User's Guide

game packages. Programs require an operating system to run.

PS/2 — personal system/2 — A type of connector for attaching a PS/2-compatible keyboard, mouse, or

keypad.

PXE — pre-boot execution environment — A WfM (Wired for Management) standard that allows networked

computers that do not have an operating system to be configured and started remotely.

RAID — redundant array of independent disks — A system of two or more drives working together for

performance and fault tolerance. RAID drives are typically used on servers and high-end PCs.

The three most common RAID levels are 0, 3, and 5:

Level 0: Provides data striping but no redundancy. Level 0 improves performance but does not

provide fault tolerance.

Level 3: Same as Level 0, but also reserves one dedicated drive for error correction data,

providing good performance and some level of fault tolerance.

Level 5: Provides data striping at the byte level and also stripe error correction information,

resulting in excellent performance and good fault tolerance.

RAM — random-access memory — The primary temporary storage area for program instructions and data.

Any information stored in RAM is lost when you shut down your computer.

readme file — A text file included with a software package or hardware product. Typically, readme files

provide installation information and describe new product enhancements or corrections that have not yet been

documented.

read-Only — Data and/or files you can view but cannot edit or delete. A file can have read-only status if:

It resides on a physically write-protected floppy disk, CD, or DVD.

It is located on a network in a directory and the system administrator has assigned rights only to

specific individuals.

refresh rate — The frequency, measured in Hz, at which your screen's horizontal lines are recharged

(sometimes also referred to as its vertical frequency). The higher the refresh rate, the less video flicker can be

seen by the human eye.

resolution — The sharpness and clarity of an image produced by a printer or displayed on a monitor. The

higher the resolution, the sharper the image.

RFI — radio frequency interference — Interference that is generated at typical radio frequencies, in the range

of 10 kHz to 100,000 MHz. Radio frequencies are at the lower end of the electromagnetic frequency spectrum

and are more likely to have interference than the higher frequency radiations, such as infrared and light.

ROM — read-only memory — Memory that stores data and programs that cannot be deleted or written to by

the computer. ROM, unlike RAM, retains its contents after you shut down your computer. Some programs

essential to the operation of your computer reside in ROM.

RPM — revolutions per minute — The number of rotations that occur per minute. Hard drive speed is often

measured in rpm.

RTC — real time clock — Battery-powered clock on the system board that keeps the date and time after you

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