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RAID :
Redundant Array of Inexpensive Disks. A method of mirroring or
striping data on clusters of low-end disk drives; data is
copied onto multiple drives for faster throughput, error
correction, fault tolerance and improved mean time between
failures.
RAM :
Random Access Memory. Part of storage containing the programs
being executed. This technology generally requires regular
refresh of the data, hundreds or thousands of times per second
(in case of Dynamic RAM which is most frequent). Thus, the
data are lost when the system is switched to power-off state.
RAM disk :
Part of main storage used as a disk unit. Reading and writing
being much faster in storage than on disk, RAM disk files
speed up the program execution.
RDF :
(Resource Definition Framework) A set of rules (a sort of
language) for creating descriptions of information, especially
information available on the World Wide Web. RDF could
be used to describe a collection of books, or artists, or a
collection of web pages as in the RSS data
format which uses RDF to create machine-readable summaries of
web sites.
RDF is also
used in XPFE applications to define the relationships
between different collections of elements, for example RDF
could be used to define the relationship between the data in a
database and the way that data is displayed to a user.
Real mode :
For Intel microprocessors, production mode used to address the
first storage MB. In real mode, the memory address used by the
application is equal to the physical address in storage.
Refresh :
Regular rewrite allowing to maintain displayed data on a
screen or data in RAM storage.
Removable hard disk :
Hard disk that can be removed from a laptop computer. This
type of unit generates a special risk in terms of security.
Removable storage units :
Magnetic tape, disk or cartridge on which are recorded data.
Removable units are most frequently used to create safety
copies of hard disk data.
Repeater :
A hardware device that adapts two wires or fibers to each
other. It also amplifies the data before passing it to another
medium. A repeater connects networks at OSI Layer 1.
Response Time :
The time period between a terminal operator's completion of an
inquiry and the receipt of a response. Response time includes
the time taken to transmit the inquiry, process it by the
computer, and transmit the response back to the terminal.
Response time is frequently used as a measure of the
performance of an interactive system.
Resolution :
It defines the thinness of restitution of information provided
by an output device such as a screen or a printer. It is
usually measured in number of points. On screens, in 1995, the
most frequent resolutions are 640 points per row and 480
points per column (called VGA), 800x600 (called SVGA) and
1024x768. On printers, it is measured in number of points per
inch. On laser printers, in 1995, it is most frequently 300 or
600 points per inch. We can observe that resolution is much
higher on printers than on screens.
RFC :
(Request For Comments) The name of the result and the process
for creating a standard on the Internet. New standards
are proposed and published on the Internet, as a Request For
Comments. The proposal is reviewed by the Internet Engineering
Task Force (http://www.ietf.org/), a consensus-building body
that facilitates discussion, and eventually a new standard is
established, but the reference number/name for the standard
retains the acronym RFC, e.g. the official standard for
e-mail message formats is RFC 822.
RGB :
Red Green Blue. Colored components used for color display
screens.
RISC :
Reduced Instruction Set Computer. An architecture that shifts
the analytical process of a computational task from the
execution or run time to the preparation or compile time. By
using less hardware or logic, the system can operate at higher
speeds. A processor architecture that cuts down on the number
and complexity of instructions, on the theory that each one
can be accessed and executed faster, and that less
semiconductor circuitry is required to process them. The
result is that for any given semiconductor technology, a more
powerful microprocessor can be produced with RISC than with
CISC (complex instruction set computer) architectures.
However, the compilers role becomes critical, and the
effective throughput of the system will heavily depend on
them.
RJ11 :
Standard jacket for telephone line interface.
RJ45 :
Standard interface type between computers and
LANs, using UTP cables.
RNIS :
"Raseau Numurique Integration de Services". French name for
ISDN. The commercially available service proposed by the
national operator, France Telecom, is named "Numbers".
ROM :
Read-Only Memory. Storage unit which retains data even when
the computer is powered off. This storage cannot be modified
by the user.
Router :
Performs a function similar to a local or remote bridge, but
routing occurs at Layer 3 of the Open Systems Interconnection
reference model.
A special-purpose computer (or software package) that handles
the connection between 2 or more Packet-Switched networks.
Routers spend all their time looking at the source and
destination addresses of the packets passing through
them and deciding which route to send them on.
Routine :
Part of a program responsible for a complete function. A
program composed of a number of distinct but linked routines
is called "modular".
RPC :
Remote Procedure Call. A mechanism that extends the notion of
a local (i.e., contained in a single address space) procedure
call to a distributed computing environment, enabling an
application to be distributed among multiple systems in a way
that is highly transparent to the application-level code.
Examples of RPCs are Apollo's Network Computing System., Sun
Microsystems's Open Network Computing, Sybase's Open
Client/Open Server and the Open Software Foundation's
Distributed Computing Environment RPC.
RS-232-C :
A technical specification published by the Electronic
Industries Association that establishes mechanical and
electrical interface requirements between computers, terminals
and communications lines.
RSS :
(Rich Site Summary or RDF Site Summary or Real Simple
Syndication) A commonly used protocol for syndication and
sharing of content, originally developed to facilitate the
syndication of news articles, now widely used to share the
contents of blogs.
RSS is an XML-based summary of a web site, usually used
for syndication and other kinds of content-sharing.
There are RSS "feeds" which are sources of RSS information
about web sites, and RSS "readers" which read RSS feeds and
display their content to users.
RSS is being overtaken by a newer, more complex protocol
called Atom. |
