sketches, or selecting items from menus on a screen.
When the mouse is rolled across the surface of the desk,
the cursor moves a corresponding distance on the
routines for detection and correction of data errors. A
CD-ROM drive may be internally or externally
installed. It holds a vast amount of information that
makes it valuable to store digital images. Once
recorded, information on CD-ROM cannot be erased or
changed, but it can be read many times. The expression
information. Data is recorded sequentially in the form
of magnetic spots along the entire length of the tape.
surfaces of rotating disks. The disks are made of thin
metal, coated on each side so data can be recorded in
the form of magnetized spots. As the disks spin around
like a music record, characters can be stored on them or
retrieved from them in a random (direct) manner.
Accessing data directly has several advantages over
accessing data stored sequentially. It provides fast
disk drive to read at any point. Magnetic disk drives
come in two types: hard drives and floppy drives.
Magnetic disk drives are in computer systems and
electronic cameras. Floppy disks come in several sizes,
ranging from 3 to 8 inches in diameter; the 3 1/2-inch
diskette is most common.
lower-power laser pickup. Three types of optical disks
are used: Read Only (RO), Write Once, Read Many
(WORM), and erasable. Two types of erasable disks are
used: Thermo Magneto Optical (TMO) and Phase
photographs on hardcopy (paper or film). A large range
of printers is available. Printers are discussed in more
detail later in this chapter.
devices. This is accomplished by electrical cables that
carry both data and control information between the
computer and the peripheral devices.
cable provides a path (channel) for the signal to travel.
Signals for both monitoring and data are transmitted by
way of I/O channels. These I/O channels may be used
specifically for data input, data output, or data input and
output. On desktop computers, the I/O channels are
referred to as communication ports.
of communication in one direction. When a peripheral
circuit, it is only capable of transmitting data. Simplex
circuits are seldom used because a return path is
generally required for acknowledgment, control
information, or error message.
is for receiving data.
Advanced Photography Course