Glossary 11
real mode
An operating mode supported by 80286 or higher micro-
processors, real mode imitates the architecture of an
8086 microprocessor. Designed to run in real mode,
MS-DOS (unassisted by additional software techniques)
can address only 640 KB of conventional memory.
refresh rate
The frequency, measured in Hz, at which the screen’s hor-
izontal lines are recharged. A monitor’s refresh rate is also
referred to as its vertical frequency.
REN
Abbreviation for ringer equivalence number.
RFI
Abbreviation for radio frequency interference.
RGB
Abbreviation for red/green/blue.
ROM
Acronym for read-only memory. Your computer contains
some programs essential to its operation in ROM code.
Unlike RAM, a ROM chip retains its contents even after
you turn off your computer. Examples of code in ROM
include the program that initiates your computer’s boot
routine and the POST.
rpm
Abbreviation for revolutions per minute.
RTC
Abbreviation for real-time clock. Battery-powered clock
circuitry inside the computer that keeps the date and time
after you turn off the computer.
SCSI
Acronym for small computer system interface. An I/O bus
interface with faster data transmission rates than standard
ports. You can connect up to seven devices to one SCSI
interface.
SDMS
Abbreviation for SCSI device management system.
sec
Abbreviation for second(s).
serial port
An I/O port used most often to connect a modem or a mouse
to your computer. You can usually identify a serial port on
your computer by its 9-pin connector.
shadowing
A computer’s system and video BIOS code is usually
stored on ROM chips. Shadowing refers to the
performance-enhancement technique that copies BIOS
code to faster RAM chips in the upper memory area
(above 640 KB) during the boot routine.
SIMM
Acronym for single in-line memory module.
SRAM
Abbreviation for static random-access memory. Because
SRAM chips do not require continual refreshing, they are
substantially faster than DRAM chips. SRAM is used
mostly for external cache memory.
SVGA
Abbreviation for super video graphics array. See also
VGA.
switch
See parameter.
syntax
The rules that dictate how you must type a command or
instruction so that the computer will understand it.
system board
As the main circuit board, the system board usually con-
tains most of your computer’s integral components, such
as the following:
•
Microprocessor
•
RAM
•
Expansion-card connectors
•
Controllers for standard peripheral devices, such as
the keyboard
•
Various ROM chips
Frequently used synonyms for system board are mother-
board and logic board.
system diskette
System diskette is a synonym for bootable diskette.
To Next Page
Loading...
