Specifications

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Appendix A Glossary
file A collection of information kept somewhere
other than in random-access memory.
file attribute Information held in the attribute
byte of a file’s directory entry.
file compression See compressed file.
filename The name given to the disk file. For
DOS, it must be from one to eight characters long
and can be followed by a filename extension,
which can be from one to three characters long.
Windows 9x and above ease these constraints by
allowing filenames of up to 255 characters, includ-
ing the directory path.
firewall A hardware or software system designed
to prevent unauthorized access to or from a private
network.
FireWire Also called IEEE 1394 or i.Link. A serial
I/O interface standard that is extremely fast, with
data transfer rates up to 400MBps, 800MBps, or
3.2GBps, depending on the version of standard
used. Most current implementations use the
400MBps IEEE 1394a version.
firmware Software contained in a read-only
memory (ROM) device. A cross between hardware
and software, firmware can be easily updated if
stored in an EEPROM or flash ROM chip. See also
EEPROM and flash ROM.
fixed disk Also called a hard disk, it’s a disk that
can’t be removed from its controlling hardware or
housing. Made of rigid material with a magnetic
coating and used for the mass storage and retrieval
of data.
flash ROM A type of EEPROM developed by
Intel that can be erased and reprogrammed in the
host system. See also EEPROM.
flat panel display (FPD) A type of display that
is thinner and lighter than traditional CRTs, usually
based on LCD, plasma, or LED technology.
flicker A monitor condition caused by refresh
rates that are too low, in which the display flashes
visibly. This can cause eyestrain or more severe
physical problems.
floating-point unit (FPU) Sometimes called
the math coprocessor; handles the more complex
calculations of the processing cycle.
floppy disk A removable disk using flexible
magnetic media enclosed in a semirigid or rigid
plastic case.
floppy disk drive (FDD) A type of magnetic
media storage where data is stored on flexible
mylar disks with a magnetic coating. A popular
form of storage used by personal computers during
the 80s and 90s.
floppy disk controller The logic and interface
that connects a floppy disk drive to the system.
floppy tape A tape standard that uses drives
connecting to an ordinary floppy disk controller,
such as QIC-80 or Travan-1.
floptical drive A special type of high-capacity
removable disk drive that uses an optical mecha-
nism to properly position the drive read/write
heads over the data tracks on the disk. This enables
more precise control of the read/write positioning
and thus narrower track spacing and more data
packed into a smaller area than traditional floppy
disks. The LS-120 and LS-240 SuperDisk drives are
recent examples of floptical drives.
flow control A mechanism that compensates
for differences in the flow of data input to and out-
put from a modem or other device.
FM encoding Frequency modulation encoding.
An outdated method of encoding data on the disk
surface that uses up half the disk space with timing
signals.
FM synthesis An audio technology that uses one
sine wave operator to modify another and create an
artificial sound that mimics an instrument.
folder In a graphical user interface, a simulated
file folder that holds documents (text, data, or
graphics), applications, and other folders. A folder
is similar to a DOS subdirectory.
footprint Describes the shape of something. See
also form factor.
form factor The physical dimensions of a
device. Two devices with the same form factor are
physically interchangeable. The IBM PC, XT, and
XT Model 286, for example, all use power supplies
that are internally different but have exactly the
same form factor.
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