Glossary of Acronyms

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V.23 A CCITT standard for modem communications at 1200 or 600 bps with a 75-bps back channel. Used in the United Kingdom for some video text systems.

V.25 A CCITT standard for modem communications that specifies an answer tone different from the Bell answer tone used in the U.S. and Canada. Most intelligent modems can be set with an ATBO command so that they use the V.25 2100 Hz tone when answering overseas calls.

V.32 A CCITT standard for modem communications at 9600 bps and 4800 bps. V.32 modems fall back to 4800 bps when line quality is impaired and fall forward again to 9600 bps when line quality improves. The actual transmission rate is 2400 baud using QAM (quadrature amplitude modulation) and optional TCM (trellis-coded modulation) to encode as much as 4 data bits per baud.

V.32bis A CCITT standard that extends the standard V.32 connection range and supports 4800-, 7200-, 9600-, 12000-, and 14400-bps transmission rates. V.32bis modems fall back to the next-lower speed when line quality is impaired, fall back further as necessary, and fall forward to the next-higher speed when line quality improves. The actual transmission rate is 2400 baud using QAM (quadrature amplitude modulation) and TCM (trellis-coded modulation) to encode as much as 6 data bits per baud.

V.32turbo A proprietary standard proposed by several modem manufacturers that will be cheaper to implement than the standard V.32 fast protocol, but which will only support transmission speeds of up to 18800 bps. Because it is not an industry standard, it is not likely to have widespread industry support.

V.34 A CCITT standard that extends the standard V.32bis connection range, supporting 28800 bps transmission rates as well as all the functions and rates of V.32bis. Products following this standard are now available. This was called V.32fast or V.fast while under development.

V.42 A CCITT standard for modem communications that defines a two-stage process of detection and negotiation for LAPM error control. Also supports MNP error-control protocol, Levels I through 4.

V.42bis An extension of CCITT V.42 that defines a specific data-compression scheme for use with V.42 and MNP error control.

VCPI - Virtual Control Program Interface. A 386 and higher processor memory management standard created by Phar Lap software in conjunction with other software developers. VCPI provides an interface between applications using DOS extenders and 386 memory managers.

VESA - Video Electronics Standards Association. Founded in the late 1980s by NEC Home Electronics and eight other leading video board manufacturers with the main goal of standardizing the electrical, timing, and programming issues surrounding 800X600 resolution video displays, commonly known as Super VGA. VESA has also developed the Video Local Bus (VL-Bus) standard for connecting high-speed adapters directly to the local processor bus.

VGA - Video Graphics Array. The original standard for the current generation of video monitors and cards. It supports 640 by 480 pixels on the CRT screen, and 16 or 256 different colors. It has been replace by the SVGA and XVGA (Extended Video Graphics Array).

VL - VESA Local Bus. Local bus standard for a bus that allows high speed connections to peripherals.

VLB - VESA Local Bus. . Local bus standard that allows high speed connections to peripherals. A 32-bit bus which allows bus mastering, and uses two cycles to transfers a 32-bit word, peaking at 66 Mb/sec. It also supports burst mode, where a single address cycle precedes four data cycles, meaning that 4 32-bit words can move in only 5 cycles, as opposed to 8, giving 105 Mb/sec at 33 MHz. The speed is mainly obtained by allowing VL-Bus adapter cards first choice at intercepting CPU cycles. It's not designed to cope with more than a certain number of cards at particular speeds; e.g. 3 at 33, 2 at 40 and only 1 at 50 MHz, and even that often needs a wait state inserted. VL-Bus 2 is 64-bit, yielding 320 Mb/sec at 50 MHz. There are two types of slot; Master and Slave. Master boards (e.g. SCSI controllers) have their own CPUs which can do their own things; slaves (i.e. video cards) don't. A salve board will work on a master slot, but not vice versa. Normally used for video adapters, VESA remains largely a display standard. The VLB became popular at the start of 1993. The VLB is now obsolete.

VM - Virtual Machine. A complete MS-DOS environment and a console in which to run an MS-DOS based application or Windows 16-bit applications. A VM establishes a complete virtual x86 (that is, 80386 or higher) computer running MS-DOS. Any number of VM's can run simultaneously. Also known as a virtual DOS machine.

VMM - Virtual Memory Manager. A facility in Windows enhanced mode that manages the task of swapping data in and out of 386 and higher processor virtual real mode memory space for multiple non-Windows applications running in virtual real mode.

VRAM - Video Random Access Memory. VRAM chips are modified DRAMs on video boards that enable simultaneous access by the host system's processor and the processor on the video board. A large amount of information thus can be transferred quickly between the video board and the system processor. Sometimes also called dual-ported RAM.

VSF - Vertical Scanning Frequency. Same as refresh rate. Measures how many times a second the entire screen is redrawn, or refreshed, on the monitor. The higher the vertical refresh (in MHz), the less flicker. An interlaced monitor only scans every other line each time the screen is refreshed. A non interlaced monitor scans every line each time the screen is refreshed.

VX - . The Intel Triton III motherboard chip. The VX supports DIMMs.

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Compiled by Scott McArdle, MagnaCom Limited. I hope this list has helped you and if there is an item that should be on this list, please let me know. Thanks. PS, I've spent 100's of hours maintaining this list, please don't be a LAMER.