The program counter keeps track of program execution. To execute a program the starting address of the program is loaded in program. The PC sends out an address to fetch a byte of instruction from memory and increments its content automatically.
A device which contains the microprocessor with integrated peripherals like memory, serial ports, parallel ports, timer/counter, interrupt controller, data acquisition interfaces like ADC,DAC is called micro controller.
The features are • single supply +5 volt operation using HMOS technology. • 4096 bytes program memory on chip (not on 8031) • 128 data memory on chip. • Four register banks. • Two multiple mode, 16-bit timer/counter. • Extensive Boolean processing capabilities. • 64 KB external RAM size • 32 bidirectional individually addressable I/O lines. • 8 bit CPU optimized for control applications.