Specifications

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Appendix A Glossary
Also refers to the ATA interface standard—the stan-
dard for attaching hard disk drives to ISA bus IBM-
compatible computers. IDE drives typically operate
as though they are standard ST-506/412 drives. See
also ATA.
IEEE 802.3 See 10BASE-2.
IEEE 802.11 family A family of wireless net-
work standards commonly known as wireless
Ethernet, the most popular of which include
802.11a (54Mbps using 5GHz signaling), 802.11b
(11Mbps using 2.4GHz signaling), 802.11g (54Mbps
using 2.4GHz signaling), and 802.11n (540Mbps
using 2.4GHz or 5GHz signaling). See also Wi-Fi.
IEEE 1284 A series of standards for parallel ports.
IEEE 1284 includes EPP and ECP configurations as
well as the older bidirectional and 4-bit compatible
parallel port modes. Printer cables that can work
with all modes are referred to as IEEE 1284–
compliant cables. See also EPP and ECP.
IEEE 1394 See FireWire.
illegal operation A command sent to Windows
or the processor that can’t be performed. Illegal
operations can be triggered by software bugs or
conflicts between programs in memory; although
the name is reminiscent of a penalty in football, an
illegal operation is hardly ever caused by the com-
puter user. In most cases, you can continue to work
and might even be able to restart the program
without rebooting.
impedance The total opposition a circuit offers
to the flow of alternating current, measured in
ohms.
incremental backup A backup of all the files
that have changed since the last backup.
inductive A property in which energy can be
transferred from one device to another via the mag-
netic field generated by the device, even though no
direct electrical connection is established between
the two.
.INF file A Windows driver and device informa-
tion file used to install new drivers or services.
Information Technology (IT) Involves the
managing and processing of information, especially
in a company or organization.
ingot See boule.
initiator A device attached to the SCSI bus that
sends a command to another device (the target) on
the SCSI bus. The SCSI host adapter plugged into
the system bus is an example of a SCSI initiator.
inkjet printer A type of printer that sprays one
or more colors of ink on the paper; it can produce
output with quality approaching that of a laser
printer at a lower cost.
input Data sent to the computer from the key-
board, the telephone, a video camera, another com-
puter, paddles, joysticks, and so on.
InstallShield A popular program used to create
installation and uninstallation routines for
Windows-based programs.
instruction A program step that tells the com-
puter what to do for a single operation.
integrated circuit See IC.
interface A communications device or protocol
that enables one device to communicate with
another. Matches the output of one device to the
input of the other device.
interlacing A method of scanning alternate
lines of pixels on a display screen. The odd lines are
scanned first from top to bottom and left to right.
The electron gun goes back to the top and makes a
second pass, scanning the even lines. Interlacing
requires two scan passes to construct a single
image. Because of this additional scanning, inter-
laced screens often seem to flicker unless a long-
persistence phosphor is used in the display.
Interlaced monitors were used with the IBM 8514/A
display card but are now obsolete for desktop
computers.
interleave ratio The number of sectors that
pass beneath the read/write heads before the “next”
numbered sector arrives. When the interleave ratio
is 3:1, for example, a sector is read, two pass by,
and then the next is read. A proper interleave ratio,
laid down during low-level formatting, enables the
disk to transfer information without excessive revo-
lutions due to missed sectors. All modern IDE and
SCSI drives have a 1:1 interleave ratio.
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