Java Reference
In-Depth Information
There are three main types of storage devices:
Magnetic disk drives
■
Optical disc drives (CD and DVD)
■
USB flash drives
■
Drives
are devices for operating a medium, such as disks and CDs. A storage medium
physically stores data and program instructions. The drive reads data from the medium and
writes data onto the medium.
Disks
A computer usually has at least one hard disk drive (Figure 1.4).
Hard disks
are used for per-
manently storing data and programs. Newer computers have hard disks that can store from
200 to 800 gigabytes of data. Hard disk drives are usually encased inside the computer, but
removable hard disks are also available.
drive
hard disk
F
IGURE
1.4
A hard disk is a device for permanently storing programs and data.
CDs and DVDs
CD
stands for compact disc. There are two types of CD drives: CD-R and CD-RW. A
CD-R
is
for read-only permanent storage; the user cannot modify its contents once they are recorded.
A
CD-RW
can be used like a hard disk; that is, you can write data onto the disc, and then over-
write that data with new data. A single CD can hold up to 700 MB. Most new PCs are
equipped with a CD-RW drive that can work with both CD-R and CD-RW discs.
DVD
stands for digital versatile disc or digital video disc. DVDs and CDs look alike, and
you can use either to store data. A DVD can hold more information than a CD; a standard
DVD's storage capacity is 4.7 GB. Like CDs, there are two types of DVDs: DVD-R (read-
only) and DVD-RW (rewritable).
CD-R
CD-RW
DVD
