification, the phase of the sub-harmonic has one of two possible values # or # which is determined by a subharmonic control voltage of the same frequency applied in conjunction with the power supply, the sub-harmonic output, once established, being able to continue with its initial phase relationship after the control voltage is terminated. The two possible phases # and # of the subharmonic output represent the binary digits 0 and 1 respectively. The resonator derives its power and control voltages from a thermionic valve circuit, Figs. 1A and 2A to 2E (not shown), comprising amplifying, waveshaping and modulating stages, the phase of the control voltage being determined by a multivibrator and change-over switch. In this circuit the control and power voltages are combined in a mixing stage for application in series with the resonant circuit. The final stage amplifier (not shown) and the resonant circuit may be connected with an oscilloscope by way of a 4-position switch for determination of the the amplifier output and the current and charge variation in the resonant circuit. A parametrically excited resonator as described is represented in the remaining figures by the block diagram in Fig. 4, the sub-harmonic controlling input and the fundamental power input being shown as separate figures. Fig. 5 denotes a sub-harmonic phase inverter for converting a # to a #o signal or vice versa, the inverter being constituted by an electronic amplifier or a halfwave length of coaxial cable, transmission line or waveguide. Majority circuit. A resonator may be controlled by three sub-harmonic inputs A, B, C, Fig. 6, each having the same amplitude and a characterizing phase position of # or #o. The sub-harmonic output phase is then determined by the phase of the majority of the inputs. OR circuit. In the arrangement shown in Fig. 7, two sub-harmonic inputs A, B are combined with a reference sub-harmonic input M having a constant phase position of #. A# output is then obtained if either or both the inputs A, B are of the same phase. AND circuit. This arrangement, Fig. 8, is the same as the OR circuit except that the reference sub-harmonic has its phase inverted to #o. Both inputs A, B must then have the phase # for this phase output to be obtained. Binary adder. Binary signals An, Bn, Cn, Fig. 9, each characterized by a phase position # or #0 and of sub-harmonic frequency are applied to a combination of resonators 100- 105 arranged in three stages and operating as Majority, OR or AND circuits as shown. The power supply P 1  of fundamental frequency is connected to each stage in turn with overlapping change-over periods by switches S11-S13, the carry output being derived from the majority resonator circuit in the first stage while the sum output is obtained from the OR circuit in the final stage. The AND and OR circuits are connected to a common reference input M of phase #, the three-input OR circuit 101 having its reference phase voltage doubled by the provision of a series resistance R/2 of lowered value. Alternative binary adder. As shown in Fig. 10, the adder comprises a majority resonator circuit 201 and an AND-OR circuit 202 energized successively by the fundamental power supply P 1  over switches S11 and S12. As in the previous adder, the carry output is obtained from the majority circuit. This output is also inverted at 201A and is combined with the binary inputs An, Bn, Cn, the amplitude of the inverted signal being of twice the value of the other inputs to the resonator circuit 202 so that the circuit performs the logical AND-OR function.