This circuit is an asynchronous up and down counter. It is made asynchronous to lessen propagation delay. Applications of this counter are useful in microprocessor unit. Typically it is used in incrementing registers such as program counter and stack pointer.
Activating logic input at the top will make the counter to count up and activating logic input at the botton will make the counter to count down. We can only activate logic input one at a time. Enjoy.
