Browse Prior Art Database

Exclusive Or Latch

IP.com Disclosure Number: IPCOM000094887D
Original Publication Date: 1965-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

VonFeldt, JL: AUTHOR

Abstract

The latch in drawing A includes silicon-controlled rectifier 1 with input terminal 7 coupled to the control electrode of 1 by way of diode 2 and to the cathode by way of diode 3. Input terminal 8 is connected to the cathode by way of diode 4. Diodes 3 and 4 form a positive And. The anode of rectifier 1 is connected to the base of output transistor 5.

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Exclusive Or Latch

The latch in drawing A includes silicon-controlled rectifier 1 with input terminal 7 coupled to the control electrode of 1 by way of diode 2 and to the cathode by way of diode 3. Input terminal 8 is connected to the cathode by way of diode 4. Diodes 3 and 4 form a positive And. The anode of rectifier 1 is connected to the base of output transistor 5.

The operation of the latch is indicated by the sequential truth table of drawing
B. Inputs 7 and 8 are in the 0 states when ground potential is applied and in the 1 states when positive three-volt signals are applied. Output Z is in the 0 state and the 1 state when rectifier 1 is nonconducting and conducting, respectively.

The six stable states are enclosed in circles. Unstable states 3 and 4 are not circled. If rectifier 1 is nonconducting, inputs 7 and 8 must be driven to the 1 and 0 conditions to switch the rectifier on. If the rectifier is cut off, inputs 7 and 8 must be both driven to the 1 state to turn the rectifier off. When input 7 is at the 0 state, Z cannot change state. When input 7 is at the 1 state, Z is the complement of input 8.

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