Computer Glossary (Must See)

Computer Glossary, Acronyms, and Abbreviations

1394 class

The class of filters that provide a bus interface and bus enumerator for the IEEE 1394 bus. Firewire

A

ABR

available bit rate

AC-3

An audio standard for delivering 5.1 audio developed by Dolby Laboratories. This system compresses six channels of digital audio into 384 Kbps versus 4 Mbps uncompressed.

ACE

access control entry

ACK

acknowledgment signal

ACL

access control list

ACPI

Advanced Configuration and Power Interface. A specification that defines a new interface to the system board that enables the operating system to implement operating-system directed power management and system configuration. Following the ACPI allows system manufacturers to build systems consistent with the OnNow design initiative for instantly available PCs.

ACPI hardware

Computer hardware with the features necessary to support operating system power management and with the interfaces to those features described using the Description Tables as specified in Advanced Configuration and Power Interface Specification.

ACPI Name Space

A hierarchical tree structure in operating-system-controlled memory that contains named objects. These objects can be data objects, control method objects, bus and device package objects, and so on. All the information in the ACPI Name Space comes from the Differentiated System Description Table.

adapter

See device.

adaptive compression

Data compression software that continually analyzes and compensates its algorithm, depending on the type and content of the data and the storage medium.

add-on devices

Devices that are traditionally added to the base PC system to increase functionality, such as audio, networking, graphics, SCSI controller, and so on. Add-on devices fall into two categories: devices built onto the system board and devices on expansion cards added to the system through a system board connector such as PCI.

ADPCM

Adaptive Differential Pulse Code Modulation. An encoding format for storing audio information in a digital format.

ADSL

Asymmetric Digital Subscriber Line. A method for moving data over regular phone lines. An ADSL circuit is much faster than a regular phone connection, and the wires coming into the subscriber's premises are the same (copper) wires used for regular phone service.

ADT

attribute definition table

AEC

acoustic echo cancellation

AEC

Acoustic echo cancellation.

agent

Software that runs on a client computer for use by administrative software running on a server. Agents are typically used to support administrative actions, such as detecting system information or running services.

AGP

Accelerated Graphics Port

AID

analog-to-digital

algorithm

In compression software, refers to a specific formula used to compress or decompress video or other data.

AML

ACPI Machine Language. Pseudocode for a virtual machine supported by an ACPI-compatible operating system and in which ACPI control methods are written. The AML encoding definition is provided in section 16 of the Advanced Configuration and Power Interface Specification.

analog video

A video signal that represents an infinite number of smooth gradations between given video levels. Compare with digital video.

analog

A method of signal representation by an infinitely smooth universe of numeric values. Measurements that are characterized as analog include readings of voltage and current. Analog devices are characterized by dials and sliding mechanisms. Compare with digital.

Anamorphic

Unequally scaled in vertical and horizontal dimensions.

ANSI

American National Standards Institute. A standards-setting, non-governmental organization that develops and publishes standards for voluntary use in the United States.

anti-aliasing

A form of interpolation used in graphics display technology when combining images; pixels along the transitions between images are averaged to provide a smooth transition.

AOAC

always on/always connected

AP

access point

APC

asynchronous procedure call

API

Application programming interface. A set of routines that an applications program uses to request and carry out lower-level services performed by a computer operating system.

APM

Advanced Power Management. 1. A software interface (defined by Microsoft and Intel) between hardware-specific power management software (such as that located in a system BIOS) and an operating system power management driver. 2. An abridgment of the APM BIOS Interface Specification title.

arbitrator

1. A software module in Windows that handles the allocation of hardware resources among devices. 2. Under Windows 95, the Plug and Play device driver responsible for allocating a specific resource among all drivers that require the resource. For example, VDMAD is a DMA-channel arbitrator, and VPICD has services for allocating IRQ lines. Windows 95 provides arbitrators for standard I/O, memory, hardware interrupt, and DMA-channel resources.

ARC

Advanced RISC Computing

architecture

A general term referring to the structure of all or part of a computer system. Also covers the design of system software, such as the operating system, as well as referring to the combination of hardware and basic software that links machines on a computer network.

ARP

address resolution protocol

artifact

An unintended, unwanted visual aberration in a video image.

ASCII

American Standard Code for Information Interchange. The most popular coding method used by small computers for converting letters, numbers, punctuation, and control codes into digital form.

ASIC

Application-specific integrated circuit.

ASL

ACPI Source Language. The programming language equivalent for AML. ASL is compiled into AML images. The ASL statements are defined in section 15 of the Advanced Configuration and Power Interface Specification.

aspect ratio

The relationship of width and height. When an image is displayed on different screens, the aspect ratio must be kept the same to avoid either vertical or horizontal stretching.

ASPI

Advanced SCSI Programming Interface

assigned configuration

Drivers examine this portion of the device node to determine which resources have been allocated for the device. For Plug and Play cards, the assigned resources for a device can change dynamically or from one system start-up to the next.

ASVD

analog simultaneous voice/data

asymmetrical compression

A system that requires more processing capability to compress than to decompress an image. It is typically used for the mass distribution of programs on media such as CD-ROM, where significant expense can be incurred for the production and compression of the program, but the playback system must be low cost. Compare with symmetrical compression.

asynchronous

An operation that proceeds independent of any timing mechanism, such as a clock. Compare with synchronous.

AT IIBM

registered trademark for PC/AT

ATA

AT Attachment. An integrated bus usually used between host processors and disk drives. Used interchangeably with IDE.

ATAAT

Attachment

ATAPI

AT Attachment Packet Interface. A hardware and software specification that documents the interface between a host computer and CDROM drives using the ATA bus.

ATM

Asynchronous transfer mode. A transmission protocol that segments user traffic into small, fixed size units called cells, which are transmitted to their destination, where they are reassembled into the original traffic. During transmission, cells from different users may be intermixed asynchronously to maximize utilization of network resources.

audio class

The class of filters that deals with pulse code modulation or similar digitized data or analog signals. A WDM audio minidriver provides support for audio devices under the WDM digital audio architecture.

audio mixing

The method of combining multiple streams of audio data into a single stream through some method such as addition and clipping.

AVD

alternating voice/data

AVI

audio-visual interface

B

bandwidth

Usually used in reference to the amount of data per unit of time that must move from one point to another, such as from CD-ROM to processor.

BAR

base address register

BDC

backup domain controller

BDK

Business Development Kit

BIOS

Basic input/output system. A set of routines that works closely with the hardware to support the transfer of information between elements of the system, such as memory, disks, and the monitor. Although critical to performance, the BIOS is usually invisible to the end user; however, programmers can access it.

BIOS enumerator

Responsible in a non-ACPI Plug and Play system for identifying all hardware devices on the motherboard of the computer. The BIOS supports an API that allows all Plug and Play computers to be queried in a common manner.

bit map

Representation of characters or graphics by individual pixels arranged in rows (horizontal) and columns (vertical). Each pixel can be represented by either 1 bit (simple black and white) or up to 3 2 bits (high-definition color).

bit specifications

Number of colors or levels of gray that can be displayed at one time. Controlled by the amount of memory in the computer's graphics controller card. An 8-bit controller can display 256 colors or levels of gray; a 16-bit controller, 64,000 colors; and a 24-bit controller, 16.8 million colors.

bit-mapped graphics

Images created with matrices of pixels or dots. Also raster graphics.

blt

block transfer

BOOTP

bootstrap protocol

BPC

Broadcast PC

bpp

Bits per pixel. The number of bits used to represent the color value of each pixel in a digitized image.

bps

Bits per second. The number of bits transferred per second in a data communications system. A measure of speed.

BRI

basic rate interface

brightness

The value associated with a pixel, representing its gray value from black to white.

broadcast architecture

The set of technologies that enable PCs to receive broadcast data.

BSD

Berkeley Software Distribution (UNDC)

buffer

A reserved portion of memory in which data is temporarily held pending an opportunity to complete its transfer to or from a storage device or another location in memory.

bus enumerator

In a Plug and Play system, a bus device driver that detects devices located on a specific bus and loads information about devices into the hardware tree.

C

CA

Computer Associates International, Inc.

cache

A special memory subsystem in which frequently used data values are duplicated for quick access. Cache memory is always faster than RAM.

CAD

computer aided design

CAM

common Access Method

Card Services

Under Windows 95, a protected mode system component that is a VxD linked with the PCMCIA bus driver. Card Services passes the event notification from socket services to the PCMCIA bus driver, provides information from the computer's cards to the PCMCIA bus driver, and sets up the configuration for cards in the adapter sockets.

CBQ

class-based queuing

CBT

computer based training

CCITT

Comite Consultatif Internationale de Telegraphie et Telephonie (Consultative Committee for International Telephone and Telegraph). An international standards organization dedicated to creating communications protocols that will enable global compatibility for the transmission of voice, data, and video across all computing and telecommunications equipment.

CCP

compression control protocol

CD

compact disc

CD-I

Compact Disc Interactive. A compact disc format (developed by NV Philips and Sony Corporation) that provides audio, digital data, still graphics, and limited-motion video.

CDB

command descriptor blocks

CDFS

Compact disc file system. Controls access to the contents of CD-ROM drives.

CD-I

Compact Disc Interactive

CDMA

code-division multiple access

CD-R2

Physical format for CD read-only

CD-ROM

Compact disc read-only memory. A 4.75 -inch laser-encoded optical memory storage medium (developed by NV Philips and Sony Corporation) with the same constant linear velocity (CLV) spiral format as compact audio discs and some videodiscs. CD-ROMs can hold about 550 MB of data.

CE

consumer electronics

CHAP

challenge handshake authentication protocol

chroma, chrominance

1. The color portion of the video signal that includes hue and saturation information. Requires luminance, or light intensity, to make it visible. 2. Hue is defined as tint. Saturation indicates the degree to which the color is diluted by luminance (or by white light). Compare with luminance.

CHS

cylinder head sector

CI

Component Instrumentation

CIE

Commission International de I'Eclairage. The international commission on illumination. Developer of color matching systems.

CIM

Common Information Model

CINF

check (modem) INF tool

CIS

Card information structure.

CISC

complex instructions set computers

Cl

Component Instrumentation. A specification for DMI related to the service layer.

class

For hardware, the manner in which devices and buses are grouped for purposes of installing and managing device drivers and allocating resources. The hardware tree is organized by device class, and Windows 95 uses class installers to install drivers for all hardware classes.

class driver

A driver that provides system required hardware-independent support for a given class of physical devices. Such a driver communicates with a corresponding hardware dependent port driver, using a set of system-defined device control requests, possibly with additional driver-defined device control requests. Under WDM, the class driver creates a device object to represent each adapter registered by minidrivers. The class driver is responsible for multiprocessor and interrupt synchronization.

CMOS

complementary metal-oxide semiconductor

CMP

connection management protocol

CMYK

Cyan-magenta-yellow-black. A mixing model or method of describing colors used with many printing systems. Uses subtractive primaries, starting with white and subtracting percentages of cyan (blue), magenta (red), and yellow to yield desired colors.

codec

Coder-decoder. A filter for data that manipulates it in some form, usually by compressing or decompressing the data stream.

color keying

To superimpose one image over another for special effects.

COM

1) Component Object Model; the core of OLE. Defines how OLE objects and their clients interact within processes or across process boundaries. 2) Legacy serial port.

compatibility mode

An asynchronous, host-to peripheral parallel port channel defined in the IEEE 1284-1944 standard. Compatible with existing peripherals that attach to the Centronics-style PC parallel port.

composite video

A signal that combines the luminance, chrominance, and synchronized video information onto a single line. This has been the most prevalent NTSC video format.

compressed video

A digital video image or segment that has been processed using a variety of computer algorithms and other techniques to reduce the amount of data required to accurately represent the content and thus the space required to store the content.

compression

The translation of data (video, audio, digital, or a combination) to a more compact form for storage or transmission.

concatenate

To join sequentially.

Configuration Manager

The Windows 95 Plug and Play system component that drives the process of locating devices, setting up their nodes in the hardware tree, and running the resource allocation process. Each of the three phases of configuration management-boot time (BIOS), real mode, and protected mode-have their own configuration managers.

connection

A negotiated method of communication between devices, whether implemented in hardware or software.

contrast

The range of light and dark values in a picture; or a measure of brightness content in an image. The range between the lightest tones and the darkest tones in an image.

control method

A definition of how an ACPI compatible operating system can perform a simple hardware task. For example, the operating system invokes control methods to read the temperature of a thermal zone. Control methods are written in an encoded language called AML. An ACPI compatible system must provide a minimal set of control methods in the ACPI tables. The operating system provides a set of well-defined control methods that ACPI table developers can reference in their control methods.

controllerless modem

Also host-based controller. A modem that consists of a DSP without the usual microcontroller. The host CPU provides the AT command interpreter, modem-control functions, and v.42bis implementation. Compare with software modem.

convergence

In an RGB monitor, where red, green, and blue signals all converge in one pixel. At full convergence, the RGB pixel would be white.

CPU

Central processing unit. The computational and control unit of a computer; the device that interprets and executes instructions. By definition, the CPU is the chip that functions as the "brain" of the computer.

CRC

cyclic redundancy check

CSA

Connection and Streaming Architecture. Kernel-mode streaming in WDM.

CSEL

Cable Select

CSN

Card Select Number

CSN

Card Select Number. The handle created by the system BIOS or the operating system through the isolation process and assigned as a unique identifier to each Plug and Play card on the ISA bus.

CSR

command and status register

CTS

Clear To Send

D

DAA

data access arrangement

DAC

digital-to-analog converter

DARPA

Defense Advanced Research Project Agency

DASD

direct access storage device

DAT

Digital audio tape. A consumer recording and playback media for high-quality audio.

data rate

The speed of a data transfer process, normally expressed in bits per second or bytes per second.

dbr

decibels above reference noise

DBS

Digital Broadcast Service/System/satellite

DC

device context

DCD

Data Carrier Detect

DCE

Data Communications Equipment

DCI

Display Control Interface

DCOM

Distributed Component Object Model

DDC

Display data channel. The Plug and Play baseline for monitors. The communications channel between a monitor and the display adapter to which it is connected. This channel provides a method for the monitor to convey its identity to the display adapter.

DDE

dynamic data exchange

DDI

Device driver interface.

DDK

Device driver kit.

DDL

data definition language

DDML

Display Driver Management Layer

DDN

Defense Data Network

decompression

To reverse the procedure conducted by compression software, and thereby return compressed data to its original size and condition.

density

The degree of darkness of an image. Also, the percent of screen used in an image.

device

1. Any circuit that performs a specific function, such as a parallel port. 2. For WDM, usually refers to a device object but also refers to a unit of hardware-for example, an audio adapter that is detected by Plug and Play.

Device Bay

An industry specification that defines a mechanism for both peripheral devices and system bays that allows adding and upgrading PC peripheral devices without opening the chassis.

device ID

A unique ASCH string created by enumerators to identify a hardware device and used to cross-reference data about the device stored in the registry. Distinguishes each logical device and bus from all others on the system.

device node

The basic data structure for a given device, built by the Configuration Manager. Device nodes are built into memory at system startup for each device and enumerator. Each device node contains information about the device, such as currently assigned resources. The complete hierarchical representation of all device nodes, representing all currently installed devices, is referred to as the hardware tree.

device object

A kernel-mode-only object type used to represent a physical, logical, or virtual device whose driver has been loaded into the system.

devnode

See device node.

DHCP

Dynamic Host Configuration Protocol

DIB

Device-independent bitmap. A file format designed to ensure that bitmap graphics created using one application can be loaded and displayed in another application exactly the way they appeared m the originating application.

digital

A method of signal representation by a set of discrete numerical values, as opposed to a continuously fluctuating current or voltage. Compare with analog.

digital video

A video signal represented by computer-readable binary numbers that describe a finite set of colors and luminance levels. Compare with analog video.

digitization

The process of transforming analog video signal into digital information.

DIP

dual in-line package

Dir-sync

See DSS.

disk I/O controller

Also HDC. A special-purpose chip and circuitry that directs and controls reading from and writing to a computer's disk drive.

DLC

Data Link Control

DLL

Dynamic link library. API routine that User mode applications access through ordinary procedure calls. The code for the API routine is not included in the user's executable image. Instead, the operating system automatically modifies the executable image to point to DLL procedures at run time.

DLS

Distributed Link Services

DMA

Direct memory access. A method of moving data from a device to memory (or vice versa) without the help of the microprocessor. The system board uses a DMA controller to handle a fixed number of channels, each of which can be used by only one device at a time.

DMI

Desktop Management Interface. A framework created by the DMTF. DMTF specifications define industry-standard interfaces for instrumentation providers and management applications.

DMTF

Desktop Management Task Force.

DNS

Domain Name System

dock

To insert a portable computer into a base unit. Cold docking means the computer must begin from a power-off state and restart before docking. Hot docking means the computer can be docked while running at full power. See also warm docking.

docking station

The base computer unit into which a user can insert a portable computer, expanding it to a desktop equivalent. A typical docking station provides drive bays, expansion slots, all the ports on an equivalent desktop computer, and AC power.

dongle

A physical device, attached to a PC's I/O port, that adds hardware capabilities.

DOS

disk operating system

DPC

Deferred procedure call. Method used in Windows NT for event scheduling.

DPI

dots per inch

DPMI

DOS Protected Mode Interface

DPMS

Display Power Management Signaling

DRAM

Dynamic Random Access Memory

driver

Kernel-mode code used either to control or emulate a hardware device.

driver stack

Device objects that forward IRPs to other device objects. Stacking always occurs from the bottom up and is torn down from the top.

DS

Directory Services

DSE

development software engineer

DSL

Digital Subscriber Line

DSLAM

DSL Access Multiplexer

DSP

Digital signal processor. An integrated circuit designed for high-speed data manipulations. Used in audio communications, image manipulation, and other data-acquisition and data-control applications.

DSS

Microsoft Mail directory synchronization (dir-sync) server

DSVD

digital simultaneous voice/data

DTMF

dual tone multifrequency

DTR

Data Terminal Ready

DVD

Optical disk storage that encompasses audio, video, and computer data.

dynamic detection

The process by which a system can detect that a new device has been added or removed from the PC. This process allows the operating system and applications to immediately begin using the added devices or stop using the removed devices without rebooting the system.

E

EA

extended attributes

ECC

error correction code

ECP

extended capabilities port

ECP

Extended capabilities port. An asynchronous, 8-bit-wide parallel channel defined by IEEE 12841944 that provides PC-to-peripheral and peripheral to-PC data transfers.

ECR

engineering change request (for PCI)

EDID

Expended Display Identification Data

EDO DRAM

Short for Extended Data Output Dynamic Random Access Memory, a type of DRAM that is faster than conventional DRAM. Unlike conventional DRAM, which only allows one byte to be read at a time, EDO DRAM can copy an entire block of memory to its internal cache. While the processor is accessing this cache, the memory can collect a new block to send. Note that EDO DRAM is faster than conventional DRAM only if the cache controller supports a transfer mode known as pipeline burst. Nearly all PCs that support EDO DRAM are equipped with such a controller.

EE

Eastern European

EET

enhanced environment technology

EIA

Electronics Industries Association

EIDE

Enhanced Integrated Device Electronics

EISA

Extended Industry Standard Architecture. A 32-bit PC expansion bus designed as a superset of the ISA bus. Designed to expand the speed and data width of the legacy expansion bus while still supporting older ISA cards.

EMB

extended memory block

embedded controller

The general class of microcontrollers used to support OEM-specific implementations, mainly in mobile environments. The embedded controller performs complex low-level functions through a simple interface to the host microprocessor(s).

embedded controller interface

ACPI defines a standard hardware and software communications interface between an operating system driver and an embedded controller-for example, Smart Battery and AML code. This allows any operating system to provide a standard driver that can directly communicate with an embedded controller in the system, thus allowing other drivers to communicate with and use the resources of system embedded controllers.

EMF

enhanced metafile

enumeration

The process by which logical devices and buses, and their available resources, are identified by Plug and Play during system setup.

enumerator

A Plug and Play device driver that detects devices below its own device node, creates unique device IDs, and reports to Configuration Manager during startup. For example, a SCSI adapter provides a SCSI enumerator that detect devices on the SCSI bus.

EPP

extended parallel port

ESCD

Link to information

ESDI

Enhanced Small Device Interface

event set

A uniquely identified set that represents a group of items about which a client can be notified.

expansion bus

A group of address, data, and control lines that provide a buffered interface to devices located either on the system board or on cards that are plugged into expansion connectors. Common expansion buses included on the system board are USB, PC Card, and PCI.

expansion card

A card that connects to an expansion bus and contains one or more devices.

expansion ROM

See option ROM.

F

FAT

File allocation table. A table or list maintained by an operating system to keep track of the status of various segments of disk space used for file storage.

FC-AL

Fibre Channel Arbitrated Loop

FCB

file control block

FCP

function control protocol

FDC

Floppy disk drive controller. A special purpose chip and associated circuitry that directs and controls reading from and writing to a computer's disk drive.

FDDI

Fiber Distributed Data Interface

field

One half of a television picture. One complete vertical scan of the picture, containing 262.5 lines. Two fields make a complete television picture (frame). The lines of field 1 are vertically interlaced with the lines of field 2 for 525 lines of resolution.

FIFO

First in/first out. A method for processing a queue m which items are removed in the same order they were added.

filters

Atomic components that provide the basic building blocks for processing data. Under the WDM Stream architecture, also known as a functional device or multimedia processing driver. Each filter's capability is described in put by a number of connection points called pins. Each pin can consume, produce, or both consume and produce a data stream such as digital audio. Specialized tasks can be solved by connecting filters by way of their pins into a topology-for example, to play filtered and mixed audio. Under WDM, a filter is implemented as a kernel-mode entity that is a device object usually implemented by a kernel driver. Under ActiveMovie, a filter is a User-mode entity that is an instance of a COM object, usually implemented by a DLL.

FM

frequency modulation

FPM

Fast page mode (DRAM).

fps

Frames per second.

FQDN

fully qualified domain name

FR

frame relay

frame

A single screw-sized image that can be displayed in sequence with other slightly different images to create animated drawings. A video frame consists of two interlaced fields of either 525 lines (NTSC) or 625 lines (PAL/SECAM), running at 30 frames per second (NTSC) or 25 frames per second (PAL/SECAM). Film runs at 24 frames per second

FRS

File Replication Service

FSD

file system driver

FTP

file transfer protocol

FTS

fault tolerance system

full duplex

In terms of data flow, indicates bi-directional data flow.

full-motion video

Video reproduction at 30 frames per second (NTSC-original signals) or 25 frames per second (PAL-original signals). See also frame.

functional device

See filters.

G

GAL

Global Address List

GB

Gigabyte.

GDI

Graphics Device Interface

GDT

Global Descriptor Table

GIF

Graphics Interchange Format

GP

general protection

gray scale

The spectrum (range) of shades of black that an image has.

GSM

global system for mobile communications

GUI

graphical user interface

GUID

Globally unique identifier. A 16-byte value generated from the unique identifier on a adapter, the current date and time, and a sequence number. This is used to allow any party to create identifiers that will be guaranteed not to overlap with other similarly created identifiers.

H

HAL

hardware abstraction layer

hardware branch

The hardware archive root key in the registry that is a superset of the memory resident hardware tree. Although the hardware tree contains information only about those devices currently detected and running the system, the registry contains a complete list of all hardware ever installed on the particular computer. The hardware root key is \\\Hkey_Local_Machine\Hardware.

hardware tree

A record in RAM of the current system configuration based on the configuration information for all devices in the hardware branch of the registry. The hardware tree is created each time the system is started or whenever a dynamic change occurs to the system configuration.

HCI

Host controller interface. System-level interface supporting USB.

HCL

Hardware Compatibility List. See WHQL.

HCT

Hardware Compatibility Tests. A suite of tests from WHQL to verify hardware and device driver operations under a specific operating environment. These tests exercise the combination of a device, a software driver, and an operating system under controlled conditions to verify that all components operate properly.

HDC

Hard disk I/O controller.

HDLC

high-level data link control

HDTV

High-definition TV. A proposed standard that recommends doubling the current 525 lines per picture to 1050 lines, and increasing the screen aspect ratio (that is, width to height) from the current 12:9 to 16:9, which would create a television screen shaped more like a movie screen.

HFC

hybrid fiber-coax

HID

Human Interface Device

high resolution

An adjective describing improvement in display image quality as a result of increasing the number of pixels per square inch.

HMA

high-memory area

HMOM

Hypermedia Object Manager

HPFS

high-performance file system

HSB

Hue-saturation-brightness. With the HSB model, all colors can be defined by expressing their levels of hue (the pigment), saturation (the amount of pigment), and brightness (the amount of. white included), in percentages.

HSCDS

high-speed cable data services

HSM

hierarchical storage management

HTML

hypertext markup language

HTTP

hypertext transport protocol

hue

The color tint of an image. The color of the analog video signal is determined by three factors: hue, saturation, and luminance.

Human Interface Device Specification

The device class definition developed by the USB standards group for HIDS. Serves as the basis for the WDM input device support, and unifies input devices by providing flexible data reporting, typeless data, and arrayed and variable input and output.

Hz

Hertz (cycles per second).

I

I/O

Input/output. Two of the three activities that characterize a computer (input, processing, and output). Refers to the complementary tasks of gathering data for the microprocessor to work with and make the results available to the user through a device such as the display, disk drive, or printer.

I20

Intelligent I/O.

IA-PC

Intel Architecture Personal Computer. A general descriptive term for computers built with processors conforming to the architecture defined by the Intel processor family based on the 486 instruction set and having an industry-standard PC architecture.

ICC

International Color Consortium

ICD

installable Client Driver. An OpenGL driver model in which the driver is responsible for implementing the entire OpenGL pipeline. Intended for high-end graphics cards that implement most of the OpenGL pipeline in hardware.

ICM

image color matching

ICMP

Internet control message protocol

ID

identification

IDE

Integrated Device Electronics. A type of diskdrive interface where the controller electronics reside on the drive itself, eliminating the need for a separate adapter card.

IDT

Internet Development Toolbox

IEEE

Institute of Electrical and Electronics Engineers. Organization that developed the IEEE 802 standards, among others, for the physical and data-link layers of LANs following the ISO/OSI model.

IETF

Internet Engineering Task Force.

IFS

installable file system

IFSMGR

Installable File System Manager

IGN

Internet group names

IHV

Independent hardware vendor.

IIS

Internet Information Server

IMADPCM

music-oriented code

image

The computerized representation of a picture or graphic.

image resolution

The fineness or coarseness of an image as it is digitized; measured in dots per inch (DPI), typically ranging from 200 to 400 DPI.

in

In terms of data flow, indicates consumption of data. An in pin is compatible with an out pin.

INF file

Information file. A file created for a particular adapter that provides the operating system with information required to set up a device, such as a list of valid logical configurations for the device, the names of driver files associated with the device, and so on. An INF file is typically provided by the device manufacturer on a disk with an adapter.

INI file

Initialization file. Commonly used under Windows 3.x and earlier, INI files have been used by both the operating system and individual applications to store persistent settings related to an application, driver, or piece of hardware. In Windows NT and Windows 95, INI files are supported for backward compatibility, but the registry is the preferred location for storing such settings.

input class

The class of filters that provide an interface for HID hardware, including USB and legacy devices, plus proprietary and other HID hardware, under the WDM HID architecture.

instantiate

In object-oriented programming, to create an instance of a class.

instrumentation

A mechanism for reporting information about the state of PC hardware and software to enable management applications to ascertain and change the state of a PC and to be notified of state changes.

integrated device

Any device such as a parallel port, graphics adapter, and so on-that is designed on the system board rather than on an expansion card.

interactive video

A video program and a computer program running in tandem under the control of the user. In interactive video, the user's actions, choices, and decisions genuinely affect the way in which the program unfolds.

interface

For parameters on a connection request a specific set of methods and properties implemented on a medium that a filter connection uses to communicate, such as a specific set of IOCTLs.

interframe coding

Compression techniques that track the differences between frames of video. This results in more compression over a range of frames than intraframe coding.

interlaced

1. A scanning method that divides the screen into two fields, alternately drawing odd numbered and even-numbered scan lines. 2. A scheme to display a video image by displaying alternate scan lines in two discrete fields. Interlaced signals are used in broadcast video and are required for video to be compliant with NTSC.

interpolation

The process of averaging pixel information when scaling an image. When reducing the size of an image, pixels are averaged to create a single new pixel; when an image is scaled up in size, additional pixels are created by averaging pixels of the smaller image.

intraframe coding

Compression within each frame individually. This results in less compression over a range of frames than interframe coding.

IOCTL

Input/output control. A custom class of IRPs available to User mode. Each WDM class driver has a set of IOCTLs that it uses to communicate with applications. The IOCTLs give the class driver information about intended usage by applications. The class driver performs all IOCTL parameter validation.

IOS

I/O supervisor

IP

Internet Protocol

IPC

interprocess communication

IPL

Initial program load. A device used by the system during the boot process to load an operating system into memory.

IPX

Internetwork Packet Exchange

Ir

infrared

IRC

Internet relay chat

IrDA

Infared Data Association

IrLAP

Ir Link Access Protocol

IrLMP

Ir Link Management Protocol

IRP

I/O request packet. Data structures that drivers use to communicate with each other. The basic method of communication between kernel-mode devices. An IRP is a key data structure for WDM, which features multiple layered drivers. In WDM, every I/O request is represented by an IRP that is passed from one driver layer to another until the request is complete. When a driver receives an IU, it performs the operation the IRP specifies, and then either passes the IRP back to the I/O Manager for disposal or onto an adjacent driver layer. An IRP packet consists of two parts: a header and the I/O stack locations.

IRP_MJ_XXX

IRP Major. One of a predefined class of IRPs that a device can accept.

IRQ

Interrupt request. A method by which a device can request to be serviced by the device's software driver. The system board uses a PIC to monitor the priority of the requests from all devices. When a request occurs, the microprocessor suspends the current operation and gives control to the device driver associated with the interrupt number issued. The lower the number-for example, IRQ3-the higher the priority of the interrupt. Many devices only support raising requests of specific numbers.

ISA

Industry Standard Architecture. An 8-bit (and later, a 16-bit) expansion bus that provides a buffered interface from devices on expansion cards to the PC internal bus.

ISAPI

Internet Server API

ISDN

Integrated Service Digital Network. A set of communications standards that enable a single phone line or optical cable to carry voice, digital network services, and video.

ISIS

Image and Scanner Interface Specification

ISO

International Standards Organization.

ISO/OSI

International Standards Organization Open Systems Interconnection model. A layered architecture that standards levels of service and types of interaction for computers exchanging information through a communications network.

isochronous

Refers to a communication protocol based on time slices rather than handshaking. For example, a process might have 20 percent of total bus bandwidth. During its time slice, the process can stream data.

isolation

The Plug and Play process by which cards on an ISA bus are distinguished from each other after system startup.

ISP

Internet service provider

ISR

Interrupt service routine. A routine whose function is to service a device when it generates an interrupt.

ISV

independent software vendor

ITU

International Telecommunication Union

ITV

interactive television

IVR

interactive voice response

J

JPEG

Joint Photographic Experts Group. A working committee under the guidance of the ISO that is attempting to define a proposed universal standard for the digital compression and decompression of still images for use in computer systems.

K

KB

Kilobyte.

KDT

keyboard definition table

kernel

The core of the layered architecture that manages the most basic operations of the operating system, such as sharing the processor between different blocks of executing code, handling hardware exceptions, and other hardware-dependent functions.

kernel mode

The processor mode that allows full, unprotected access to the system. A driver or thread running in kernel mode has access to system memory and hardware.

kernel-mode driver

Driver for logical, virtual, or physical devices. Part of the underlying operating system that supports ring 0 operations.

kHz

kilohertz

L

L2

Level 2

LAN

Local area network. A group of computers and other devices dispersed over a relatively limited area and connected by a communications link that enables any device to interact with any other device on the network. Compare with WAN.

layered driver

One of a collection of drivers that responds to the same IRPS. Layered driver describes the highest-level and lowest-level drivers in a chain of layered drivers that process the same IRPS, along with all intermediate drivers in the chain.

LBA

logical block addressing

LCD

liquid crystal display

LDAP

lightweight directory access protocol

LED

light-emitting diode

legacy

Any feature in the PC system based on older technology for which compatibility continues to be maintained in other sytem components.

LFN

long file name

LIM

Lotus-Intel-Microsoft

local bus

Usually refers to a system bus directly connected to the microprocessor on a system board. Used colloquially to refer to system board buses located closer to the microprocessor than are ordinary expansion buses (that is, with less buffering), which are therefore capable of greater throughput.

lossless compression

Ensures that the original data is exactly recoverable with no loss in image quality.

lossy compression

The original data is not completely recoverable. Although image quality may suffer, many experts believe that up to 95 percent of the data in a typical image may be discarded without a noticeable loss in apparent resolution.

LPT

line printer

LRU

Least-recently used. Algorithm for paging.

LSB

least significant bit

luminance

Used to describe the black-and-white component of a video signal. The amount of luminance contained in a video signal is directly related to the amount of light intensity. Also, brightness; one of the three image characteristics coded in composite television (represented by the letter Y). See YUV.

M

MAC

Media Access Control

MADK

Microsoft active Development Kit

MAPI

Messaging Application Program Interface

master clock

Controls the rate of reference time within a graph and is used by filters within the graph to synchronize presentation times. Provides a standard mechanism to query the reference time, to query the physical clock time and rate (compared to the system clock) of the owner of the master clock, and to establish event notifications based on position changes in the master clock's reference time.

MB

Megabyte.

MBONE

multicast backbone

Mbps

megabits per second

MCA

Micro Channel Architecture

MCD

Miniclient Driver. An OpenGL driver model in which the driver is responsible only for handling those features that can be accelerated in hardware, leveraging software implementation to handle the rest of the pipeline.

MCI

Media Control Interface

MCL

Microsoft Compatibility Labs

MCT

Modem Compatibility Test

MDI

multiple document interface

MDK

Modem Developers Kit

MDL

Memory descriptor list. In Windows NT, an opaque structure, defined by Memory Manager, that uses an array of physical page frame numbers to describe the pages that back a virual memory range.

method set

Used in Windows NT and WDM drivers to perform an action, such as allocating memory, and to provide a way to access related actions. Each method set has a unique identifier used to retrieve that method set and can be fulfilled either synchronously or asynchronously. A resource method set contains resource-specific methods for manipulating a type of resource by a kernel-mode client, and is used in resource allocation by enumerated devices on a bus.

MFT

master file table

MHz

megahertz

MI

Management Interface

MIB

Management Information Base

Microsoft ActiveMovie

A cross-platform API for developers of multimedia applications that provides a User-mode connection and Stream architecture to support high-quality digital video, high-fidelity audio, and special effects.

Microsoft DirectX

A low-level API that provides User-mode media interfaces for games and other high-performance multimedia applications. DirectX is a thin layer, providing direct access to hardware services, and takes advantage of available hardware accelerators and emulates accelerator services when accelerators are not present.

MIDI

Musical Instrument Digital Interface. An industry-standard connection for computer control of musical instruments and devices. A hardware and data standard for communicating between hardware. Most references involve only the data standard, which is a byte stream used for controlling musical instruments and storing the output of such instruments.

minidriver

A hardware-specific DLL that uses a Microsoft-provided class driver to accomplish most actions through functions call and provides only device-specific controls. Under WDM, the minidriver registers each adapter with the class driver, which creates the device object. The minidriver uses the class driver's device object to make system calls.

miniport driver

A device-specific kernel-mode driver linked to a Windows NT or WDM port driver, usually implemented as a DLL that provides an interface between the port driver and the system.

MIPS

Millions of instructions per second. A common measure of processor speed.

MIS

Management information system.

mixer class

The class of filters that deal with manipulating controls such as volume, treble, and so on.

MLPPP

multilink point-to-point protocol

MMC

Microsoft Management Console

MMIO

memory-mapped I/O

monolithic driver

A driver that has many different classes of functionality contained in the same driver.

motherboard

See system board.

MPEG

Motion Picture Experts Group. Used when referring to one of several standard video compression schemes. A codec for squeezing full screen, VHS-quality digital video into a small data stream so it can be played from a CD-ROM drive.

MPS

Multiprocessor Specification

MPX

multiplexed ms millisecond

MSB

most significant bit

MSDL

Microsoft Download Library

MSDN

Microsoft Developer Network.

MTD

Memory technology driver. A protected mode driver that works with Windows 95 protected mode PC Card software to enable form-factor cards, such as flash memory cards. Such memory cards and their related drivers do not provide full Plug and Play capabilities.

MTF

Microsoft tape format

MTU

maximum transmission unit

multifunction device

A piece of hardware that supports multiple, discrete functions, such as audio, mixer, and music, on a single adapter.

multimedia

Refers to the delivery of information that combines different content formats (motion video, audio, still images, graphics, animation, text and so forth).

multimedia processing driver

See filters.

music class

The class of filters that deal with music data, such as ZIPI or MMI.

N

NBDD

NetBIOS datagram distribution server

NBNS

NetBIOS name server

NC

network computer

NCB

network control block

NCP

NetWare core protocol

NDA

Non-Disclosure Agreement

NDD

Norton Disk Doctor

NDIS

Network Driver Interface Specification. The interface for network drivers used in Windows and Windows NT. NDIS provides transport independence for network vendors because all transport drivers call the NDIS interface to access the network.

NDS

NetWare Directory Services

NetBEUI

NetBIOS Extended User Interface

NetBIOS

network basic input output system

NetBT

NetBIOS over TCP/IP

NetPC

Network PC. A PC designed to meet the industry specification for Network PC systems, which optimizes PC design for flexibility and manageability in order to reduce the total cost of ownership.

NetX

NetWare 3.x client shell

NFS

Network File System

nibble mode

An asynchronous, peripheral-to-host channel defined in the IEEE 1284-1944 standard. Provides a channel for the peripheral to send data to the host, which is commonly used as a means of identifying the peripheral.

NIC

network interface card

NIS

Network Information Service

NLS

National Language Support

NMI

Nonmaskable Interrupt. An interrupt that cannot be overruled by another service request. A hardware interrupt is called nonmaskable if it bypasses and takes priority over interrupt requests generated by software, the keyboard, and other devices.

NNTP

network news transport protocol

non-interlaced

The method of scanning all lines on a display from top to bottom in sequential order at a specific rate per second. Unlike television, which uses an interlaced scanning method, computers typically use non-interlaced monitors.

NOS

network operating system

NP

network provider

NPI

network provider interface

ns

nanosecond

NSP

Native signal processing.

NTFS

Windows NT file system. An advanced file system designed for use specifically with the Windows NT operating system. NTFS supports file system recovery and extremely large storage media, in addition to other advantages.

NTKERN

The Windows "Memphis" version of the kernel component 'm Windows NT.

NTSC

National Television System Committee of the Electronics Industries Association (EIA). The standards-setting body for television and video in the United States. Sponsor of the NTSC standard for encoding color, a coding system compatible with black-and-white signals and the first system used for color broadcasting in the United States. The broadcast standard for the United States and Japan. See also PAL format and SECAM.

NTSC format

A color-television format having 525 scan lines, a field frequency of 60 Hz, a broadcast bandwidth of 4 MHz, line frequency of 15.75 KHz, frame frequency of 1/30 of a second, and a color subcarrier frequency of 3.5 8 MHz. See also PAL format and SECAM.

O

OAK

OEM Adaption Kit

OCR

optical character recognition

ODBC

Open Database Connectivity

ODI

Open Datalink Interface

OEM

Original equipment manufacturer. Used primarily to refer to PC systems manufacturers.

OLE

Object linking and embedding. A way to transfer and share information among applications. OLE is based on the COM programming model and binary standard.

OnNow

A design initiative that seeks to create all the components required for a comprehensive, system-wide approach to system and device power control. OnNow is a term for a PC that is always on but appears off and that responds immediately to user or other requests.

OOP

object oriented programming

OpenHCI

Open Host Controller Interface

OPK

OEM preinstallation kit

option ROM

Optional read-only memory found on PC bus expansion cards. Option ROMs usually contain additional firmware required to properly boot the peripheral connected to the expansion card, for example, a hard drive. Also expansion ROM.

OR

A logical operation for combining two bits or two Boolean values; if one or both values are true, it returns the values of true. Compare with XOR

OS

operating system

OSF

Open Systems Foundation

OSI

Open System Interface

OSPM

Operating-system-directed power management. A model of power (and system) management in which the operating system plays a central role and uses global information to optimize system behavior for the task at hand.

OSR

OEM service release

OTC

on-tape catalog

OU

Organizational Unit

out

In terms of data flow in kernel streaming and ActiveMovie, indicates production of data. An out pin is compatible with an in pin.

P

packed-pixel frame buffer

A portion of the display memory that holds the contents of a single screen image with screen bits stored in a single plane and with each pixel on the screen having a set of two or more corresponding bits that define the pixel color.

PAD

packet assemblers/disassemblers

PAL format

Phase Alternation Line format. 'The European video standard, except for France. See also NTSC and SECAM.

PAP

password authentication protocol

PBX

private branch exchange

PC

(1) personal computer; (2) packet classifier

PC 97

The 1997-98 requirements for PC system and peripheral design for the "Designed for Microsoft Windows" logo, as defined in PC 97 Hardware Design Guide.

PC 98

The 1998-99 requirements for PC system and peripheral design for the "Designed for Microsoft Windows" logo, as defined in PC 98 Checklist, which is an addendum to PC 97 Hardware Design Guide.

PC Card

A trademark of PCMCIA. A removable device that is designed to be plugged into a PCMCIA slot and used as a memory-related peripheral.

PCI

Peripheral Component Interconnect. A high-performance, 32-bit or 64-bit bus designed to be used with devices that have high bandwidth requirements, such as the display subsystem.

PCM

Pulse code modulation. A method of encoding information in a signal by varying the amplitude of pulses. The most common method of encoding an analog signal into a digital bit stream.

PCMCIA

Personal Computer Memory Card International Association. Sometimes used to refer to a controller for a type of expansion card documented in the PCMCIA standards.

PCT

private communication technology

PDC

primary domain controller

PDL

page description language

PE

Portable EXE

PIC

programmable interrupt controller

PIF

program information file

pin

A set of filter-defined properties in kernel streaming and ActiveMovie that specify a connection endpoint. For example, audio input can be described by a pin on a filter.

PIO

programmed I/O

pixels

An abbreviation for picture element. The minimum raster display element, represented as a point with a specified color or intensity level. One way to measure picture resolution is by the number of pixels used to create images.

planar

See system board.

Plug and Play (PnP)

A design philosophy and set of specifications that describe hardware and software changes to the PC and its peripherals that automatically identify and arbitrate resource requirements among all devices and buses on the system. Plug and Play specifies a set of API elements that are used in addition to, not in place of, existing driver architectures.

Plug and Play BIOS

A BIOS with responsibility for configuring Plug and Play cards and system. board devices during system power up. Provides runtime configuration services for system board devices after startup. See also ACPI.

PnP

Plug and Play

PO

Power management component in kernel

PON

Passive Optical Network

POP

point of presence

port

A connection or socket used to connect a device such as a printer, monitor, or modem-to the computer. Information is sent from the computer to the device through a cable.

port driver

A low-level driver that responds to a set of system-defined device control requests and possibly to an additional set of driver-defined (private) device control requests sent down by a corresponding class driver. A port driver insulates class drivers from the specifics of host bus adapters and synchronizes operations for all its class drivers.

port replicator

Low-cost docking-station substitute intended to provide convenient, one-step connection to multiple desktop devices.

POSIX

Portable Operating System Interface

POST

Power-on self-test. A procedure of the system BIOS that identifies, tests, and configures the PC in preparation for loading the operating system.

POTS

plain old (analog) telephone service/system

power management

Mechanisms in software and hardware to system power consumption, manage system thermal limits, and maximize system battery life. Power management involves trade-offs among system speed, noise. battery life, processing speed, and AC power consumption. Power management is required for some system functions, such as appliance operations (including answering machine, furnace control, and so on).

power policy

For power management, the decisions that determine how to save energy and when to go to sleep, based on end-user preferences, application needs, and system hardware capabilities.

power resources

Resources such as power planes, clock sources, and so on that a device requires to operate in a given power state.

power sources

The battery and AC adapter that supply power to a platform.

PPP

point-to-point protocol

PPTP

point-to-point tunneling protocol

PRI

primary rate interface

program guide

The on-screen user interface that allows users to select, manage, and search television programs and other content-viewing options.

property

In WDM and Windows NT device driver models, an aspect of the device or stream that can be set or retrieved, such as volume level.

property set

In WDM and Windows NT device driver models, a method defined to set and get properties on a driver. Each property set has a unique identifier, which represents types of related information and is used to access the property set.

PS

packet scheduler

PSTN

Public Switched Telephone Network

Px64

Also CCITT Recommendation H.261. A draft standard for motion video compression in videophone and teleconferencing applications, designed for 64-Kbps transmission channels.

Q

QFE

quick fix engineering

QOS

Quality of Service

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.

RAS

remote access service

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.

RAW

read and write

RDR

redirector

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, 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.

RF

radio frequency

RFC

Request for Comments

RFP

request for proposals

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.

RIP

Routing Information Protocol

RIPL

remote initial program load

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-compatible implementations 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.

RMS

root-mean-square

RNA

Remote Network Access

ROM

read-only memory

RPC

remote procedure call

RSA

public-key cipher for encryption/decryption

RSVP

resource reservation Protocol

RTC

real-time clock

RTP

real-time transport protocol

RTS

request to send

S

S/PDIF

Sony/Phillips Digital Interface. The current standard for digital connection to consumer audio devices is the S/PDIF connector. Microsoft is encouraging the use of USB or IEEE 1394 as the digital connection between stereo equipment and PCs rather than adapting S/PDEF to meet PC needs.

sampling

The first step in the process of converting an analog signal into a digital representation. Accomplished by measuring the value of the analog signal at regular intervals (called samples). These values are then encoded to provide a digital representation of the analog signal.

SAP

Service Access Protocol

saturation

The extremes of operating range wherein the output is constant, regardless of changes in input.

scalability

The ability to vary the information content of a program by changing the amount of data that is stored, transmitted, or displayed. In a video image, this translates to creating larger or smaller windows of video on screen (shrinking effect).

scaling

Process of uniformly changing the size of charades or graphics.

SCAM

SCSI Configured Automatically.

SCI

System control interrupt. A system interrupt used by hardware to notify the operating system of ACPI events. The SCI is an active low, shareable, level interrupt.

SCSI

Small computer system interface. Pronounced "scuzzy." An I/O bus designed as a method for connecting several classes of peripherals to a host system without requiring modifications to generic hardware and software.

SCT

Software Compatibility Test

SDE

software development engineers

SDK

Software development kit.

SECAM

Sequential Couleur a Memoire (Sequential Color with Memory). The television standard for France, Russia, and most of Eastern Europe. As with PAL, SECAM is based on a 50-Hz power system but it uses a different encoding process and displays 819 horizontal lines per frame at a scan rate of 25 frames per second (50 fields per second). See also NTSC and PAL format.

sequencer

Hardware or software functionality that interprets a time-stamped music data stream and sends packets to music hardware as their time comes due.

SETP

Stream Environment Transport Protocol

SFF

small form factor

SFS

shared file system

SIGNC

Special Internet Group Name Cache

sink

In terms of device stacking in ActiveMovie, indicates that a pin represents possible connections that are attached to, rather than those that attach. Compare with source.

SIPC

Simply Interactive PC. A vision guiding investments that Microsoft is making in software and hardware advances to make the PC as simple, convenient, and approachable as an appliance.

SIPDIF

Sony/Phillips Digital Interface.

SIR

Serial I

SMART

Self-Monitoring Analysis and Reporting Technology

Smart Battery subsystem

A battery subsystem that conforms to the ACPI requirements and implementation defined in Smart Battery Charger Specification and related specifications.

Smart Battery table

An ACPI table used on platforms that have a Smart Battery subsystem. This table indicates the energy level trip points that the platform requires for placing the system into different sleeping states, plus suggested energy levels for warning the user to transition the platform into a sleeping state.

SMB

server message block

SMBus

A two-wire interface based on the 12C protocol. The SMBus is a low-speed bus that provides positive addressing for devices, as well as bus arbitration.

SMBus interface

ACPI defines a standard hardware and software communications interface between an operating system bus driver and an SMBus controller using an embedded controller.

SMI

System management interrupt. An operating system-transparent interrupt generated by interrupt events on legacy systems. By contrast, on ACPI systems, interrupt events generate an operating-system visible interrupt that is shareable (edge-style interrupts will not work).

SMP

symmetric multiprocessing

SMPTE timecode

An 80-bit standardized edit time code adopted by the Society of Motion Picture and Television Engineers. See timecode.

SMS

1) Microsoft Systems Management Server. Provides a centralized management service for distributed systems. 2) Short messaging service.

SMTP

Simple Mail Transport Protocol

SNA

Software Network Architecture

SNMP

Simple Network Management Protocol

SNR

signal-to-noise ratio (also S/N)

socket services

In Windows, a protected-mode VxD that manages PC Card hardware. Provides a protected-mode PCMCIA Socket Services 2.x interface for use by Card Services. A socket services driver must be implemented for each separate PC Card controller that is used.

software device

A filter in kernel streaming and ActiveMovie that has no underlying hardware associated with it.

software modem

Also host-based signal processing or pumpless modem. Performs signal processing on the host CPU and implements the controller using V.42bis. The modem hardware consists of a telephone-line interface and digital-to-analog and analog-to-digital conversion circuitry. The hardware does not contain a DSP or a microcontroller. Compare with controllerless modem.

Sound Blaster

Hardware produced by Creative Labs, Inc., that represents for MS-DOS-based games one of the major hardware interfaces for both audio and music (specifically MMI) data.

source

In terms of device stacking in kernel streaming or ActiveMovie, indicates that a pin represents possible connections that attach, rather than those that are attached to. Compare with sink.

SPI

Service Provider Interface. Component in Microsoft networking, TAPI, and other communications technologies.

SPID

service profile identifier

spin down

A power-management capability in which a hard drive shuts down its spindle motor.

SPX

Sequenced Packet Exchange

SQL

Structured Query Language

SRC

sample rate converter

SSA

Serial Storage Architecture

SSI

single system image

SSL

secure sockets layer

static

VxD A VxD that is loaded statically during system startup. A static VxD can be loaded in a number of different ways, including device enumeration by the Plug and Play static device enumerator.

static resources

Device resources, such as IRQ signals, DMA channels, I/O port addresses, and memory addresses, that cannot be configured or relocated.

STI

Still Image class in the WDM architecture. The class of filters that deal with still-image capture. A WDM STI minidriver provides support for still-image devices under the WDM still-image architecture.

STI plug-in

In the STI class architecture, a module that manages the translation of standard DDI calls to device-specific sequences in order to support vendor-specific device features.

stream

An object representing an entity on an adapter capable of receiving, processing, or supplying data. Notice that a stream is identical to a WDM Stream architecture pin. A stream can accept data from or supply data to the processor, such as a stream representing an MPEG input or can simply route data through hardware, such as a stream representing an NTSC output jack on the back of an adapter. The purpose of representing nondata hardware with a stream is that the properties of the hardware can be controlled by software.

STS/EN

Status and Enable bits

STT

secure transaction technology

SVC

switched connection

SVD

Simultaneous voice/data. A technology used in TAPI-based modem technology.

SVGA

Super VGA. A video standard established by VESA to provide high-resolution color display on IBM-compatible computers. The most commonly implemented SVGA standard is 1024x768 pixels resolution.

S-Video

Also Y/C video. A video signal that separates the luminance and color (Y and C) components of the signal for improved quality over composite video. The type of video signal used in the Hi8 and S-VHS videotape formats. It transmits luminance and color portions separately, using multiple wires, thus avoiding the NTSC encoding process and its inevitable loss of picture quality.

symmetrical compression

A compression system that requires equal processing capability for compression and decompression of an image. This form of compression is used in applications in which both compression and decompression are used frequently. Examples include still-image databasing, still-image transmission (color fax), video production, video mail, videophones, and video conferencing. Compare with asymmetrical compression.

synchronous

Any operation that proceeds under control of a clock or timing mechanism. Compare with asynchronous.

system board

Also motherboard or planar. The primary circuit board in a PC that contains most of the basic components of the system.

system context

The volatile data in the system that is not saved by a device driver.

system devices

Devices on the system board, such as interrupt controllers, keyboard controller, realtime clock, DMA page registers, DMA controllers, memory controllers, FDC, IDE ports, serial and parallel ports, PCI bridges, and so on. In today's PCs, these devices are typically integrated in the supporting chip set.

T

TAPI

Telephony Application Program Interface. A set of Win32-based calls that applications use to control modems and telephones by routing application function calls to the appropriate service provider DLL for a modem.

TC

Traffic control

TCO

total cost of ownership

TCP

Transmission Control Protocol

TCP/IP

Transmission Control Protocol/Internet Protocol

TDI

transport driver interface

TDMA

time-division multiple access

telephony

Telephone technology. The conversion of sound into electrical signals, its transmission to another location, and its reconversion to sound with or without the use of connecting wires.

TFTP

Trivial File Transfer Protocol

TIA

Telecommunications Industry Association

timecode

For UTEG, frame-by-frame address code time reference recorded on the spare track of a videotape or inserted in the vertical blanking interval. It is an eight-digit number, encoding time in hours, minutes, seconds, and video frames (for example, 02:04:48:26).

TOS

Type of service

Transform

A set in kernel streaming and ActiveMovie that defines the access to a filter actually provided by a pin. Each pin supports one transform.

TSD

type-specific driver

TSPI

telephony service provider interface

TSR

terminate-and-stay-resident

TTL

(1) time to live; (2) transistor-transistor logic

tuple

A data structure defined by the PCMCIA to describe a single, specific characteristic of a PC Card device. Tuples are chained together to form the CIS, which describes to system software the PC Card's resource requirements and other characteristics. Tuples consist of a tuple code, an offset to the next tuple, and a number of bytes specific to the tuple.

TWAIN

API for image acquisition developed by an association of industry leaders. The specification is available from http://www.twain.org.

TXD

transmission data (also XOR)

U

UART

Universal Asynchronous Receiver/Transmitter. A module composed of a single integrated circuit, which contains both the receiving and transmitting circuits required for asynchronous serial communication.

UAS

user account system

UCT

universal coordinated time

UDP

User Datagram Protocol

UHCI

Universal Host Controller Interface

Ul

user interface

UMA

Unified Memory Architecture

UNC

Universal naming convention.

Unimodem

Universal modem driver. A driver level component that uses modem description files to control its interaction with the communications driver, VCOMM.

UP

Uniprocessor (single CPTJ)

UPS

Uninterruptible power supply. A device connected between a computer and a power source that ensures that electrical flow to the computer is not interrupted because of a blackout and, in most cases, protects the computer against potentially damaging events such as power surges and brownouts.

URB

USB request block

URB

USB request block. Clients send URB transfers to the bus by including a pointer in an IRP to a URB structure; a function within the URB identifies the specific request.

USB

Universal Serial Bus. A bidirectional, isochronous, dynamically attachable serial interface for adding peripheral devices such as game controllers, serial and parallel ports, and input devices on a single bus.

USB class

The class of filters under WDM that provides a bus interface and bus enumerator for USB.

User mode

For Windows and Windows NT, the nonprivileged processor mode in which application code executes, including protected subsystem code m Windows NT.

User-mode drivers

Win32-based multimedia drivers and VDDs for MS-DOS-based applications with application-dedicated devices. For more information, see the Multimedia Drivers and Virtual DOS Drivers documentation in the Windows NT DDK.

UTP

unshielded twisted pair

V

VAR

Value added reseller. A company that resells hardware and software packages to developers and/or end users.

VAR

value-added retailer

VBI

Vertical blanking interval. The time interval between television fields needed for the scanning gun to move from the bottom to the top of the screen for the start of the next field.

VC

virtual circuit

VCACHE

In Windows, a 32-bit protected-mode cache driver.

VCDFSD

virtual CD-ROM file system driver

VCI

virtual channel identifier

VCOMM

In Windows, a 32-bit protected-mode communications driver.

VCR

Video cassette recorder . An analog magnetic recording and playback machine. Usually used for recording and viewing full-motion video; also useful as a data backup device.

VDD

Virtual display driver.

VDM

(1)virtual DOS machine; (2) virtual device manager (Windows NT)

VDMA

Virtual Direct Memory Access

VDMAD

virtual DMA device

vector graphics

Images defined by sets of straight lines, defined in turn by the locations of the end points.

VESA

Video Electronics Standards Association. The governing body that establishes standards for the video and graphics portions of the electronics industry.

VFW

Video for Windows

VGA

Video graphics array. A video adapter that supports 64Gx480-pixels color resolution. Video display standard for boot devices under Windows operating systems. Provides medium-resolution text and graphics.

video codecs

Full-color video. Requires 3 bytes per pixel, at 64Ox480 resolution; equals nearly I MB of digital data per frame. This means that a developer could easily use 1 GB of hard-disk space by storing less than one minute of uncompressed digital video information.

VLM

NetWare 4.x client shell

VM

Virtual machine. Software that mimics the performance of a hardware device. For example, a software program that allows applications written for an Intel processor to be run on a Motorola chip interprets the Intel machine instructions, becoming a virtual Intel machine.

VPE

Video Port Extensions. Extensions to the DirectDraw API to control the video stream from the video port within the context of VGA memory.

VPI

virtual path identifier

VPICD

virtual programmable interrupt controller device

VPN

Virtual Private Network

VRAM

video RAM

VRML

virtual reality modeling language

VSD

vendor-supplied driver

VUDA

VESA Unified Graphics Architecture

VxD

Virtual Device Driver. A device driver that runs at the privileged ring 0 protected mode of the microprocessor. Can extend the services of the Windows kernel, supervise hardware operations, or perform both functions. Such driver files are usually named according to the scheme VxD, where x refers to the device or service supported.

W

W3C

World Wide Web Consortium

WAN

Wide area network. A communications network that connects geographically separated areas. Compare with LAN.

warm docking

A method of removing or installing a mobile system in a docking station with which the computer can be docked or undocked while in a reduced power state, such as suspend.

WBEM

Web-based Enterprise Management. Technology under development by BMC Software, Inc., Cisco Systems, Inc., Compaq Computer Corporation, Intel Corporation, and Microsoft Corporation, based on standards being developed by DMTF and IETF, to provide a mechanism to specify information exchange between management applications and managed components.

WDCTRL

Western Digital-compatible hard disk controller

WDL

Windows Driver Library. See WHQL.

WDM

Win32 Driver Model. A 32-bit driver model based on the Windows NT driver model that is designed to provide a common architecture of I/O services and binary-compatible device drivers for both Windows NT and Windows operating systems for specific classes of drivers. These driver classes include USB and IEEE 1394 buses, audio, still-image capture, video capture, and HID-compliant devices such as USB mice, keyboards, and joysticks. Provides a model for writing kernel-mode drivers and minidrivers, and provides extensions for Plug and Play and power management.

WDM Comm

WDM Communications Class

WDM DDK

Provides the supplementary header files used together with the Windows NT DDK to build WDM drivers.

WDM power management

Facilities provided in WDM for drivers to implement power policy and control. DDIs are defined for synchronizing power state changes with other power management activities in the system and for detecting device idleness. IRPs are defined for setting power sate, enabling wakeup, and querying power status.

WDM streaming

A WDM-based kernel-mode extension of Microsoft ActiveMovie, providing kernel connection and streaming services as used by the WDM Stream class driver and system software components provided in future versions of the Windows and Windows NT operating system, such as the cross-process audio mixer and sample rate converter. WDM streaming provides low-level services for the lowest latency streaming; ActiveMovie provides higher-level features. Operating system support includes a Stream class driver that supports minidrivers for audio, video, and other types of stream input output, and acceleration.

WDMCSA

WDM Connection and Streaming Architecture

WfM

Wired for Management

WHQL

Windows Hardware Quality Laboratory. Formerly Microsoft Compatibility Labs. Provides compatibility testing services to test hardware and drivers for Windows and Windows NT. Administers testing for the "Designed for Microsoft Windows" logo programs. Information: http://www.microsoft.com/hwtest/.

Win32 API

A 32-bit application programming interface for both Windows and Windows NT that includes sophisticated operating-system capabilities, security, and API routines for Windows-based applications.

Windows

Refers to the Microsoft Windows 95 operating system, including any add-on capabilities and any later versions of the operating system.

Windows NT

Refers to the Microsoft Windows NT version 4.0 operating system, including any add-on capabilities and any later versions of the operating system, unless specific design issues are defined that relate to version 5. O.

Windows NT DDK

Supports Windows NT, provided through MSDN Professional membership. Documents the Windows NT driver model (upon which WDM is based) and is an essential component for building WDM drivers.

Windows NT driver model

The layered device driver model used under the Windows NT operating system. For information, see Inside Windows NT, by Helen Custer (Microsoft Press, 1993).

WinHEC

Windows Hardware Engineering Conference

WINS

Windows Internet Name Service

WinSock

Windows Sockets

WMI

Windows Management Instrumentation. Extensions to WDM being developed for Windows NT 5.0 and Windows "Memphis" to provide an operating system interface through which instrumented components can provide information and notifications.

workstation

In general, a powerful computer with considerable calculating and graphics capability.

WOSA

Windows Open System Architecture

WSP

WinSock Proxy

WWW

World Wide Web

WYSIWYG

what you see is what you get

X

XDSL

general class of DSL technologies

XMS

extended memory

XOR

Exclusive OR- A Boolean operation that yields "true" if and only if one of its operands is true and the other is false. Compare with OR.

Y

YcrCb

See YUV.

YUV

The method of color encoding for transmitting color video images while maintaining compatibility with black-and-white video. Uses less bandwidth than the three separate video signals in an RGB video transmission. Consists of two major components: luminance (Y), which corresponds to the brightness of an image pixel, and chrominance (UV or CrCb), which corresponds to the color of an image pixel.

Z

Z

Z axis. For graphical displays, the optical axis that is perpendicular to X and Y axes.

ZAK

Zero Administration Kit

ZAK

Zero Administration Kit for Windows NT Workstation. A set of tools, methodologies, and guidelines for IT Managers and OEMs that incorporates and supplements existing Windows NT technologies to allow for simplified implementation of a secure, policy-based management.

ZAW

Zero Administration Windows. A Microsoft initiative that focuses on improving Windows and Windows NT for maximum automation of administrative tasks with centralized control and maximum flexibility.

ZIPI

A MIDI-like serial data format for musical instruments. Provides a more hierarchical method of addressing instruments and an extensible command set.

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