How Do Computers Work?To accomplish a task using a computer, you need a combination of hardware, software, and input.

1) Monitor A video display terminal.

2) Hard drive Another name for the hard disc that stores information in a computer.

3) Mouse A small hand-held device, similar to a trackball, used to control the position of the cursor on the video display; movements of the mouse on a desktop correspond to movements of the cursor on the screen.

4) Keyboarda keyboard that is a data input device for computers; arrangement of keys is modeled after the typewriter keyboard.

5) Scanner An electronic device that uses light-sensing equipment to scan paper images such as text, photos, and illustrations and translate the images into signals that the computer can then store, modify, or distribute.

6) Printer

A mechanical device for printing a computer's output on paper. There are three major types of printers: Dot matrix: creates individual letters, made up of a series of tiny ink dots, by punching a ribbon with the ends of tiny wires. (This type of printer is most often used in industrial settings, such as direct mail for labeling.) Ink jet: sprays tiny droplets of ink particles onto paper. Laser: uses a beam of light to reproduce the image of each page using a magnetic charge that attracts dry toner that is transferred to paper and sealed with heat.

7) Modem A device that connects two computers together over a telephone or cable line by converting the computer's data into an audio signal. Modem is a contraction for the process it performs: modulate-demodulate.

Hardware consists of devices, like the computer itself, the monitor, keyboard, printer, mouse and speakers. Inside your computer there are more bits of hardware, including the motherboard, where you would find the main processing chips that make up the central processing unit (CPU). The hardware processes the commands it receives from the software, and performs tasks or calculations.

Software is the name given to the programs that you install on the computer to perform certain types of activities. There is operating system software, such as the Apple OS for a Macintosh, or Windows 95 or Windows 98 for a PC. There is also application software, like the games we play or the tools we use to compose letters or do math problems.

You provide the input. When you type a command or click on an icon, you are telling the computer what to do. That is called input.

How They Work Together

First, you provide input when you turn on the computer. Then the system software tells the CPU to start up certain programs and to turn on some hardware devices so that they are ready for more input from you. This whole process is called booting up.The next step happens when you choose a program you want to use. You click on the icon or enter a command to start the program. Let's use the example of an Internet browser. Once the program has started, it is ready for your instructions. You either enter an address (called a URL, which stands for Uniform Resource Locator), or click on an address you've saved already. In either case, the computer now knows what you want it to do. The browser software then goes out to find that address, starting up other hardware devices, such as a modem, when it needs them. If it is able to find the correct address, the browser will then tell your computer to send the information from the web page over the phone wire or cable to your computer. Eventually, you see the web site you were looking for.

If you decide you want to print the page, you click on the printer icon. Again, you have provided input to tell the computer what to do. The browser software determines whether you have a printer attached to your computer, and whether it is turned on. It may remind you to turn on the printer, then send the information about the web page from your computer over the cable to the printer, where it is printed out.

The File Manager is the tool that allows you to manage your hard disk system. It provides visibility into the subdirectory structure of your disks, allowing you to navigate from drive to drive and among the subdirectories and files of each drive. It includes commands that move, copy, and delete single files, single subdirectories, selected groups of files and selected groups of subdirectories. You can rename any file, and any subdirectory. You can search for files, copy diskettes, format diskettes, and view and change the attributes of file. As an alternative to using Program Manager, you can use the File Manager to execute applications. You can associate document files with applications so that when you select the document or any document with the associated file name extension, the File Manager automatically executes the associated application.

File Manager provides a graphical way to organize your files and directories. You can use File Manager to move and copy files, start applications, print documents, and maintain disks.

The File Manager Window

File Manager displays one or more directory windows. A directory window is split, the left half displays a list of directories (the directory tree), and the right half displays the contents of the current directory. When you select a directory in the left half, the contents of that directory are displayed in the right half.

In the directory window, each filename has an Icon next to it, indicating what kind of file it is.

The File Manager is a Window application installed in the Main group. To run it you open the Main group window and select the File Manager.

The File Manager application window has the File Manager menu bar at the top and will contain all of the File Manager’s document Windows and Icons.

Association Files with Applications

When you associate a file with an application, you can open the file and start the application at the same time. If a file is associated with an application, there is a document-file Icon next to the filename in the directory window.

When you start File Manager, some files are already associated with applications.

To associate a file with an application

Select the name of the file you want to associate with an application from the File menu, choose Associate. In the Associate dialog box, select the application you want to associate with the file.

Choose the OK button.

Changing the Look of File Manager

Arranging Windows and Icons

Changing the Font in the File Manager Window

Changing Views in a Director Window

Hiding the Toolbar, Drive Bar, or Status Bar

Moving the Split Bar in a Directory Window

Saving Your Settings

Arranging Windows and Icons

If several directory windows are open or reduced to Icons, you may need to arrange the windows and Icons so that you can see them all.

To arrange directory windows

From the Window menu, choose Cascade to arrange windows so that they overlap (starting in the upper-left corner of the File Manager window) and the title bar of each window remains visible.

Or choose Tile from the Window menu to arrange windows (side by side) so that they do not overlap.

To arrange Icons

From the window menu, choose Arrange Icons.

Changing the Front in the File Manager Window

You can change the font that File Manager uses to display the names of files and directories. You can also change the style and size of the font. Changing the font affects all directory windows and the drive bar.

To change the font

From the Options menu, choose Font.

In the Fong dialog box, select the font, style, and size.

Choose the OK button.

Changing Views in a Directory Window

When you first start File Manager, the left half of the directory window shows the directory tree, and the right half shows the names of all the files and directories in the current directory. You can choose to display only the directory tree or only the directory contents.

To display only the directory tree

From the View menu, choose Tree Only.

To display only the directory contents

From the View menu, choose Directory Only.

Hiding the Toolbar, Drive Bar, or Status Bar

You can display or hide the toolbar, drive bar, or status bar by using the options menu.

To hide the toolbar, drive bar, or status bar

From the Options menu, choose Toolbar, Drivebar, or Status Bar.

The corresponding bar disappears from the File Manager window.

Moving the Split Bar in a Directory Window

You can move the split bar that divides the left and right sides of the directory window to resize each part of the window

To move the split bar

Using a mouse, drag the split bar. Or choose the Split command from the View menu and use the arrow keys to move the bar.

To cancel the command, press ESC.

Saving Your Setting

If the Save Setting On Exit command is in effect, the positions and views of your open directory windows are retained when you quit File Manager. When you restart File Manager, the open directory windows are in the same position and have the same View menu settings as when you last used File Manager.

To turn the save setting option on or off

From the Options menu, choose Save Settings On Exit. A check mark appears next to the command to indicate it is in effect.

Managing Floppy Disks

You can use commands on the Disk menu to work with floppy disks.

For help on managing your disks, choose one of the following tasks:

Copying a Floppy disk

Formatting a Floppy disk

Labeling a Disk

Making a System Disk

Copying a Floppy Disk

You can copy the contents of one floppy disk to another.

To copy a floppy disk

Insert the source disk in the drive you want to copy from, and if you have two floppy disk drives, insert the destination disk in the drive you want to copy to.

Select the drive Icon for the source disk.

From the Disk menu, choose Copy Disk.

If your computer has two floppy disk drives, the Copy Disk dialog box appears. Select the letter of the destination drive, and then choose the OK button.

Note: If your computer has only one floppy disk drive, the Copy Disk dialog box appears when you need to change disks.

Formatting a Floppy Disk

Before you can use a disk, you must format it. Formatting prepares the disk for use with your computer and deletes any previous information stored on it.

To format a floppy disk

Insert a floppy disk in a drive.

From the Disk menu, choose format Disk.

In the Format Disk dialog box, specify the drive letter, disk capacity, volume label, and other options.

Choose the OK button.

Labeling a Disk

You can assign or change a volume label for a floppy or hard disk.

To assign or change a volume label

If you are labeling a floppy disk, insert it in a floppy disk drive.

Select the drive Icon for the disk you want to label.

From the Disk menu, choose Label Disk.

In the Label Disk dialog box, specify the new label.

Choose the OK button.

Making a System Disk

You can use a system disk to start a computer that runs the MS-DOS operating system. The Make System Disk command copies MS-DOS operating-system files to a formatted floppy disk.

To make a system disk

Insert a formatted floppy disk in a drive.

From the Disk menu, choose Make System Disk.

If your computer has two floppy disk drives, the Make System Disk dialog box appears. Select the letter for the drive that contains the disk, and then choose the OK button.

Note: If your computer has only one floppy disk drive, the dialog box does not appear.

NETWORKING

A group of two or more computer systems linked together. There are many types of computer networks, including:

local-area networks (LANs): The computers are geographically close together (that is, in the same building). wide-area networks (WANs): The computers are farther apart and are connected by telephone lines or radio waves. campus-area networks (CANs): The computers are within a limited geographic area, such as a campus or military base. metropolitan-area networks MANs): A data network designed for a town or city. home-area networks (HANs): A network contained within a user's home that connects a person's digital devices.

In addition to these types, the following characteristics are also used to categorize different types of networks:

topology: The geometric arrangement of a computer system. Common topologies include a bus, star, and ring. protocol: The protocol defines a common set of rules and signals that computers on the network use to communicate. One of the most popular protocols for LANs is called Ethernet. Another popular LAN protocol for PCs is the IBM token-ring network .

What is Ethernet: A local-area network (LAN) architecture developed by Xerox Corporation in cooperation with DEC (Digital Equipment Corporation) and Intel in 1976. Ethernet uses a bus or star topology and supports data transfer rates of 10 Mbps. The Ethernet specification served as the basis for the IEEE 802.3 standard, which specifies the physical and lower software layers. Ethernet uses the CSMA/CD (Carrier Sense Multiple Access / Collision Detection) access method to handle simultaneous demands. It is one of the most widely implemented LAN standards.

architecture: Networks can be broadly classified as using either a peer-to-peer or client/server architecture. Computers on a network are sometimes called nodes. Computers and devices that allocate resources for a network are called servers.

What is peer-to-peer: Often referred to simply as peer-to-peer, or abbreviated P2P, a type of network in which each workstation has equivalent capabilities and responsibilities. This differs from client/server architectures, in which some computers are dedicated to serving the others. Peer-to-peer networks are generally simpler, but they usually do not offer the same performance under heavy loads.

Client/server architecture: A network architecture in which each computer or process on the network is either a client or a server. Servers are powerful computers or processes dedicated to managing disk drives (file servers), printers (print servers), or network traffic (network servers ). Clients are PCs or workstations on which users run applications. Clients rely on servers for resources, such as files, devices, and even processing power.

What is server: A computer or device on a network that manages network resources. For example, a file server is a computer and storage device dedicated to storing files. Any user on the network can store files on the server. A print server is a computer that manages one or more printers, and a network server is a computer that manages network traffic. A database server is a computer system that processes database queries. Servers are often dedicated, meaning that they perform no other tasks besides their server tasks. On multiprocessing operating systems, however, a single computer can execute several programs at once. A server in this case could refer to the program that is managing resources rather than the entire computer.

What is multiprocessing operating systems: (1) Refers to a computer system's ability to support more than one process (program) at the same time. Multiprocessing operating systems enable several programs to run concurrently. UNIX is one of the most widely used multiprocessing systems, but there are many others, including OS/2 for high-end PCs. Multiprocessing systems are much more complicated than single-process systems because the operating system must allocate resources to competing processes in a reasonable manner. (2) Refers to the utilization of multiple CPUs in a single computer system. This is also called parallel processing.

What is node: (1) In networks, a processing location. A node can be a computer or some other device, such as a printer. Every node has a unique network address, sometimes called a Data Link Control (DLC) address or Media Access Control (MAC) address.

What is hub: A common connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports. When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.

A passive hub serves simply as a conduit for the data, enabling it to go from one device (or segment) to another. So-called intelligent hubs include additional features that enables an administrator to monitor the traffic passing through the hub and to configure each port in the hub. Intelligent hubs are also called manageable hubs.

A third type of hub, called a switching hub, actually reads the destination address of each packet and then forwards the packet to the correct port.