Users Guide

Glossary: Dell PowerVault 220S and 221S Systems User's Guide
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Hz
Abbreviation for hertz.
I/O
Abbreviation for input/output. The keyboard is an input device, and a printer is an output device. In general, I/O activity can
be differentiated from computational activity. For example, when a program sends a document to the printer, it is engaging in
output activity; when the program sorts a list of terms, it is engaging in computational activity.
IRQ
Abbreviation for interrupt request. A signal that data is about to be sent to or received by a peripheral device travels by an
IRQ line to the microprocessor. Each peripheral connection must be assigned an IRQ number. For example, the first serial port
in your system (COM1) is assigned to IRQ4 by default. Two devices can share the same IRQ assignment, but you cannot
operate both devices simultaneously.
K
Kilo, indicating 1,000.
LED
Abbreviation for light-emitting diode. An electronic device that lights up when a current is passed through it.
local bus
On a system with local-bus expansion capability, certain peripheral devices (such as the video adapter circuitry) can be
designed to run much faster than they would with a traditional expansion bus. Some local-bus designs allow peripherals to
run at the same speed and with the same width data path as the system's microprocessor.
MB
Abbreviation for megabyte(s). The term megabyte means 1,048,576 bytes; however, when referring to hard-disk drive
storage, the term is often rounded to mean 1,000,000 bytes.
MHz
Abbreviation for megahertz.
ms
Abbreviation for millisecond(s).
RAID
Abbreviation for redundant array of independent disks.