The microprocessor is a small VLSI (very large scale integration) chip with many pins. It processes information and manage the exchange between the Input/Output units and main memory.
It is controlled by a sequence of instructions called microprocessor program, and the result of this program in sent to the appropriate periphiral (input and output).
The microprocessor consists of the following sections:
- Several registers which stores data.
- Arithmatic and logic unit (ALU)
- Control and timing unit.
Registers main function is storing data, some of them can be used by the programmer and some can not, and used only by the processor.
Most important registers:
- Accumulator: also known as A-register, is used for storing the results of mathematical operations.
- Instruction register: used to store the current instruction that are being executed in the microprocessor.
- Program counter: stores the address of the next instruction to be executed.
- Buffer register: stores data temporarily.
- Status register: stores the current state of the instruction that are being executed at the microprocessor.
- Stack pointer: points to (stores the location of) the place in the main memory called stack.
This unit executes the arithmetic and logical instructions.