| RAID |
(Redundant Array of Inexpensive Disks)
-is a technology that spreads data across a group or groups
of disk modules. Using parallel redundant disk drives RAID,
properly implemented, allows an application to remain online
and ride through disk failure. Repair takes place under power
and data is automatically restored thru parity. There are seven
RAID implementations defined. |
|
Level O -disk array with stripping
but no parity protection {therefore not considered "true
RAID" |
|
Level 1 -mirrored disk array with
duplicated data |
|
Level 2 - disk array with bit-Ievel
striping and parity on three disk in the array |
|
Level 3 - disk array with byte-interleaved
data and parity on one disk |
|
Level 4 - disk array with block-interleaved
data and parity on one disk |
|
Level 5 -disk array with block-interleaved
data and distributed parity across all drives |
|
Level
10 - disk array with block striping at the operating system
level and mirroring at the disk target controller level. |
| RAM |
stands for Random Access Memory.
It's the computer's internal memory, measured in K. RAM is
like a desktop: the more items you can keep handy at once. Turning
off the computer is like clearing off your desk, because whatever
was in the machine's RAM is lost unless it's first saved to
disk. |
| Raster |
a
horizontal scan line on a screen. TV and computer screens work
by painting a series of raster lines that change rapidly to
convey the sense of moving pictures or text. |
| Real time |
the
actual time during which something takes place, or in the case
of a computer, responding to signals as they come in. An image
processing device is said to work in real time when it responds
to changes in the fine data file instantly during an operator's
manipulations rather than processing the changes at a later
time. |
| Resolution |
sharpness, in either a screen or
printout. A resolution of about 72 dots per (square) inch is
a common resolution of computer monitors and inexpensive dot
matrix printers; The higher the resolution, the finer the image
quality. Good laser or inkjet printers and scanners provide
a resolution of 600 dots per inch; high-quality typesetting
machines can print at 2,540 dpi. |
| RISC |
(Reduced Instruction Set Computing)
-A chip architecture characterized by a regular and uncomplicated
set which simplifies, hardware design, allowing fast, highly-pipelined
implementations. Because of this simplicity , the instruction
execution rate of a RISC machine is faster that that of a CISC
machine. (See CISC) |
| ROM |
stands
for Read Only Memory .ROM is memory in a computer that is permanently
encased in a chip. ROM is not erased when the power is turned
off. |
| Router |
A device that finds the best path
for a data packet to be sent from one network to another. A
router stores and forwards electronic messages between networks,
first determining all possible paths to the destination address
and then picking the most expedient route, based on the traffic
load and the number of hops.A router works at the network layer
(layer 3 of the OSI model); a bridge works at the data link
layer (layer 2).A router does more processing than a bridge
does. A router can be hardware or a combination of hardware
and software. |
| Runaround |
in typesetting, text
that flows around a graphic. |
| Scanner |
An input device that reads images
or text and converts the data into digital signals.Graphical
scanners read photos or other images into the computer and digitize
them, producing bitmapped graphics files.Text scanners use optical
character recognition software to read pages of text and produce
editable text files.Bar code scanners, as used in stores, convert
bar codes into digital information. Some types of scanners
are flatbed scanners, sheet-fed scanners, hand-held scanners,
and slide scanners. |
| SCSI |
Small Computer Systems Interface.(Pronounced
"scuzzy".) A high-speed interface that can connect
to a computer devices such as hard drives, CD-ROM drives, floppy
drives, tape drives, scanners, and printers. It was developed
by Shugart Associates (now called Seagate).SCSI is An ANSl-standard
bus interface that provides daisy-chaining which can connect
up to seven devices; each one is given an identification number
from 0 to 7, which is set with a manual switch. Newer versions
of SCSI can connect up to 15 devices.The SCSI cable transfers
eight bits at a time, in parallel. |
| Serial |
a type of connector from the computer
to the outer world, used by most modems and some
printers. |
| Slots |
spaces
inside a computer where extra circuit boards can be inserted
to extend the function of the machine. The current Mac and PC
families of microcomputers each have multiple slots. |
| Software |
the
abstract parts of a computer system, the programs that make
it actually accomplish anything. |
| SPARC |
The
name of the RISC chipset used by and licensed by Sun Microsystems.
|
| Style sheet |
a
series of typographic formats stored so they can be quickly
applied to repeating text, which is easier than manually formatting
large sections. |
| System architecture |
the
configuration of components, consoles, peripherals and connections
that make up a total system. |
| TCP/IP |
(Transmission
Control Protocol/Internet Protocol)- These are two specific
protocols in the family of protocols originally developed to
implement the ARPANET wide area network by the US Dept. of Defence(DARPA).
These protocols were developed by DARPA to enable communication
between different types of computers and computer networks.The
Internet Protocol is a connectionless protocol which provides
packet routing.TCP is connection-oriented and provides reliable
communication and multiplexing. Usually, the term TCP/IP is
used to refer to the entire suite of protocols which includes
IP and TCP, among others. Partly because TCP/IP was published
early in the evolution of local area networks, and partly because
of its widespread distribution with BSD UNIX, it has become
a de facto standard for communication between dissimilar machines.
|
| Tele-communications |
using
your computer to talk to other computers some distance away,
most often through the telephone lines using a modem. |
| Terabyte |
one
trillion bytes. |
| Terminal |
a
computer screen and keyboard often connected to a large computer
system. May be called a "dumb terminal" if it relies
on the larger computer for all its processing. |
| TIFF |
stands
for Tagged Image File Format. A standard file format usually
used for scanned graphic images. |
