V A| B| C| D| E| F| G| H| I| J| K| L| M| N| O| P| Q| R| S| T| U| V| W| X| Y| Z| Numerical Listing| V.34 High-speed modem standard, also known as V.Fast, governing speeds up to 28,800 bps as set by the International Telecommunications Union. V.42 International Telecommunications Union standard for error correction VAN (Value-Added Network) A private network through which value-added carriers provide special data transmission services. VAR (Value-Added Reseller) A company that writes application software that is packaged and sold with underlying systems software (often including a database management system) and hardware. An organization that buys equipment from a vendor at a discount, adds value (such as application software that is packaged and sold with underlying systems software, often including a database management system) and remarkets it. VAX (Virtual Address Extension) The Digital architecture that was the company’s principal product line prior to the Alpha. VAX was enormously successful in DEC’s traditional engineering and scientific customer base and, more significantly, enabled DEC to penetrate the commercial data processing and office automation markets. TOP OF PAGE Vector Facility An attachment to a processor that enables the processor to run programs that issue vector instructions. Vector instructions are particularly useful in scientific calculations, but are not particularly useful for database operations. Vendor Neutral A state in which no one vendor can control the definition, revision or distribution of a specification. Vendor-neutral specifications encourage the development of competing yet compatible implementations, freeing the purchaser to choose from a multitude of vendors without suffering a loss of functionality. Vendor-neutral specifications must be comprehensive, consistent, and either publicly available or licensed at a nominal fee. Additionally, they must be defined by a multilateral association that is representative of a broad cross-section of the computer industry, open to new members, publishes the rules of membership and operates according to democratic principles. Preferably, a vendor-neutral specification is supplemented with at least one reference implementation. This reference would be available in a format that allows recreation — that format would be source code for software implementations — and a set of conformance tests that sufficiently assure the implementation’s integrity under all reasonable conditions of projected use. VGA (Video Graphics Array) A hardware display and software resolution standard for personal computers. VHDL (VLSI Hardware Description Language) An industry standard format for describing integrated circuit logic and behavior. TOP OF PAGE VIDA (VAX IBM Data Access) Digital Equipment Corp.’s Rdb to DB2 interoperation software. View An alternative representation of data from one or more tables. A view can include all or some of the columns in these tables. VINES Banyan’s network operating system. Virtual Circuit In packet switching, network facilities that appear to users to be an end-to-end circuit, but are in fact a dynamically variable network connection in which sequential user data packets may be routed differently during the course of a "virtual connection." Transmission facilities may be shared by many virtual circuits simultaneously. VITAL (VHDL Initiative for the Standardization of ASIC Libraries) A standard for defining the format of integrated circuit simulation libraries. VLSI (Very Large Scale Integrated Circuit) Generally contains more than 10,000 logic gates. TOP OF PAGE VM (Virtual Machine) The IBM VM set of operating system products (VM/SP, VM/HPO, VM/XA, VM migration and VM/ESA) manages a system so that all its resources — processors, storage and I/O devices — are available to many users at the same time. Each user has at his disposal the functional equivalent of a real dedicated system. Because this functional equivalent is simulated by VM and does not really exist, it is called a "virtual" machine. VMEbus A high-speed parallel backplane system bus originally developed by Motorola, and now widely used on technical workstations and small multiuser systems. VMS (Virtual Machine Storage) Digital’s traditional mainstay operating system. VAX computers that plays a role for DEC similar to the one Multiple Virtual Storage plays for IBM. Voice-Grade Channel A channel with bandwidth equivalent to a telephone line obtained through the public telephone network. The maximum potential bandwidth of a voice-grade channel is approximately 20 KHz; however, most voice grade channels in a transmission facility are usually spaced 4,000 Hz apart, and not all of that bandwidth is generally available to a user due to the presence of noise-limiting loading coils. The telephone network itself is usually defined in terms of channels, with frequencies from 300 to 3,400 Hz. VPA (Volume Procurement Amendment) An agreement between a computer vendor and a customer under which the vendor grants discounted prices in return for the customer’s commitment to purchase a minimum quantity of products. VSAM (Virtual Storage Access Method) IBM’s chosen access method for direct access files. It is optimized for a virtual storage environment. Multiple Virtual Storage, Data Facility Product, Information Management System, Customer Information and Control System, and Database-2 all use VSAM. TOP OF PAGE VSAT (Very Small Aperture Terminal) Small earth station for data transmission to and from orbiting satellites. VSE (Virtual Storage Extended) VSE (formerly DOS/VSE) is a multitasking, 370-architected operating system akin to Multiple Virtual Storage (MVS). VSE work runs in partitions rather than address spaces, and uses POWER for input/output rather than JES, but is largely similar to MVS. Subsequent VSE/ESA releases gave VSE the XA-370 channel architecture, 31-bit virtual and real storage support, and data spaces. VSE is the IBM operating system on one-third of installed 4381s and a significant proportion of 9370s as well. It offers transaction and batch processing capabilities well beyond Virtual Machine’s current capabilities, and has a close affinity with MVS. VTAM (Virtual Telecommunications Access Method) The main Systems Network Architecture subsystem resident in an IBM mainframe that manages session establishment and data flow between terminals and application programs, or between application programs. VTOC (Volume Table of Contents) The data structure on a direct access volume that describes each data set on that volume. TOP OF PAGE VUP (VAX Unit of Performance) The average compute-bound performance of a VAX processor relative to a VAX-11/780. One VUP is equivalent to between 0.7 and 1.0 IBM System/370 MIPS, depending on the compute-bound benchmarks chosen. Multiuser benchmark results vary much more widely, due to different input/output architectures and software path lengths on Digital Equipment Corp. and IBM systems. Comments? Questions? Entire contents Copyright © 1997, 1998 by Gartner Group, Inc. All rights reserved. Reproduction of this publication in any form without prior written permission is forbidden. 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