The central processing unit (CPU) is the brain of computer. It is the most important component of a computer. It is also called processor. A computer cannot work without CPU. All computers must have a central processing unit.CPU is located on the motherboard. It performs all operations on data according to the given instructions. It can perform arithmetic and logical operations like addition, subtraction etc. It executes instruction and tells other parts of computer what to do. CPU consists of two main units called ALU (Arithmetic and Logic Unit) and CU (Control unit).
1. ALU (Arithmetic and Logic Unit)
ALU is a part of CPU. Actual execution of instruction takes place in this part. All arithmetic and logical operations are performed in ALU. It consists of two units:
a)Arithmetic Unit
Arithmetic unit of ALU performs basic arithmetic functions such as addition, subtraction, multiplication and division.b)Logic Unit
Logic unit of ALU performs logical operations like comparing two data items to find which data item is greater than, equal to, or less than the other.
Control unit is an important component of CPU. It generates signals to direct the entire computer system. It controls and coordinates all activities of computer system. It does not execute program instruction by itself. It directs other parts of computer to perform different tasks. Control unit communicates with arithmetic and logical unit, memory and other parts of computer system. Control unit also provides clock pulses. The pulses are used to regulate and control the speed of all operations in computer.
Register:
A register is a small high-speed memory inside CPU. The CPU contains a number of registers. Registers are used to store information being processed. These are temporary storage areas for instructions or data. The temporary results during processing are also stored in registers. Each register has a predefined function. Control unit manages registers for the following purposes:
- Input the instructions or data
- Store the instruction or data
- Transfer the instructions or data
- Perform arithmetic or logical operations at high speed.