This application note describes the basic issues that need to be addressed in order to implement digital signal processing systems using the PIC16C74 and provides application code modules and examples for DTMF tone generation, a 60 Hz notch filter, and a simple PID compensator for control systems. These routines can also be used with other PIC16C6X and PIC16C7XXX processors with minor modifications and the addition of external analog I/O devices.