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The Modem, or Modulator-Demodulator, is a device placed between a communicating machine and a telephone line to permit the transmission of digital pulses. A regular phone line is not capable of carrying the digital signals produced by computer-related equipment, having been designed to carry the alternating current of voice type signals (analog signals). The modulator converts the pulses of bits into tones and sends them across the line; the demodulator changes the received tones back into corresponding bits. Most computers are equipped with this type of modem for regular phone lines or a fax modem, which is capable of sending and receiving faxes. Transmission speed is the factor to be concerned with when purchasing a modem. If you possess an older computer you might have a 14.4 Kbps or a 28.8 Kbps modem. What you want is a minimum speed of 56 KBPS or 56000 bits per second of transmission speed.

An internal or external modem can be purchased, but the speed also depends on the quality of the phone line. For example a 56 Kbps modem may not reach that speed if the phone line quality is poor. In some areas of the country cable TV companies are upgrading and providing Internet service over their cable lines. The speed of transmission is much faster using cable lines but you will need a modem that can connect to cable.

Many telephone companies also offers services where a different type of modem is necessary. For example, ISDN (Integrated Services Digital Network) lines or DSL lines are available in certain geographic areas. These lines are capable of faster speeds but they are expensive and are mainly used by business and education customers who are able to pay for the faster speeds.

A monitor displays text and images generated by the video card. A cable connects the monitor to the video card or video adapter, video board, graphics adapter, graphics board, or graphics card, inside the computer case. The size of a monitor is measured diagonally across the screen. Common monitor sizes are 14, 15, 17, and 21 inches. Larger monitors are more expensive and are ideal for desktop publishing and working with graphics or large spreadsheets or for extended periods of time.

The dot pitch is the distance between tiny dots on a screen. The dot pitch determines the sharpness of images on the screen. The smaller the dot pitch, the crisper are the images. If possible select a monitor with a dot pitch of 0.28 mm or less.

The refresh rate determines the speed that a monitor redraws, or updates images. The higher the refresh rate, the fewer flickers are on the screen, this helps to reduce eyestrain. The refresh rate is measured in Hertz (Hz) and tells the number of times per second the monitor redraws the entire screen. A monitor with a refresh rate of 72 Hz or more is recommended.

Monitors have controls to adjust the brightness, contrast and other features of the images displayed on the screen. They also have a tilt and swivel base that lets you adjust the angle of the screen. This lets you reduce the glare from overhead lighting and view the screen more comfortably. Ideally you should be sitting looking slightly down at a screen that is tilted slightly up toward your eyes. A glare filter may be purchased to reduce the amount of light reflected off the monitor to reduce eyestrain.

A multisync monitor lets you adjust the resolution of the monitor to suit your needs. The amounts of horizontal and vertical pixels are measures of resolution. A pixel (from picture element) is the smallest element on the screen. Lower resolutions display larger images so you can see information more clearly, for example, 640 x 480. Higher resolutions display smaller images so you can display more information at once such as 1280 x 1024.

The number of colors a monitor can display determines how realistic images appear on a screen. More colors result in more realistic images. Visually, a 256 Colors (8-bit color) monitor is adequate for most home, business and game applications. Ideal for video and desktop publishing applications is the 16-bit color monitor that produces 65,536 colors. The next highest setting for color is sometimes called true color in your Control Panels settings for Monitor Display, because it displays more colors than the human eye can distinguish. But for the trained professional it is difficult to distinguish between 16-bit color and true color, which is 24-bit color and has 16,777,216 colors. Unless you are doing photographic work you do not need to set the display this high.

There are many factors to consider when deciding on a printer as they can do many different things. They can print on many different mediums, in color or black and white, at different speeds, with different qualities of print. It is highly suggested you do a bit of research and assess your needs before purchasing a printer.

• Things to keep in mind to begin your research are printer speed, (measured in characters per second (cps) or pages per minute (ppm). A complicated page, such as a page with graphics or spreadsheets takes longer to print than a page that contains only text.

• A higher resolution results in sharper more detailed pictures, but also slows speed. Printer resolution is measured in dots per inch (dpi). Generally a resolution of 300 dpi is acceptable for most office documents, although if you want better graphics or photo quality 1200 dpi is becoming standard.

• An inkjet printer can be black and white or color and are very popular because they are less expensive than color laser printers and still produce high-quality color images. The best color images come from inkjet printers that offer black as a separate color, (as some color printers create black by mixing the cyan, magenta, and yellow ink). Ink comes in cartridges and you will have to purchase both kinds for these printers. The ink-jet also accepts more mediums than the dot matrix printer but make sure you purchase mediums designed specifically for the ink-jet to achieve the best results; these mediums also come in different qualities.

• A laser printer produces documents faster and with superior quality images. Like photocopiers, laser printers use fine powdered ink, called toner, which comes in a cartridge. There are multifunction laser printers available that can perform more than one task. They are able to work as a fax machine, scanner, and photocopier as well as a printer. Laser printers store pages in built-in memory before printing.

There are other types of printers available as well including solid ink, thermal wax, and dye sublimation, which is the most expensive type. Please take into account all the variables before purchasing a printer. Remember this machine represents more than the initial cost. Keep in mind the cost of supplies for the machine, ease of use, and how many uses you will put it to. You can achieve a high quality product without purchasing the most expensive printer.

A scanner is a device that reads graphics and text into a computer. Most scanners come with image editing software, which lets you change the appearance of a scanned graphic. Scanners come in grayscale, (which reads images using black and white, and shades of gray) and color and like printers differ in resolution capability. Scanning an image at a high resolution results in a clearer, more detailed image, but requires more scanning time and storage space. You usually do not need to scan an image at a higher resolution than your printer can produce or a monitor can display. If you plan to print an image on a 300 dpi printer, you generally do not need to scan at a resolution higher than 300 dpi.

Scanners also come in different types. The hand held scanner is the least expensive but has a scanning width of approximately four inches. This is ideal if you are only copying small images, such as signatures, business cards, logos and small photographs. A sheet-fed scanner produces more reliable scans than a hand-held scanner and is less expensive and more compact than a flatbed scanner, but can only scan single sheets of paper. If you want to scan a page from a book, you have to tear out the page. A flatbed scanner is the most expensive and the most versatile. It is ideal if you wish to scan pages from a book without tearing out the pages.

The scanner may also be used similar to a copy machine, in that you scan a document, such as a letter received, into the computer and then can fax or email the document elsewhere.

The hard drive is the primary device that a computer uses to store information and is also called the hard disk, hard disk drive or fixed disk drive. Most computers have one hard drive located inside the computer case and designated as drive "C". The hard drive magnetically stores data on a stack of rotating disks called platters and has several read/write heads that read and record data on the disks. A hard drive stores your programs and data files, such as documents, spreadsheets, and graphics.

When you buy a new program, you must install, or copy the program files, usually from a CD-ROM disk or several floppy disks, to your hard drive before you can use the program. When you are creating a document, the computer stores the document in temporary memory. If you want to store a document for future use, you must save the document to the hard drive. If you do not save the document, the document can be lost if there is a power failure or when you turn off the computer. It is important to save your work every so often or when getting up from the computer for a bit. It is frustrating to lose a few hours work when you do not have to, or if the computer locks up you can lose all that you have done instantly.

Hard drives for the Personal Computer are measured by the amount of information they can store; and are currently measured in Gigabytes. See GLOSSARY. Advantages of the hard drive are,

• it is inside the computer
• is easily accessible
• is very organized
• has the capacity for large storage jobs.

Some of the disadvantages are:

• you can’t access a file on it, from anywhere but the computer itself
• or transfer one to a friend or colleague unless you are at your computer
• if the only copy of your work is on the hard drive you may be in danger of losing all your files if it crashes!

A floppy drive stores and retrieves information on floppy disks, usually a 3.5-inch thin plastic, flexible disk that magnetically records information. You can increase the available space on your computer by copying old or rarely used files to floppy disks. You then can remove the files from the computer’s hard drive thereby freeing up space. You can also use floppy disks to transfer data from one computer to another. This type of storage allows you to share data and colleagues.

One of the advantages of a floppy disk is every computer has a floppy disk drive built in and can read data from a disk written on any other computer. The floppy disks can also serve as backup copies of files if the hard drive fails or you accidentally erase a file. The floppy disk can be written to and then write-protected (by sliding a little tab on the disk) so information cannot be erased accidentally. Information can be erased and new information recorded by reformatting the disk.

The disadvantage of using floppy disks, as a backup system is the amount of information they hold is very small, (1.44 MB) and you would need many of them just to contain all your basic program information in case of failure. They can also be easily lost or damaged if you are not careful.

The floppy drive is usually designated drive "A" and the disk can be formatted or reformatted, (most disks sold today are preformatted ready to write to when you buy them). You can format a disk by double clicking on My Computer, selecting drive "A", clicking on File, then selecting format and following the dialog boxes directions.

Jaz and Zip are two different types of drives. A Jaz drive can store up to 1 GB (1000 MB) of data whereas a Zip drive can store 100 MB of data. You can remove files from your hard drive to provide more storage capacity. They also can be used to backup your systems information in case of a hard drive failure, then you can recover what was stored on your computer.

When using Jaz or Zip disks there is a tradeoff. While they hold large amounts of data, if you wish to transfer the information to another computer that CPU has to have a Zip or Jaz drive and many do not.

Jaz drives are manufactured by the Iomega Corporation http://www.iomega.com/ for help and support. Zip drives are manufactured by several companies, although Iomega was the first company to do so and is the most common manufacturer if your drive was pre-installed on the computer.

Most CD-ROM drives are located inside the computer case although external ones can be purchased. A CD-ROM drive is a device that reads information stored on compact discs. The initials stand for Compact Disc-Read Only Memory, which means you cannot write to the disc to add to or change the information stored on it. The advantages of a Compact Disc are its large capacity to hold multimedia data, more than 600 MB, which is equal to a whole set of encyclopedias or over 400 floppy disks. The easy portability of the CD disc and the accessibility of a CD-ROM drive on many computer systems. The CD drive is usually designated with the letter "D" and can be utilized at the same time as the hard disk drive enabling you to play a music CD while working on the computer.

There are thousands of educational and entertaining CD-ROM discs available. Most CD-ROM titles are interactive. You can move through topics covered on a disc at your own pace and play games or find topics of interest in seconds. Some CD-ROM titles, such as Microsoft Encarta, let you access updated information on the Internet. HINT: Floppy disks are spelled with a "k" and compact discs are spelled with a "c".

The speed of a CD-ROM drive determines how fast a disc spins. With faster speeds, information can transfer from a disc to the computer more quickly, which results in better performance. Speed is very important when viewing video and animation often found in games and encyclopedias. Slow speeds will result in jerky performance. Each x in the speed is equal to 150 Kbps transfer, which means that a drive that is listed as 4x can spin the disc and transfer data at 600 Kilobits per second and one listed as 8x will transfer the data at 1200 Kilobits per second. The slower speeds are perfectly adequate for the older CDs and music CDs but for the latest games with their animation and multimedia presentations the faster the drive the better the performance.

Information can be stored on a disc at separate times called sessions, for example you can have a photo-finisher record slides on a disc with a device called a CD burner and then add more slides to the disc later. The CD burner is also called CD-RW or Compact Disc-Read and Write.

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