COMPUTER
• The term "Computer" is derived from the Latin word "Computare" which means "to compute"
or "to calculate."
• Computers are machines that perform tasks or calculations according to a set of instructions
or programs.
• It is an electronic device used to store data and gives the results accurately within a fraction of
second.
GENERTION OF COMPUTER
Computers can be categorized into different generations based on their technological
advancements and the underlying hardware and architecture.
1. First Generation (1940s-1950s):
- Characterized by vacuum tube technology.
- Large, expensive, and unreliable.
- Examples include ENIAC and UNIVAC.
2. Second Generation (1950s-1960s):
- Transition to transistor technology from vacuum tubes.
- Smaller, faster, and more reliable than first-generation computers.
- Examples include IBM 1401 and CDC 1604.
3. Third Generation (1960s-1970s):
- Introduction of integrated circuits (ICs) and smaller transistors.
- Greater speed, reliability, and reduction in size and cost.
- Examples include IBM System/360 and DEC PDP-11.
4. Fourth Generation (1970s-1980s):
- Emergence of microprocessors and microcomputers.
- Personal computers (PCs) became accessible to individuals and businesses.
- Examples include IBM PC, Apple II, and Commodore 64.
5. Fifth Generation (1980s-Present):
- Focus on parallel processing, artificial intelligence, and advanced computing.
- Development of supercomputers and high-performance computing (HPC).
- Examples include IBM Watson, Cray supercomputers, and modern CPUs/GPUs.
COMPONENTS OF COMPUTER SYSTEM
• The computer is an electronic device that accepts (reads) data from the user and processes the
data by performing calculations and operations on it, and generates (writes) the desired output.
• A computer consists of four major components such as
➢ Input Devices (Input Unit)
➢ CPU (Processing Unit)
➢ Memory (Storage Unit)
➢ Output Devices (Output Unit)
FIG 1: Components of Computer Input Unit
• An input device is a hardware or peripheral device used to send data to a computer.
• An input device allows users to communicate and feed instructions and data to computers for
processing, display, storage and/or transmission. The important and most commonly used
input devices are
➢ Keyboard
➢ Mouse
• Other input devices are
➢ Joystick
➢ Scanner
➢ Barcode Reader
CPU (Processing Unit)
• The CPU is the heart of the computer, it is the part of a computer which interprets and executes
instruction.
Functional block of CPU
• The two components in CPU are
➢ Arithmetic and logic unit (ALU)
➢ Control Unit (CU)
FIG 2: Functional block of CPU
• Arithmetic and logic unit (ALU)
➢ The ALU performs arithmetic and logical operations.
➢ Arithmetic operations include addition, subtraction, multiplication and division.
➢ Logical operations include comparing numbers, letters and
special characters.
➢ The ALU is a fundamental building block of the Central Processing Unit of a computer.
• Control Unit (CU)
➢ A Control Unit (CU) handles all processor control signals.
➢ It directs all input and output flow, fetches code for instructions from microprograms and
directs other units and models by providing control and timing signals.
• Memory Unit
➢ Computer memory is a device that stores computer's data and programs.
FIG 3: Computer Memory (RAM)
➢ It stores program, data results or any kind of information.
➢ Memory stores binary information, i.e. 0's and 1's in internal storage areas in
the computer.
➢ Moreover, the term memory is usually used as shorthand for physical
memory, which refers to the actual chips capable of holding data.
➢ Some computers also use virtual memory, which expands physical memory
onto a hard disk.
• Output Unit
➢ Output devices are peripheral equipment that converts a computer's output to a form that
can be seen, heard or used as an input for another device, process or system.
➢ The important output devices, which are used in computer systems are Monitors, Printer,
Graphic Plotter.
Characteristics of Computer
• Computers have some important features which have made them so popular.
• A Computer can be categorized according to: -
Speed
Accuracy
Versatility
Reliability
Power of remembering
Diligence
Storage
• Speed
➢ Computers work at an incredible speed.
➢ It can carry out instructions at a very high speed.
➢ A powerful computer is capable of performing about 3-4 million simple instructions per
second.
➢ It can perform arithmetic and logical operations within a fraction of second.
• Accuracy
➢ Computer provides a high degree of accuracy.
➢ Computers perform all jobs with 100% accuracy.
➢ The degree of accuracy of a computer depends on the instruction and processor type.
• Versatility
➢ Computer is versatile in nature.
➢ It can perform different types of task easily.
➢ At one moment user can use the computer to prepare a letter document and in the next
moment they may play music or print a document.
• Power of remembering
➢ A computer can store and recall any information because it has secondary storage.
➢ All information can be retained as long as desired by the user and that can be recalled
almost simultaneously and accurately even after several years.
• Diligence
➢ Computers can perform long and complex calculations with the same speed and accuracy
from the start till the end.
➢ Being a machine, a computer does not suffer from the human traits of tiredness and lack
of concentration.
• Storage
➢ Large volume of data and information can be stored in the computer and also retrieved
whenever required.
➢ Computer has two types of storage. They are Primary storage and Secondary storage.
➢ In Primary Storage, a limited amount of data can be stored temporarily like RAM, ROM.
➢ Secondary storage can store a large amount of data permanently like floppy and compact
disk.
