Microprocessor

 The CPU of Microcomputer is called microprocessor.  It is a CPU on a single chip (microchip).  It is called brain or heart of the computer system.  It is the processing unit of the computer system responsible for carrying out the processing job i.e execution of program.

Microprocessor (Contd…) Components of Microprocessor 1.ALU: Arithmetical and Logical unit responsible to perform Arithmetical (mathematical) and logical (comparison) operation of the data.

Microprocessor (Contd…) Components of Microprocessor 2. Control Unit:  Control Unit of the computer controls all the functions like input, output, storage and process.  It controls the flow of data/program between Main MemoryCPU Registers I/O deviceMain Memory  This unit decode the instruction and generate the control signal on the basis of instruction and instruct the ALU which operation is to be performed.

Microprocessor (Contd…) Components of Microprocessor 3. Registers:  Registers are the high speed temporary storage place where all the processing done by the ALU.  The few typical registers used in a CPU are Accumulator, Program Counter (PC), Instruction Register (IR), Memory Address Register (MAR) and Memory Data/Buffer Register (MBR/DR).

Microprocessor (Contd…) Instruction Execution For every instruction the CPU carries out four basic operations: i) Instruction Fetch (IF) ii) Instruction Decode (ID) iii) Instruction Execute (IE) iv) Result Store (RS)

Microprocessor (Contd…) Instruction Execution (Contd…) Instruction/Machine Cycle:  These four basic operation performed by the CPU in called instruction cycle.  The instruction cycle consist of fetch cycle and execute cycle.

Microprocessor (Contd…) Instruction Execution (Contd…) Fetch Cycle:  Instruction fetch involves reading of an instruction from the memory location to the CPU register. Execute Cycle  This cycle involves execution of the instruction.

Microprocessor (Contd…) Register Organization Typical register used in CPU are: Accumulator: It interact with ALU and stores the input or output operand. Data Register (DR): It contains the data to be written in the memory (write operation) or it receives the data from the memory (read operation). It also holds the instruction before storing in Instruction Register. Memory Address Register (MAR): It specifies the address of memory location from which data or instruction is to be accessed (for read operation) or to which the data is to be stored (for write operation). Program Counter (PC): It contains the address of next instruction to be executed. Instruction Register (IR): Holds the current instruction.

Microprocessor (Contd…) Fetch Cycle During this cycle the instruction which is to be executed next is brought fro the memory to the CPU.