A JK flip$-$flop receives a clock and two inputs, J and K$.$ On the rising edge of the clock, it updates the output, Q$.$ If J and K are both $0,$ Q retains its old value. If only J is $1,$Q becomes $1.$ If only K is $1,$Q becomes $0.$ If both J and K are $1,$ Q becomes the opposite of its present state.