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Peripheral Devices• “Peripheral devices” are hardware plugged into

ports or connected to a computer wirelessly.• These devices can be for input, output, or both.• Monitors provide a visual display on a screen.

The two common types of monitors are– cathode-ray tub (CRT)– liquid crystal display (LCD)

• Modems transmit data by converting digital signals to analog signals and vice versa. This allows computers to communicate over phone lines.

• Expansion cards contain chips that add new features to a computer, such as a graphics card.

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Peripheral Devices(continued)

• Printers print text and graphics on paper. They can be impact or non-impact.

• Pointing devices control the movement of a cursor on the display screen. Examples include the mouse, the trackball, and the touch pad.

• Graphic tablets are a type of pointing device used by graphic designers.

• Gamepads are input devices controlled by a user’s thumbs.

• Keyboards enable users to enter data.

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Peripheral Devices(continued)

• Speakers allow the output of sound.• Microphones input sound to a computer.• Scanners allow documents and pictures to

be scanned into the computer and to be stored in a digital file.

• Webcams take pictures and videos that can be uploaded to the Web.

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Computer Software

• Computer software carries out the four functions (input, storage, processing, and output).

• Software is a set of electronic instructions that tell a computer what to do. A computer must have software.

• There are two types of software:1. operating software

2. application software

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Operating System Software

• The operating system software - recognizes data coming from an input device- sends information to an output device- keeps track of directories and files-controls peripheral devices- responsible for running software and for security.

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Some popular operating systems are:

Microsoft Windows - for PCs

Mac OS - for Apple computers

Linux - for very large network computers

Handheld operating systems - for PDAs, MP3 players, and cell phones

What Is a GUI?

Nearly all modern operating systems use a graphical user interface (GUI). This lets users click on images or text on the screen instead of having to type commands.

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Application Software

• Application software is designed to allow users to perform specific tasks.

• Application software is categorized by its function:– utility

– productivity (word processing, spreadsheet, database, presentation)

– desktop publishing

– graphics

– Web development

– Internet browser

– computer games

– communications

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• How Do I Use Software?It is important to choose the right software program for the type of task

you want to do:

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Desktop

• A “desktop” is a computer case designed to sit on your desk.

• It is also the primary screen on your computer.

• The appearance depends on interface:–menu-driven–command-driven

• Most desktops use a graphical user interface (GUI) with windows, icons, and pop-up menus.

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Typical Desktop Features

• Typical desktop features include

- wallpaper

- icons

- taskbar/menu bar

- windows

- screensaver

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Computer Communication

• To communicate, computers must be linked via a network.–A network is two or more computers connected

by cable or radio signals.

• A computer that is not part of the network is a called a stand-alone.

• The two advantages of a network are–access to information–access to equipment

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A network allows you to send data back and forth between different computers, servers, storage devices, and shared output devices:

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Types of Networks

• There are two types of networks:

1. A local area network (LAN) is located in one building.

2. A wide area network (WAN) covers a large geographic area.

• Networks are arranged in two ways:1. client/server

• One computer is the leader, or the server.• The other computers (also called nodes) are clients.

2. peer-to-peer• All computers act as both clients and servers.

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Network Topologies

• A topology is the physical layout of computers.

• There are two main topologies:1. bus

• All nodes and peripherals are attached to one main cable.

2. star• All nodes and peripherals are attached to a central

hub.