A register is a group of 1- bit memory cells. To make a N-bit register we need N 1-bit memory cells.
Register with parallel load: We can represent a simple 4-bit register as: We can give the values to be stored at input and we get that value stored at the next clock pulse.
But in this circuit we have to maintain the inputs to keep the outputs unchanged as we don’t have the input condition in D Flip-flop for unchanged output. Hence we modify the above circuit with an extra
input LOAD which when ‘1’ would mean there is a new input data to be stored and LOAD=0 would mean we have keep the stored data same. The modified circuit is as: