V

VAR

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

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.

VCACHE

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

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.

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.

VGA

Video graphics array. A video adapter that supports 640x480-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 640x480 resolution; equals nearly 1 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.

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.

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.