R

RAM

Random access memory. Semiconductor-based memory that can be read and written by the microprocessor or other hardware devices. Refers to volatile memory, which can be written as well as read.

RAMDAC

RAM digital-to-analog converter. A chip built into some VGA and SVGA display adapters that translates the digital representation of a pixel into the analog information needed by the monitor to display it. The presence of a RAMDAC chip usually enhances overall display performance.

raster

A rectangular pattern of lines.

raster graphics

Also bitmapped graphics. Images defined as a set of pixels or dots in a column-and-row format.

rasterization

The conversion of vector graphics (images described mathematically as points connected by straight lines) to equivalent images composed of pixel patterns that can be stored and manipulated as sets of bits.

real time

In computing, refers to an operating mode under which data is received and processed; the results are returned instantaneously.

real-time processing

Processing that supports real-time functions such as telephony.

Redbook audio

The data format standard for conventional audio CDs used in home stereo systems.

registry

In Windows and Windows NT/Windows 2000, the tree-structured hierarchical database where general system hardware and software settings are stored. The registry supersedes the use of separate INI files for all system components and applications that know how to store values in the registry.

resolution

Number of pixels per unit of area. A display with a finer grid contains more pixels and thus has a higher resolution and is capable of reproducing greater detail in an image.

resource

1. Any sort of set from which a subset can be allocated for use by a client, such as memory, bus bandwidth, or MIPS. This is not the same as resources that are allocated by Plug and Play. 2. A general term that refers to IRQ signals, DMA channels, I/O port addresses, and memory addresses for Plug and Play.

resource arbitrator

In Plug and Play device configuration, a set of functions used by the configuration manager to arbitrate and allocate resources on the PC.

resource conflict

In Plug and Play device configuration, the result of more than one device sharing the same, nonshareable resource. Conflicts can cause the device to be partially functional or nonfunctional, or can cause the PC to malfunction completely.

resource data type function

A function that describes the resource requirements of an ISA expansion card as well as the programmability available on the card and its interdependencies.

RGB

Red-green-blue. The primary colors in color video. Often used to describe a video color-recording scheme and the equipment that uses it. Also, a computer color-display output signal comprised of separately controllable red, green, and blue signals (as opposed to composite video, in which signals are combined prior to output). RGB monitors typically offer higher resolution than composite monitors. Compare with CMYK.

RISC

Reduced instruction set computing. A type of microprocessor design that focuses on rapid and efficient processing of a relatively small set of instructions. RISC architecture limits the number of instructions that are built into the microprocessor, but optimizes each so it can be carried out very rapidly—usually within a single clock cycle.

RISC-based

Refers to computers based on Windows NT/Windows 2000–compatible implementations of RISC processors.

RLE

Run-length encoding. A data-compression technique in which successive bytes of identical data are converted into a 2-byte pair, consisting of the repeated data byte and the repeat count.