Microsoft Office Tutorials and References
In Depth Information
Data Communications
example, recordable DVDs are available as DVD-R and DVD+R. Make sure you know
which type of DVD your DVD drive uses. The computer shown in Figure 1 includes a 4x
recordable/rewritable DVD drive. It supports both the -RW and +RW formats, and it can
read and record CDs as well.
Another alternative to magnetic storage are flash memory storage devices . Small and
portable, flash memory stores data on a silicon chip (normally encased in hard plastic)
and does not need power to maintain the information. Commonly used for storing data
for cell phones, digital cameras, and PDAs, (under the brand names CompactFlash,
SmartMedia and Memory Stick) flash memory storage devices are growing in popularity
as secondary or backup storage devices for data typically stored on a hard disk drive.
These storage devices plug directly into the USB port of a personal computer, where your
computer recognizes it as another disk drive. With no moving parts, flash memory storage
devices can even be attached to a keychain! Flash storage devices for personal computers
can hold up to 512 MB of data, well exceeding the amount of data that can be stored on
a floppy disk. The computer shown in Figure 1 has six USB ports.
Figure 22 shows the typical storage configuration of a personal computer. It includes a
DVD±RW drive, a floppy disk drive, and a hard drive.
Figure 22
Typical personal computer storage configuration
3 1 / 2 " disk
light for
hard drive
You decide that your recommendation to Mr. Paik should include computers with at
least CD-RW drives, and some computers with DVD±RW drives. As computers are used,
the storage devices fill up quickly with software and data, so it’s a good idea to purchase
as much storage capacity as your budget allows. Even though floppy disks are becoming
less popular as recordable CD and DVD drives drop in price and flash memory storage
devices become more readily available, Mr. Paik still has plenty of data stored on floppy
disks, so you will recommend floppy disk drives as well. You also decide to recommend at
least 80 GB hard drives and perhaps 120 GB hard drives for some of the machines. You
will also recommend at least 512 MB of RAM for each machine.
Data Communications
The transmission of text, numeric, voice, or video data from one computer to another is
called data communications . This broad-based definition encompasses many critical busi-
ness activities, from sending a letter to the printer upstairs to sending an e-mail ( electronic
mail ) message to the company offices around the globe.
The four essential components of data communications are a sender, a receiver, a
channel, and a protocol. The computer that originates the message is the sender . The mes-
sage is sent over some type of channel , such as telephone or coaxial cable, a microwave
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