Program Counter (PC)

It is a   16 bit  register.  It is a memory  pointer. It stores  the memory address  of the next  byte of the program to be executed. Memory  address is of 16  bits. Suppose a program  is stored in the memory  starting  from address 2000H ( 0010  000  0000  0000)  see fig  to execute this  program  starting  address is copied  in program counter (PC)  register. When the  program starts executing microprocessor provides  the memory  address from  program  counter.  The  first  statement  is accessed   at that location and is brought into the  microprocessor and  executed. While first statement . after executing  first  statement  microprocessor  get the  address of the  second  statement  from the program  counter.  Similarly  second statement  is also  executed  and program  counter is  incremented  by 1 and  points to the next  statement. The processor is repeated until   the program  is over.

Since  this register  points to the  memory  address of the program and keeps  incrementing by  one like a counter hence the name  given to it  is program counter.