COMPUTER SOFTWARE

WHAT IS ……. Computer software is any set of machine

readable instructions that directs a computer’s processor to perform specific operations.

It is a set of programs, procedures, functions, associated data and/or its documentation, if any.

Software is a general term. It can refer to all computer instructions in general, or to any specific set of computer instructions.

TYPES OF SOFTWARE

Software

System Application

SYSTEM SOFTWARE

System software is computer software designed to operate the computer hardware, to provide basic functionality, and to provide a platform for running application software.

System software also includes the boot firmware, which loads (or in some cases constitutes) the operating system. Firmware is software that has been permanently stored in hardware (specifically, in non-volatile memory). Thus, it has qualities of both software and hardware, but it is still software.

SYSTEM SOFTWARE

System software

Operating Systems

Device Drivers

Servers

Utilities,Compilers

Window Systems

OPERATING SYSTEMSAn operating system (OS) is a collection of software that manages computer hardware resources and provides common services for computer programs. Application programs usually require an operating system to function.

OS perform basic tasks such as recognizing input from the keyboard, sending output to monitor, keeping track of files and directories on disk and controlling peripheral devices such as disk drives and printers.

eg: Microsoft Windows, Linux, OS/2 etc.

OPERATING SYSTEM

UTILITIESUtility software is system software designed to help analyze, configure, optimize or maintain a computer.

It performs a very specific task, usually related to managing system resources.

Examples Anti-virus utilities scan for computer viruses. Backup software can make copies of all

information stored on a disk and restore either the entire disk.

Disk cleaners can find files that are unnecessary to computer operation, or take up considerable amounts of space. Disk cleaner helps the user to decide what to delete when their hard disk is full.

APPLICATIONS SOFTWARE & PACKAGES Application software were historically defined

as all the software that uses the computer system to perform useful work (or entertainment functions) beyond the basic operation of the computer itself.

However, in practice the distinction between system software and application software is often blurred due to bundling of useful applications with the operating system.

Includes data base programs, word processors, spreadsheets etc.

APPLICATION SOFTWARE

Application software

Image Processors

Word processors,Spreadsheets

Web Browsers

Games,Communication Software

Database systems

Mobile and Tablet Apps.

OTHER TERMS Plug-ins are software that extends or

modifies the functionality of another piece of software, and require that software be used in order to function

Embedded software resides as firmware within embedded systems, devices dedicated to a single use or a few uses such as cars and televisions.

TYPES OF SOFTWARE PACKAGES1. Word processors

Word processing is usually what leads people to using a computer for their work. Word processors will normally have the following capabilities built into them: 

Spell checking Standard layouts for normal documents Have some characters appear in bold print, italics, or

underlined Center lines, make text line up on the left side of the paper,

or the right side of the paper Save the document so it can be used again print the document.

Two of the most common word processing programs are WordPerfect and Microsoft Word.

The spreadsheet packages are designed to use numbers and formulas to do calculations with ease.  Examples of spreadsheets include:

Budgets Payrolls Grade Calculations Address Lists The most commonly used spreadsheet

programs are Microsoft Excel and LibreOffice Calc.

3. Databases Database programs are designed for these

types of applications: Membership lists Student lists Grade reports Instructor schedules Some common database programs are

Microsoft Access and

4. Graphic Presentations The presentation programs can make giving

presentations and using overheads easier.  Other uses include:  Slide Shows

Repeating Computer Presentations on a computer monitor

Using Sound and animation in slide shows  The most recognized graphic presentation

programs are Microsoft PowerPoint and LibreOffice Impress.

5. Web Browsers Web Browsers provide an easy to surf the Internet.

Use search engines to find people, places, and things world-wide.

Create your own web page to tell the world about you and your job.

Advertise your company and special activities.

The two most popular web browsers are Mozilla Firefox and Microsoft Internet Explorer.

DATABASE MANAGEMENT PACKAGES

A database is a large collection of data entered a computer system and stored for future use. The computerized information in the database is organized so that the parts that have something in common can be retrieved easily. Most DBMS packages can perform four primary tasks:

Database Development: Define and organize the content, relationships, and structure of the data needed to build a database.

Database Interrogation: Access the data in a database for information retrieval and report generation. A user can selectively retrieve and display information and produce printed reports and documents.

Database Maintenance: Add, delete, update, correct, and protect the data in a database.

Application Development: Develop prototypes of data entry screens, queries, forms, reports, and labels for a proposed application.A database management package or database management system (DBMS) is a software package used to set up, or structure, a database. It is also used to retrieve information from a database.

GRAPHICS PACKAGESA graphics program can display numeric data in a visual format for analytical or presentation purposes.

Draw and Input graphics packages support freehand drawing, while desktop publishing programs provide pre-drawn clip art graphics for insertion into documents. Popular business graphics packages are Freelance, Corel Draw etc.

TYPES OF GRAPHICS PACKAGES

Analytical

GraphicsPresenta

tion Graphics

There are two types of graphics programs. Analytical graphics programs are used to analyze data.Graphics may take the form of bar charts, line graphs, pie charts etc.

Most analytical graphics programs come as part of spreadsheet programs. They are helpful in displaying economic trends, sales figures, and the like for easy analysis. Analytical graphics may be viewed on a monitor or printed out.

.

Presentation graphics programs are used to create attractive finished graphs for presentations or reports.

Users can use presentation graphics to communicate a message or to persuade other people, such as supervisors or clients. Thus, presentation graphics are used by marketing or sales people, High-end presentation graphics packages even include animation capabilities.

COMMUNICATION PACKAGESCommunications software enables a microcomputer to send and receive data over a telephone or other communications line.

Common features of microcomputer communications programs are as follows:

Data Banks: With a communications program, users can access enormous computerized databases - data banks of information.

Message Exchanges: Communications programs enable users to leave and receive messages on electronic bulletin boards or to use electronic-mail services. Electronic bulletin boards exist for people interested in swapping all kinds of software or information.Many organizations now have electronic mailboxes. For instance, users can transmit a report users have created on users word processor to a far away company executive or to a college instructor.

Financial Services: With communications programs, users can look up airline reservations and stock quotations and even do home banking and bill paying.

OPERATING SYSTEM……The OS software must keep track of each h/w resource, determine who gets what, determine when the user will have access to the resource, allocate how much of the resource the user will be given, and terminate access at the end of the use period.

An operating system is a group of computer programs that coordinates all the activities among computer hardware devices. It is the first program loaded into the computer by a boot program and remains in memory at all times.

Operating Systems vary in complexity from those that support single user micro computers to those that handle multiuser main frames.

The complexity depends on the computer systems’ size and scope, together with the type of performance provided to its users.

A single stand alone micro computer will have a relatively simple OS, whereas a mainframe that supports hundreds of users accessing the system simultaneously, will have a complex OS.

FUNCTIONS OF AN OS.The basic functions of an operating system are: Booting the computer Performs basic computer tasks eg managing the

various peripheral devices like mouse, keyboard Provides a user interface, e.g. command line,

graphical user interface (GUI) Handles system resources such as computer's

memory and sharing of the central processing unit (CPU) time by various applications or peripheral devices

Provides file management which refers to the way that the operating system manipulates, stores, retrieves and saves data.

BOOTING THE COMPUTER

The process of starting or restarting the computer is known as booting.

A cold boot is when you turn on a computer that has been turned off completely.

A warm boot is the process of using the operating system to restart the computer.

PERFORMS BASIC COMPUTER TASKS

The operating system performs basic computer tasks, such as managing the various peripheral devices.For example, most operating systems now are plug and play which means a device such as a printer will automatically be detected and configured without any user intervention.

PROVIDES A USER INTERFACE

A user interacts with software through the user interface.

User interface can be Command line

Graphical user interface (GUI). With a command line interface, the user interacts with the operating system by typing commands to perform specific tasks.

With a graphical user interface, the user interacts with the operating system by using a mouse to access windows, icons, and menus.

The two main types of user interfaces are: command line and a graphical user interface (GUI). With a command line interface, the user interacts with the operating system by typing commands to perform specific tasks. An example of a command line interface is DOS (disk operating system). With a graphical user interface, the user interacts with the operating system by using a mouse to access windows, icons, and menus. An example of a graphical user interface is Windows Vista or Windows 7.

HANDLES SYSTEM RESOURCES

The OS handles system resources such as the computer's memory and sharing of the central processing unit (CPU) time by various applications or peripheral devices. Programs and input methods are constantly competing for the attention of the CPU and demand memory, storage and input/output bandwidth.

The operating system ensures that each application gets the necessary resources it needs in order to maximize the functionality of the overall system.

PROVIDES FILE MANAGEMENT

The operating system also handles the organization and tracking of files and directories (folders) saved or retrieved from a computer disk. The file management system allows the user to perform such tasks as creating files and directories, renaming files, copying / moving files, and deleting files.

CLASSIFICATION OF OPERATING SYSTEMS(1) Multiuser(2) Multiprocessor(3) Multiprogram(4) Multitasking(5) Multithreaded(6) Time sharing (7) Real time etc..

MULTI USER OS A multiuser system is one that can be

used by more than one user. The system provides an environment in

which many users can use the system at the same time or exclusively at different times.

Each user can execute applications without any concern about what other users are doing in the system.

When many users run their applications at the same time, they compete for system resources.

The operating system allocates them the resources in an orderly manner.

Security is a major design issue in multiuser operating systems.

Each user has a private space in the system where the user maintains own programs and data, and the operating system must ensure that this space is visible only to the user and authorized ones, and is protected from unauthorized and malicious users.

The system needs to arbitrate resource sharing among active users so that nobody is starved of system resources.

Multiuser systems may need an accounting mechanism to keep track of statistics of resource usage by individual users.

MULTIPROCESSOR SYSTEMS

A multiprocessor system is one that has more than one processor on-board in the computer.

They execute independent streams of instructions simultaneously.

They share system buses, the system clock, and the main memory, and may share peripheral devices too.

There are two primary models of multiprocessor operating systems: symmetric and asymmetric.

In a symmetric multiprocessor system, each processor executes the same copy of the resident operating system, takes its own decisions, and cooperates with other processors for smooth functioning of the entire system.

In an asymmetric multiprocessor system, each processor is assigned a specific task, and there is a designated master processor that controls activities of the other subordinate processors. The master processor assigns works to subordinate processors.

MULTIPROGRAM SYSTEMS

A multiprogram system is one where many application programs can reside in the main memory at the same time.

Applications definitely need to share the main memory, and they may also need to share other system resources among themselves.

Memory management is a major design challenge in multiprogram operating systems. Multiplexing of the main memory is essential to hold multiple applications in it. Different standalone applications should be able to share common subprograms and data.

Processor scheduling is another design issue in such systems as the operating system needs to decide the best applications to bring in the main memory.

Protection of programs from their own executions is another issue in designing such systems.

MULTI TASKING SYSTEMMulti tasking is one that executes many processes concurrently.Many processes are executed concurrently to improve the performance of the system, and to improve the utilization of system resources such as the processor, the main memory, disks, printers, network interface cards, etc.

TIME-SHARING SYSTEMS

Time sharing system allows many users to share the computer resources simultaneously. In other words, time sharing refers to the allocation of computer resources in time slots to several programs simultaneously. For example a mainframe computer that has many users logged on to it. Each user uses the resources of the mainframe -i.e. memory, CPU etc. The users feel that they are exclusive user of the CPU.

REAL TIME OSReal Time System is used at those Places in which we Requires higher and Timely Response. These Types of Systems are used in Reservation. So when we specify the Request, the CPU will perform at that Time.

The time to display the Results after Possessing has fixed by the Processor

The time sharing system provides the direct access to a large number of users where CPU time is divided among all the users on scheduled basis. The OS allocates a set of time to each user. When this time is expired, it passes control to the next user on the system. The time allowed is extremely small and the users are given the impression that they each have their own CPU and they are the sole owner of the CPU. This short period of time during that a user gets attention of the CPU; is known as a time slice or a quantum

TIME SHARING SYSTEMS

MULTITHREADING OSMulti threading is an ability of an OS to execute different parts of a program called threads, simultaneously.

The programmer must carefully design the program in such a way that all threads can run at the same time without interfering with each other.