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Redundant array of inexpensive disks. Alternate meanings include redundant array of independent disks and redundant array of inexpensive devices.

raise an exception

A deliberate transfer of control to an exception handler when an exception occurs. A kernel-mode component, including any kernel-mode driver, cannot raise an exception while running at IRQL >= DISPATCH_LEVEL without bringing down the system.

See also structured exception handling.

raised IRQL

Generally, any interrupt request level that is greater than PASSIVE_LEVEL, typically written as IRQL > PASSIVE_LEVEL or IRQL >= APC_LEVEL.

Because most kernel-mode drivers rarely run at IRQL = APC_LEVEL, the Windows Driver Kit (WDK) often uses "raised IRQL" to mean IRQL >= DISPATCH_LEVEL. Writers of file system drivers, which sometimes run at IRQL = APC_LEVEL, should refer to Installable File System (IFS) documentation for information about the IRQL at which file system driver routines are called.

For more information, see the topic Managing Hardware Priorities.

See also DIRQL, IDT, and IRQL.


See RAM digital-to-analog converter (RAMDAC).

RAM digital-to-analog converter (RAMDAC)

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.


A finite and discrete sequence of values. Note that a virtual address range can be backed by a set of discontiguous physical pages or by a file stored in discontiguous sectors on disk.

raster operation (ROP)

A bitwise operation applied to the bits of color data for the replicated brush and the bits of color data for the target rectangle on the display. There are 256 ROPs in Windows.


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.


A system-supplied file system driver (FSD) that is the last resort for all input/output (I/O) requests that require file-system support. When the I/O manager calls active file systems to mount a volume, RAW is always called last because it supports all disk and tape media. However, RAW supplies primitive file-handling capabilities. That is, it does not impose any on-disk file structure or metadata structures for the information on the media; it simply allows read/write access to the logical blocks on the physical disk.

RAW is not an acronym.

raw device

A device running in raw mode.

raw mode

The mode of operation in which a device's driver stack does not include a function driver. A device running in raw mode is being controlled primarily by the bus driver. Upper-level, lower-level, and/or bus filter drivers might be included in the driver stack.

If a bus driver can control a device in raw mode, it sets RawDeviceOK in the DEVICE_CAPABILITIES structure.

realized brush

A data structure containing information and accelerators that the display driver needs in order to fill an area with a pattern.

receive signal strength indication (RSSI)

Indicates a measure of the strength of the radio signal that is being received. The greater the signal, the better the reception.

Redbook audio

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

red green blue (RGB)

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 that consists of separately controllable red, green, and blue signals (as opposed to composite video, in which signals are combined prior to output).

Compare with CMYK.


A system-supplied (network) file system driver that provides access to files on remote machines.

reduced instruction set computer (RISC)

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.

reference block

In DirectX Video Acceleration, the block area extracted from reference frame buffer.


A range of virtual addresses. When a user-mode caller creates a section or maps a view, it must specify a region. The memory manager rounds the specified region's starting address down to the nearest 64K boundary and rounds its size in bytes up to the next host-page-size boundary.


A configuration registry. A database that contains configuration and control information for the system, including information about file systems and drivers. The configuration manager exports system services to manipulate registry key objects contained in the database. For more information, see Registry Keys for Drivers and the Registry functions.

See also key object.

remote procedure call (RPC)

A call from a thread of one process (the client) to a thread of another process (that server) that exists in a different address space, usually on another networked machine.

See also interprocess communication (IPC).

request to send (RTS)

A control packet used by a station to indicate that it has data to send. After sending an RTS, the station must receive a clear to send (CTS) from the destination station before transmitting data packets.

See also clear to send.

residual difference decoding

In DirectX video acceleration, decoding of the waveform that represents the error signal that has been encoded to represent whatever signal remains after motion-compensated prediction as appropriate. This may entail simply an intra representation of a nonpredicted waveform or an inter difference after prediction.


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.

  1. An entity (such as a device object, file object, section object, variable, structure, or buffer) visible to one or more processes.
  2. In kernel mode, a system-defined type of opaque variable manipulated by the support routines. A shared resource is a multiprocessor-safe synchronization mechanism, rather like a gating semaphore with a dynamic limit value. Drivers, usually file systems, can use one or more resource variables to control access to a memory entity, such as a file or database, on a multiple-reader (shared access), single-writer (exclusive access) basis.

In particular, file systems that support caching files and paging I/O share certain resource variables with the cache manager and memory managers.

resource descriptor

An entry in a Resource Requirements List, specifying a range of Hardware Resources that a device instance is capable of using, or an entry in a Resource List, specifying a hardware resource that has been assigned to a device instance.

resource interchange file format (RIFF)

A tagged-file specification used to define standard formats for multimedia files. The tagged-file structure helps prevent compatibility problems that often occur when file-format definitions change over time. Because each piece of data in the file is identified by a standard header, an application that does not recognize a given data element can skip over the unknown information.


See red green blue (RGB).


See resource interchange file format (RIFF).

RIFF chunk

A chunk whose ID is resource interchange file format (RIFF), and that includes an identifying code and zero or more sub-chunks, the contents of which depend on the form type.

RIFF file

A file whose format complies with one of the published resource interchange file format (RIFF) forms. Examples of RIFF files include WAVE files for waveform audio data, RMID files for MIDI sequences, and RDIB files for bitmaps.

RIFF form

A file-format specification based on the resource interchange file format (RIFF) standard.


See reduced instruction set computer (RISC).

RLE bitmaps

See run-length encoded (RLE) bitmap.


See raster operation (ROP).

root partition

Within the hypervisor, a partition that has no parent.

root-enumerated device

A device whose physical device object (PDO) is owned by the Plug and Play (PnP) manager. Root-enumerated devices are typically either non-PnP devices or software-only devices. The driver for a non-PnP device registers its device as a root-enumerated device by calling IoReportDetectedDevice the first time it is loaded. An application can enumerate a software-only device by calling the SetupDiCreateDeviceInfo routine.


See remote procedure call (RPC).


See receive signal strength indication (RSSI).

Rtl routines

See run-time library (Rtl) routines.


See request to send (RTS).

RTS threshold

The RTS threshold is the packet size at which packet transmission is governed by the RTS/CTS transaction. The IEEE 802.11-1997 standard allows for short packets to be transmitted without RTS/CTS transactions. Each station can have a different RTS threshold. RTS/CTS is used when the data packet size exceeds the defined RTS threshold.


As a noun:

  1. Within an MCB, a contiguous range of VBNs mapped to a contiguous range of LBNs (also called an "extent").
  2. Slang for a quantum, as in "when the thread is given the run...."

As a verb:

  • To execute on a processor.
run-length encoded (RLE) bitmap

A bitmap that is compressed to reduce disk and memory storage required for the bitmap. The encoding format is specified in the biCompression member of the BITMAPINFO structure.

run-time library (Rtl) routines

There are two general sets of (C) run-time library routines supplied with the system, one each for user mode and for kernel mode. All kernel-mode drivers can call the kernel-mode RtlXxx routines.

run-time priority inversion

A condition that can occur when threads with mismatched priority attributes share resources or when a higher priority thread waits for a lower priority thread to complete some action. Such an inversion occurs whenever:

  • A high priority thread is blocked, waiting for a lower priority thread to release a shared resource or to complete an action (and probably to set a dispatcher object to the Signaled state).
  • This lower priority thread is also blocked, because many other higher priority threads are ready for execution, so they will be run first.

Under these circumstances, the waiting high-priority thread undergoes a run-time priority inversion, because one or more lower priority threads will run before it does. Note that two threads with mismatched priorities must be very careful to avoid deadlocks if they "share" a resource in a mutually exclusive manner (that is, only one thread at a given time can access the resource).

See also priority, resource, and deadlock.



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