What is CPU? Describe briefly,
CPU stands for central processing unit. It is the brain of the 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 carries out most of the work of a computer. CPU Performs all operations on data according to the given instructions. It executes instructions and tells other parts of computer what to do. Most of the work consists of calculations and data transfer. CPU consists of two main units:
1. ALU (arithmetic and logic unit)
2. CU (control unit)
1.ALU (Arithmetic and Logic Unit)
ALU is a part of CPU. Actual execution of instructions takes place in this part. All arithmetic and logical operations are performed in ALU. It consists of two units:
1. Arithmetic unit 2. Logic unit
i. Arithmetic Unit
Arithmetic unit of ALU performs basic arithmetic functions such as addition, subtraction, multiplication and division.
ii. 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 CPV. It acts like a supervisor of the computer. It controls all activities of computer system. It performs the following operations.
1. It fetches instruction from main memory.
2. It interprets the instruction to find what operation is to be performed.
3. It controls the execution of instruction.
What is main memory? Describe its structure. How data stored in main memory is accessed?
Main memory is an important component of computer system. It is used to store program and data that are being used. It is also known as working area of a computer system. A computer cannot work without main memory.
Structure of main memory
Main memory in the modern computer is built in the form of a chip. The chip is made of a semi conductor material. The chip consists of thousands or millions of cells. Each cell can store one bit i.e. 0 or 1.
The cells in main memory are logically organized as groups of 8 bits. One group of 8bits is known as byte. Each byte in the memory is assigned a unique number. This number is known as the address of the byte.
Accessing data in main memory
Main memory is a sequence of bytes. CPU and other components can access any byte of main memory by specifying its address. Different bytes can be accessed randomly. The memory is built from electronic components. Accessing any part of memory takes equal time.
No mechanical movement is required when data is accessed from main memory. That is why the main memory is very fast as compared to other storage devices such as magnetic disk etc. there are two types of memory known as RAM and ROM.