ABSTRACT
The microprocessor is a central processing unit (CPU) on a single chip, and contains all the necessary features which allow it to fetch instructions from memory, decode the instructions, and execute them in a sequential fashion. A basic element within the CPU and other components within the system is the register. A register is similar to a memory location in that data can be written to and read from the register by the microprocessor. Physically, an interrupt takes the form of a single input signal to the CPU which, when active, causes the CPU to start executing a program from a predefined address. The interrupt will cause the CPU to transfer program control to its interrupt service routine which, like the subroutine, must have a return address to the main program stored on the stack. The interrupts considered so far are the general purpose interrupts to the CPU which can normally be enabled and disabled by the CPU.
