Computer:
A Computer is an electronic device which can accept data, apply a series of logical operations and supply the result of these operations as informations.
Characteristics of Computers
i) Speed: The speed of electronic computers is very fast, which is same as that of light. Thus millions of calculations can be done in a second.ii) Storage and Retrieval of Information: Computer can store large amount of data, instruction and information on its secondary memory device and same can be accessed and retrieved.
iii) Accuracy: The accuracy of the computer is consistency very high.
iv) Diligence: Computer is a machine so it does not suffer from the human traits like tidiness, lack of concentration. It does not suffer from monotony and boredom.
v) Automation: Once the programme is fed into the the computer memory the individual instruction are then transferred one after the other to the CPU for execution.
vi) Versatility: Computer in fact is capable of performing almost any job which can be instructed by series of logical steps.
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BASIC ELEMENTS OF COMPUTER SYSTEM
INPUT UNIT AND DEVICES
The input unit accept the data of instructions given by the order and converts these from man readable form to computer readable code. Input devices are used to transfer the information into the computer.
Function of input unit and devices are:i) It accepts the data and list of instructions from outside.
ii) It converts these data and instruction in computer acceptable form.
iii) It supplies the converted instructions and data to the computer further processing.
Input devices are:
Keyboard
Mouse
MICR reader
Optical character reader
Magnetic tape unit
Magnetic disc unit
Floppy disc etc
OUTPUT UNIT AND DEVICES
The functions of the output devices is to get information out of the CPU.
Function performed by output unit and devices are:i) It accepts the results produced by the computer which are in coded form.
ii) It convert these coded results to human readable form.
iii) It supplies the result to the outside world.
Output devices are:
Printer
Monitor
VDU
CENTRAL PROCESSING UNIT (CPU)
The CPU is the brain of a Computer system. It provides central control of the functions of the computer.Function performed by CPU are:
i) to store data as well as progamme
ii) to control the sequence of operations as per stored instructions.
iii) to issue commands to all parts of the computer system.
iv) to carry data processing and send result to output unit.
CPU contains three part:
i) A Memory unit
ii) A Control unit
iii) An Arithmetic & Logic unit(ALU)
MEMORY UNIT
Memory unit is a random access storage device, consisting of a number of storage locations.The memory unit has the compatibility to store information. It is used to store both the programme and data.
CONTROL UNIT
The control unit directs all operations inside the computer. The control unit is designed to coordinate the representation, storage and internal movement of insturction and data, as well as the interpretation and subsequent execution of these instructions and it then has to pass the results.ARITHMETIC LOGIC UNIT
It is the part of CPU where all the arithmetical and logical operations are performed.The arithmetic unit performs the functions of addition, subtraction, multiplication, division, etc. It performs all these functions in the forms of addition.
The logical section of ALU performs all the logical functions and handles various conditions occurring during programme execution. It takes appropriate action based on the instructions, provided by the programmer.
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ELEMENTS OF COMPUTER SYSTEM
HARDWARE
The term hardware is applied to all physical component i.e mechanical, electrical, electronic or magnetic devices that can be seen, touched, repaired, replaced.Three basic components of hardware
a)input section b) CPU c) Output section
SOFTWARE
Software are a collection of programmes i.e. logical instructions written to bring the hardware of a computer system into operations of a data processing system.Software are grouped into two classes:
i) System Software ii) Application Software
System Software
The Programmes which are essential for computer to function is known as System Software. Without these Software, no interaction is possible with computers.
Examples are : Operating System, Device drives, Utitlity programmes
Application Software
The Programmes which are prepared for a particular type of application is known as Application software.
Examples are: Word processor, Spread Sheets, Database Management System.
MEMORY
The functions of memories are to store programme, data and results. There are two types of memories: semiconductor memories and magnetic memories. Semiconductor memories are faster, smaller, lighter and consume less power. Semiconductor memories are used as the main memory of computer. Magnetic memories are used as the secondary memories of a computer for bulk storage of data and information.There are two types of Semiconductor Memories : RAM (Random Access Memory)
ROM (Read Only Memory)
RAM:
This stands for Random Access Memory. It is also called Read/Write memory. Information can be read from and written into it during normal operation. It has random access property. In a random access memory, memory location can be accessed in a random fashion without regard to any other location.ROM:
This stands for Read Only Memory. It is non-volatile. It is used for permanent storage. It has also a random access property. It contains assembler, compiler, monitor, debugging programme or any other permanent programme.The memory of a Computer system may be divided into two main groups: Main Memory and Secondary Memory
Main Memory
The Main Memory of the computer is a fast memory. It is used to store programme and data during computer operation. The memory location of the main memory can be accessed directly by the CPU. Main memory uses semiconductor technology. RAM and ROM ICs are employed for the main memory.Secondary Memory
It is much larger in capacity but slower than main memory. It stores system programmes large data files, assemblers, compilers etc. The information stored in the secondary memory are first transferred to the main memory then processed by the CPU. Final results are again placed in the secondary memory.
COMPUTER VIRUS
Computer virus has become a very serious problem for PC user now a days.Computer virus are basically some programmes designed to replicate and spread, sometimes without indicating that they exists.
Computer virus can produce a variety of symptoms on your PC and in extreme cases can damage your files and hard disk.
Virus may be any one of the following three types:
i) Boot Infectors ii) System Infectors iii) General, .COM and .EXE infectors
Name of the some viruses are
i) Die Hard ii) Dishalf iii) I love you iv) GNB v) GNP etc.
FIREWALL
A software utility and/or hardware device that limits outside network access to a computer or local network by blocking or restricting ports. Firewalls are commonly a great step for helping prevent unauthorized access to a company or home network. The image to the right is a 3Com SuperStack 3 firewall, an example of what a hardware firewall may look like.
ANTI VIRUS PROGRAM
An Anti-virus program is a type of software is designed to protect your computer and/or network against computer viruses. If and when a virus is detected, the computer will generally prompt you that a virus has been found, and ask what action should be done such as deleting the virus.List of Some Antivirus software
AntiVir avast AVG BitDefender
