2-3 note

2 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 –c–cathode-ray tub (CRT) –l–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.

3 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.

4 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.

5 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

6 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.

7 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. 7

8 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

9 How Do I Use Software? It is important to choose the right software program for the type of task you want to do: 9

10 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.

11 Typical Desktop Features Typical desktop features include - wallpaper - icons - taskbar/menu bar - windows - screensaver

12 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

13 A network allows you to send data back and forth between different computers, servers, storage devices, and shared output devices: 13

14 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.

15 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.