3) Building ALU based 4-bit addition using two 74SL74 (4 D FF’s) and a 4-bit adder: • Build ‟a 4-bit Register out of D flip-flops. It should have the basic Clear pulse switch to clear the data and the Clock pulse switch input to give a clock pulse to the D flip-flop indicating the change of state. In this case, we have one input switch connected to input if each D flip-flop. All four outputs of the D flip-flops are connected to the 4 LEDs. For this online version: • Go to the Memory folder, and drag over 4 D Flip Flops. Label these flip-flops Bit 0, Bit 1,Bit 2,Bit 3. • Go to the Input/Output folder, and drag over one button. Label this clock, and connect it to each flip-flop. • Go to the Input/Output folder, and drag over one button. Label this Clear, and connect it to each flip-flop. • Go to the Wiring folder, and drag over four Pins. Connect these to the D of each D-Flip-Flop. Label these D0, D1, D2, and D3. • Go to the Input/Output folder, and drag over 4 LEDs and connect one to the Q of each flip flop.