requirements for a logic family is the ability to perform a logical operation fig4 depicts a circuit within the instant logic family which fulfills this requirement the circuit is basically the same circuit as the inversion circuit of fig3 except that there is an additional input b with its attendant input resistor therefore there are two inputs a and b each having their respective input resistors r1 and r2 the ground resistor has been designated r3 in this circuit as in the inversion circuit the resistance values of resistors r1 and r2 are much larger than the resistance value of ground resistor r3 this circuit operates in much the same manner as the inversion circuit of fig3 the main difference being that there are now two inputs and a logical operation is performed upon the inputs again during operation of this circuit the potential at clk is high if the input at either a or b is high or the input at both a and b are high ots1 does not switch therefore ots2 does not switch and the output is low however if the input at both a and b is low ots1 switches this causes the potential across ots2 to be high causing it to switch and pulling the output at out high therefore depending upon the nomenclature used this is either a nor gate or a nand gate that is if a low potential is a logical 34 0 34 and a high potential is a logical 34 1 34 then the circuit acts as a nor gate conversely if a low potential is a 34 1 34 and a high potential is a 34 0 34 then the circuit acts a nand gate a final example of a logic.