| 摘要 |
1,035,570. Sensing circuits for magnetic core matrices; tunnel diode pulse circuits. INTERNATIONAL BUSINESS MACHINES CORPORATION. Dec. 7, 1964 [Dec. 31, 1963], No. 49615/64. Headings H3B and H3T. The output from a magnetic thin film memory matrix is passed to a sensing circuit including an amplifier 50, transmission line 52, and tunnel diodes 60, 62. During read-out from the matrix the tunnel diodes are both gated so that they operate in the low positive resistance regions of their characteristics, just below the peak. A positive output pulse reaching 57 causes diode 60 to switch to the high positive resistance region, the voltage rise at 68 providing a data output signal. In addition, resistors 56, 58 bias diode 62 away from its characteristic peak to prevent a subsequent negative pulse causing it to switch. Similarly, a negative output pulse reaching 57 produces an output signal at 70. The transmission line 52 has an effective length (e.g. 6 nanoseconds) less than that of the output pulse (e.g. 8 nanoseconds), so that the trailing edge of the pulse is attenuated. During a subsequent write operation the spurious pulse induced in the sense line does not switch diodes 60, 62 since they are not gated. Furthermore, after the delay time of line 52 the reflected wave substantially attenuates the spurious pulse. The impedance across terminals 51, 53 is matched to the characteristic impedance of the line. In a modified circuit, Fig. 5, auxiliary tunnel diodes 80, 82 quantize the pulses reaching diodes 60, 62. When the diodes are gated, a positive pulse at 79 switches diode 80 and the voltage across diode 60 changes by a predetermined amount to switch diode 60. Reference has been directed by the Comptroller to Specification 986,677. |
