1.Introduction2.Types of Software 2.1.System software 2.2.Application software3.Security of a system 3.1.Basic Components of Computer 3.2.Threats to Computer security 3.3.Solutions to computer Security Threats

The proficiency, versatility and processing speed of desktop computers have advanced to such an extent that any type of information and data processing is like a child’s play to the machines which are now available.

Over the years , professional programmers have come out with incredible software and programs to enable our desktop computer to perform almost any type of task.This chapter is dedicated to the “ computer software ” that played a very important role in making computers a household name.

1.Single Program OS. As the name suggests , this OS is single user operating system , so only one user program can be supported and executed by it at any point.

2.MultiProgram OS. It supports multiprogramming.i.e., more than one user can be supported by it, therefore ,more than one user programs are loaded and active in the main store at he same time.3.Time Sharing OS. This OS uses the time sharing technique. Each active user program is given a fair share of CPU time(δ),if the time elapses or an I/O operation is requested, CPU shifts over to the next jobs waiting and the previous program4.Real Time os: The jobs have fixed deadlines and the jobs have to be completed within their deadlines. the system performance is measured by its ability to complete its jobs within specified deadlines. If a job cannot be complete within its deadline, its situation is called deadline overrun.5. Multiprocessing os: The Multiprocessing os is capable of handling more than one processors as the have to be executed on more than one processor(CPU)

Assembler: It translates(converts) the assembly language program into an equivalent machine language program.Compiler: It Translate(convert) the Entire HLL program into machine language program in one go, and reports all errors of the program along with the line numbers.

Interpreter: It Translate(convert) the HLL program into machine language program line by line.

It is a set of programs necessary to carry out operations for a specified application.

Electronic Spreadsheets: An Electronic spreadsheet is a program that accepts data in a tabular form( in rows and columns) and allows to manipulate/calculate/analyze data in the desired manner.

Examples: Exel,Lotus1-2-3 etc. Database Management system (DBMS):

It is a package that can handle and manage bulk of stored data.

Desktop Publishing Packages: The software that handles page layout by combining the functions of a traditional typesetter and a layout artist, is known as desktop publishing software.

Graphics Software: The application software that manipulates images is known as graphic software.

multimedia software: the software the incorporates images , text, sound, computer animation, and video sequences is known as multimedia software.

Presentation Graphic software: The application software that can create professional looking visual aids.

Utilities: Utilities are those application programs that assist that the computer by performing housekeeping functions like backing up disk or scanning/cleaning viruses or arranging information etc. Text Editor: It is used for creating, editing text files. It supports special commands for text editing i.e., You can insert, delete, find, replace characters, lines and paragraphs etc.

Backup Utility: This utility program facilitates the backing up of disk. Back-up means duplicating the disk information so that in case of any damage or data-loss, this back up data may be used. Compression Utility: This utility program facilitates compression of files.Large files can be compression so that they take less storage area. When needed ,these compressed files can be exploded back to their original form. Disk Defragmenter: A defragmenter program is a utility which reorganises the data on the disk so that all blocks for a file are stored together to improve access times. This should be done regularly to maintain hard disk performance. This utility program attempts to minimize the fragmentation on your disk . A file is fragmented when it becomes too large for your computer to store in a single location on a disk.

Antivirus Software: It ensures virus –free work environment. A virus is a program or programming code that replicates by being copied or initiating its copying to another program, computer boot sector or document..

This type of software is tailor made software according to a business requirements.This type of software is developed to meet the general requirements of a business.Examples of these software are Inventory Management System,Payroll system,Financial Accounting,Hotel Management And Reservation system etc

When Programmer develop a software for any type of application,they need an array of tools that helps them accomplish their task.Some commonly used developer tools are :1.Compilers 2.Interpreters 3.Integrated Development Environment

IDE is an application program consisting of different development tools needed for developing an application.

An IDE typically consists two or more of the following tools:1.Source Code editor2.Compiler3.Debugger4.Graphical User Interphase builder5.Build automation tools6.Code Generator

Computer Security is a ability of a system to protect info and system with respect to confidentiality and Integrity.

1.Confidentiality:Ensuring that information is not accessed by unauthorised persons.2.Integrity:Ensuring that info is not altered by unauthorised persons.3.Authentication:Ensuring that users are the persons they claim to be.

A Threat is a potential Violation of security.When a threat is actually executed, it becomes attack.

Some common Threats to avg computer faces are1.Virus 1.1.Worms 1.2.Trojans2.Spyware3.Adware4.Spamming5.PC Intrusion 5.1.Denial of Service 5.2.Sweeping 5.3.Password guessing6.Phising

Computer virus are malicious codes/programs that cause damage to data and files on a system

Spamming refers to the sending of bulk mail by an Identified/unIdentified Source.Damage caused by it are:1.Spam reduces Productivity2.Spam Eats up your time3.It can lead to worse things

1.Denial of Service:this type of attack eats up all resources of a system and applications aome to halt. 2.Sweeping: this is another malicious one.it sweeps i.e.,deletes all data of pc 3.Password guessing: hackers crack or guess password of pc accounts and gain entry into remote pc systems

It is criminally fraudulant process of attempting to acquire sensitive info like username,password,creditcard details, etc.

Two categorization of solutions are:1.Active Protection2.Preventive Measures

Active ProtectionInstalling and properly using anti-virus software that includes internet security-which includes Protection against all malware.

Preventive MeasuresEven though security programs may actively detect and eliminate any threats to PC

encounters,you should always help prevent these issues from ever arising.

(a) Use anti-virus and anti-spyware software. (b) Download updates regularly.(c) Run frequent full-system scans.

(a) Keep your system up-to-date(b) Use caution when Downloading files on the interenet.(c) Be careful with Email.(d) Disable Cookies,if possible

Cookies are small files created on client computer when these systems browse certain Web-sites.

(A) Use Anti-Spam Software 1.Sender Filtering It is done on the basis of Digital Certificates and signatures. 2.Keyword Filtering

1 Keep your email address private.2 Use Alternate Style of Writing your email address on the web.

Solutions to Pc IntrusionSolutions to Pc Intrusion

1.Use proper File access permissions when sharing files on internet.File Access Permission refers ro the privilage that allows a user to read,write,or execute a file.2.Disconnect from internet when away.

=>A cookie (also known as a web cookie, browser cookie, and HTTP cookie) is a small bit of text or a file that accompanies requests and pages as they go between the web server and browser. The cookie is sent as an header by a web server to a web browser and then sent back by the browser each time it accesses that server. Cookies help web sites to store information about visitors.=> Digital Certificates: A formatted digital information issued to website , are used to verify the identity to the message sender to the recipient by generating a digital signature that can be used to sign the message.

=>A digital certificate (also known as a public key certificate or identity certificate) is an electronic document which uses a digital signature to bind together a public key or

password required for decode and encoded document with an authentic identity such as

the name of a person or an organization, their phone numbers or address, and so forth.

The certificate can be used to verify that a public key belongs to an authorized individual

or organization.