The 7447 chip is used to drive 7 segment display. You must use the 7447 with a common anode 7-segment display. The input to the 7447 is a binary number DCBA where D is 8s, C is 4s, B is 2s and A is 1s. The inputs DCBA often come from a binary counter. Output Pin Diagram This pin diagram of 7447 IC where Pin 7 - A Pin 1 - B Pin 2 - C Pin 6 - D In Seven Segment Display (Common Cathode) Pins are represented by alphabets on display as well as on 7447 ic For more details have look at circuit diagram below Circuit Diagram This is whole working circuit for seven segment display R0 - 390 ohms (Led with dip switch resistance ) R1 - 100 ohms R2 - 1k ohms