C

cache

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

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.

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.

CDFS

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

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.

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.

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.

CI

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

CIE

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

CIS

Card information structure.

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.

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.

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.

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.

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.

CSA

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

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.