Specifications

Glossary
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REV A proprietary hard-disk-based removable-
media drive made by Iomega. REV has a native/
2.6:1 compressed capacity of 35/90GB per cartridge.
REV can be used for backup or primary storage. An
autoloader is also available. See also autoloader.
revolutions per minute (RPM) A measure-
ment of rotational speed.
reverse engineering The act of duplicating a
hardware or software component by studying the
functions of the component and designing a differ-
ent one that has the same functions.
RFI (radio frequency interference) A high-
frequency signal radiated by improperly shielded
conductors, particularly when signal path lengths
are comparable to or longer than the signal wave-
lengths. The FCC now regulates RFI in computer
equipment sold in the U.S. under FCC Regulations,
Part 15, Subpart J.
RGB (red green blue) A type of computer color
display output signal composed of separately con-
trollable red, green, and blue signals, as opposed to
composite video, in which signals are combined
prior to output. RGB monitors offer much higher
resolution and sharper pictures than composite
monitors.
ribbon cable Flat cable with wires running in
parallel, such as those used for internal IDE or SCSI.
Rich Text Format (RTF) A universal file for-
mat suitable for exchanging formatted text files
between different word processing and page layout
programs.
RIMM (Rambus inline memory module) A
type of memory module made using RDRAM chips.
See also RDRAM.
RISC (reduced instruction set computer)
Differentiated from CISC, the complex instruction
set computer. RISC processors have simple instruc-
tion sets requiring only one or a few execution
cycles. These simple instructions can be used more
effectively than CISC systems with appropriately
designed software, resulting in faster operations.
See also CISC.
RJ-11 The standard two-wire connector type used
for single-line telephone connections.
RJ-14 The standard four-wire connector type
used for two-line telephone connections.
RJ-45 An informal designation used to describe
the 8P8C (8-pin, 8-conductor) standard connector
type used in networking with twisted-pair cabling.
Resembles an RJ-11/14 telephone jack, but RJ-45 is
larger with more wires.
RLL (run-length limited) A type of encoding
that derives its name from the fact that the tech-
niques used limit the distance (run length) between
magnetic flux reversals on the disk platter. Several
types of RLL encoding techniques exist, although
only two are commonly used. (1,7) RLL encoding
increases storage capacity by about 30% over MFM
encoding and is most popular in the very highest
capacity drives due to a better window margin,
whereas (2,7) RLL encoding increases storage capac-
ity by 50% over MFM encoding and is used in the
majority of RLL implementations. Most IDE, ESDI,
and SCSI hard disks use one of these forms of RLL
encoding.
RMA number (return-merchandise autho-
rization number) A number given to you by a
vendor when you arrange to return an item for
repairs. Used to track the item and the repair.
ROM (read-only memory) A type of memory
that has values permanently or semipermanently
burned in. These locations are used to hold impor-
tant programs or data that must be available to the
computer when the power initially is turned on.
ROM BIOS (read-only memory basic
input/output system) A BIOS encoded in a
form of read-only memory for protection.
root directory The main directory of any hard
or floppy disk. It has a fixed size and location for a
particular disk volume and can’t be resized dynami-
cally the way subdirectories can.
router A device that is used to connect various
networks, intelligently routing information
between them. It is used to internetwork similar
and dissimilar networks and can select the most
expedient route based on traffic load, line speeds,
costs, and network failures. Routers use forwarding
tables to determine which packets should be for-
warded between the connected networks. A cable
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