Fusible link matrix for programmable networks

Claim 1

In combination: a threshold logic circuit having an electrically adjustable threshold reference level, said threshold logic circuit including an input summation network and a voltage source from which input signals to said summing network are derived, said threshold logic circuit also including a voltage divider connected across said source for establishing a predetermined threshold reference level having a constant proportionality relationship with respect to the summation result of said summation network with variations in the voltage level of said source, said voltage divider including a plurality of resistors and a plurality of electrically actuable fusible links interconnected so that the characteristics of said voltage divider and thus the value of said threshold reference level are dependent upon the number of fusible links which are actuated, said threshold logic circuit further including comparing means for comparing the summation result of said summation network with said threshold reference level and providing an output indication responsive thereto, and selective addressing means coupled to said fusible links so as to permit selectively applying actuating current thereto, said selective addressing means including a first addressing bus commonly coupled to one end of all of said fusible links and a plurality of additional addressing busses respectively coupled to the other ends of said fusible links so that actuation of a fusible link is obtained by energizing said first addressing bus and the respective one of said additional addressing busses corresponding thereto, said selective addressing means also including a plurality of decoupling diodes connected so that an actuating current is applicable to each fusible link only through at least one of said diodes.