Question: It is desired to implement a PIC18F4321-based system as shown in Figure. The system will scan a hex keyboard with 16 keys, and drive three seven-segment displays. The PIC18F4321 will input each key pressed, scroll them in from the right side of the displays, and keep scrolling as each key is pressed. The leftmost digit is just discarded. The system continues indefinitely. Write a PIC18F assembly language program at address 0x100 to accomplish the above. Use ports and data memory addresses of your choice.
