Modem

A contraction of "Modulator - demodulator", a modem allows a computer to communicate over an analogue medium (most commonly a telephone line). The modem encodes digital signals from the computer as analogue signals suitable for transmission (modulation) and decodes digital data from a modulated analogue signal (demodulation). Using modems two computers may communicate over a telephone line, with the data passed between them being represented as sound.

Modems are usually involved with dial-up internet services. As broadband catches on, they are falling into disuse. However, the devices used to connect to broadband connections are also called modems, specifically DSL Modems or Cable Modems.

Printer

A printer makes marks on paper. It can print images and text.

The most common types of printers today are

• Laser printer: Prints very crisp text, but cheaper models can only print in black and white. Good for places like offices where high printing speed is needed.
• Color inkjet printer: Prints photos and other images in color (using 4 colors of ink -- cyan, magenta, yellow, and black), but the text they print is often not as crisp as a laser printer.
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The average printer of the early 1990s would connect to a computer through its parallel port. To connect it to the computer via parallel port, one would have to screw it into the port. Today many printers are connected through USB. This is because it is easier to connect and remove through a simple plug and play system. It also allows for faster transfer speeds than parallel.

USB Flash drive

Memory sticks or Flash drives are solid-state NAND flash chips packaged to provide additional memory storage. 

These drives are quickly replacing floppy disks as a means of transferring data from one PC to another in the absence of a network.

Flash memory

Some common types of Flash memory cards are CompactFlash, Secure Digital (SD), and xD. There are other formats which are falling into disuse, such as Smartmedia (SM) and MultiMediaCard (MMC).

Flash memory is faster than magnetic media and much more rugged. The main reason Flash hasn't yet replaced hard drives is that Flash memory is much more expensive per gigabyte than hard drives.

DVD-RW drive

DVD's hold about 4.7 gigabytes and dual-layer disks hold 8.4 gigabytes (dual layer equipment and disks are now becoming more affordable)

DVD-ROM drive

Digital Video/Versatile Disk Read Only Memory (DVD-ROM)

This optical drive works on a similar principle to the CD-ROM, with a laser being used to read data stored in pits on the surface of a reflective disk. DVDs are read using a shorter wavelength of light (a red laser, rather than an infra-red one). In addition to having a greater data-density, DVDs may be double sided and may be "dual layer".

cd-rw drive speeds

Compact disc Read/Write drives support the creation of CD-R and CD-RW discs, and also function as CD-ROM drives. These drives use low-powered lasers to 'burn' data into the active layer of the disc.

CD-R (Compact disc recordable) discs are 'write once' - once they have been written to, the data cannot be erased or changed. However, multisessions can be created and more data can be added.

CD-RW (Compact disc rewritable) discs can be rewritten or erased multiple times. This is a two-pass process so they typically take twice as long as CD-R discs to produce.

CD-RW drives will typically have three speed ratings - one for reading discs, one for writing CD-R discs and another for writing CD-RW discs. Speed ratings vary from 1x to 52x, where 1x means that a CD is written/read in 'real time' - a 52 minute audio CD would take about 52 minutes to create at 1x speed, and about 1 minute at 52x speed.

The data can be written to the disc in a variety of formats to create an audio CD, a data CD, a video CD or a photo CD. The audio CDs should play on most standard audio CD equipment and the video and photo CDs will play on many consumer DVD players.

Many CD writers (also known as 'burners') are now combination drives which also function as DVD-ROM drives.

Most DVD-RW drives also have CD-RW capabilities.

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