Think for a minute about Think for a minute about the computer system you the computer system you use. It probably has a use. It probably has a monitor, a mouse, and a monitor, a mouse, and a case that contains case that contains electronic components electronic components such as a hard disk and such as a hard disk and the CPU (the computer’s the CPU (the computer’s “brain”). “brain”).

These physical components are called hardware. They are the parts of the computer system that we can actually see and touch.

You may wonder how this You may wonder how this computer hardware computer hardware knows what it is knows what it is supposed to do.supposed to do.

The answer is that we The answer is that we give it instructions.give it instructions.These instructions are These instructions are called software or called software or programs.programs.

All software can be All software can be divided into two main divided into two main categories:categories:

• Operating systems• Operating systems• Application software• Application software

Operating SystemsOperating Systems

Each time you start your Each time you start your computer, the computer computer, the computer loads the operating loads the operating system (OS) into the system (OS) into the computer’s memory so computer’s memory so that it can be used. This that it can be used. This process is sometimes process is sometimes called booting the called booting the system.system.

The operating system The operating system acts as an interface, or acts as an interface, or link, between the user link, between the user and the computer and the computer hardware.hardware.

There are four main jobs There are four main jobs an operating system is an operating system is responsible for:responsible for:

1.1. It provides a user It provides a user interface. The user interface. The user interface lets you give interface lets you give commands to the OS.commands to the OS.

2. It gives instructions to 2. It gives instructions to the computer hardware, the computer hardware, such as the printer and such as the printer and monitor.monitor.

3. It manages the way in 3. It manages the way in which the computer which the computer stores data and stores data and applications.applications.

4. It keeps track of 4. It keeps track of different jobs. For different jobs. For example, if you are using example, if you are using both a spreadsheet and a both a spreadsheet and a word processing word processing application at the same application at the same time, the OS will run both time, the OS will run both of these applications and of these applications and let you switch back and let you switch back and forth between them.forth between them.

There are only few There are only few Operating Systems that Operating Systems that are commonly used in are commonly used in microcomputers: microcomputers:

Microsoft Windows, Apple Microsoft Windows, Apple Macintosh, Linux and Macintosh, Linux and UnixUnix

ApplicationsApplications

Applications are software Applications are software programs that perform programs that perform specific tasks for us. You specific tasks for us. You have probably used many have probably used many different types of different types of applications.applications.

Activity management Activity management programs likeprograms likecalendars and address calendars and address booksbooks

• • Word processing Word processing applications forapplications forcreating documents that creating documents that are attractivelyare attractivelyformattedformatted

• • Spreadsheet Spreadsheet applications for creatingapplications for creatingdocuments to manage documents to manage and organizeand organizenumerical datanumerical data

• • Presentation Presentation applications for making applications for making slide showsslide shows

• • Graphics applications Graphics applications for editingfor editingpicturespictures

• • Database applications Database applications for developing databases for developing databases that can organize and that can organize and retrieve large amounts of retrieve large amounts of informationinformation

• • Communications Communications programs like e mail and programs like e mail and faxing software for faxing software for sending and receiving sending and receiving messagesmessages

• • Multimedia applications Multimedia applications for creating video and for creating video and musicmusic

• • Utilities for performing Utilities for performing a variety of tasks that a variety of tasks that maintain or enhance the maintain or enhance the computer’s operating computer’s operating systemsystem

UtilitiesUtilitiesUtility programs are Utility programs are generally fairly small. generally fairly small. Each type has a specific Each type has a specific job to do. Below are some job to do. Below are some descriptions of utilities.descriptions of utilities.

• • Anti-virus applications Anti-virus applications protect your computer protect your computer from the damage that can from the damage that can be caused by viruses and be caused by viruses and similar programs.similar programs.

• • Compression utilities Compression utilities make files smaller for make files smaller for storage (or sending over storage (or sending over the Internet) and then the Internet) and then return them to normal return them to normal size.size.

• • Data recovery utilities Data recovery utilities attempt toattempt torestore data and files restore data and files that have been damaged that have been damaged or accidentally deleted.or accidentally deleted.

• • Disk defragmenters Disk defragmenters reorganize thereorganize thedata stored on disks so data stored on disks so that it is more efficiently that it is more efficiently arranged.arranged.

• • Firewalls prevent Firewalls prevent outsiders from accessing outsiders from accessing your computer over a your computer over a network such as the network such as the Internet.Internet.

Both operating system Both operating system software and software and applications have applications have specific jobs to specific jobs to perform. It is perform. It is important to realize important to realize that the OS you arethat the OS you areusing must be using must be compatible with your compatible with your hardware.hardware.