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S, T, U, V, W & X |
Scanner : A device that resolves a two-dimensional object, such as a business document, into a stream of bits by raster scanning and quantization.
SCO : Santa Cruz Operation. Supplier of the popular SCO Unix operating system for Intel-based system and a founding member of the Advanced Computing Environment consortium.
Screen capture (Capture d'‰cran) : Operation consisting in "photographing" the computer display and copying the result in a file on disk.
Sector (Secteur) : Recording zone on a disk. Of a fixed size, the sectors are the smallest addressable units on a disk. A sector generally contains 512 data bytes.
SCSI : Small Computer System Interface. A peripheral interface for up to seven devices. SCSI provides a high-speed, parallel data transfer of up to 4 Mbytes per second and has the advantage of connecting multiple peripherals while taking up only one slot in the computer.
SCSI chain : Up to seven SCSI peripherals can be serially connected to the same computer SCSI port.
Separator (S‰parateur) : Special character in charge of delimiting words or values. This separator is not part of the character string it delimitates.
Serial interface (Port s‰rie) : Interface allowing to exchange data in serial mode : in this mode one bit is exchanged at a time. On a micro computer, used for example for modem interface. To be opposed to "parallel interface".
Server : A system or a program that receives requests from one or more client systems or programs to perform activities that allow the client to accomplish certain tasks. A processor that provides a specific service to systems on a network. Routing servers connect subnetworks of like architecture, gateway servers connect networks of different architecture by performing protocol conversions and terminal, printer and file servers provide interfaces between peripheral devices and systems on the network.
Sex : This topic is definitely outside the scope of the present glossary, sorry.
SGML : Standard Generalised Markup Language. An international standard of identifying the basic structural elements of a text document. SGML addresses the structure of a document, not its format or presentation.
Shell : Intermediate program between the user and a software. The MS/DOS shell allows to choose files in a list and to start commands by selecting them in menus.
SIMM : Single In-Line Memory Module. Small board containing 8 or 9 memory chips. These boards are used to increase the storage capacity.
Simple Network Management Protocol (SNMP), Agent : A platform that uses a Transmission Control Protocol/Internet Protocol stack to generate SNMP-compliant information, which is then used by an SNMP " manager" to manage the supported platform.
Socket services : Universal software interface which manages PCMCIA cards supports.
SONET : Synchronous Optical Network Standard. An emerging International Telegraph and Telephone Consultative Committee (CCITT) standard for synchronous transmission up to multigigabit speeds. The standard promises multivendor interoperability, improved troubleshooting and network survivability. As a Layer 1 standard, it will be the foundation for broadband ISDN (Integrated Services Digital Network)
SPX : Sequenced Packet eXchange. A network protocol from Novell.
SQL : Structured Query Language. SQL is a relational data language that provides a consistent, English keyword-oriented set of facilities for query, data definition, data manipulation and data control. It is a programming interface to a relational database management system (RDBMS). SQL was introduced by IBM Research as the main external interface to System R, an experimental RDBMS developed in the 1970s. SQL statements include: Data manipulation language (DML) statements - SELECT, INSERT, UPDATE and DELETE; Data definition language (DDL) statements including the CREATE and DROP statements for tables and indexes and statements that control data consistency, and grant and revoke authority. SQL statements that are not completely specified until the program is executed are called dynamic. SQL statements that are completely specified when the program is compiled are said to be static.
SRAM : Static RAM. This memory, contrarily to the DRAM, does not need to be refreshed. Data registered in SRAM are maintained until they are modified.
Start/stop bits : Signalisation bits affected to a character before its transmission in asynchronous mode.
Store-and-Forward : A delivery method for data within a network in which information moves from one node to another toward its target. If any node in the paths is unavailable, the last active node in the chain holds the information until that node becomes available, at which time the transfer continues. The originator need not maintain the information as each node receiving the object accepts responsibility for its delivery. Although store-and-forward is most often associated with electronic mail, it can be used for file transfer, software updates and other functions that do not require a "quick" or synchronised response.
Switched Connection : A connection that requires a manual or an automated sequence to establish a connection before it can be used by any software or hardware component. Often referred to as a "dialled" connection because of the need to complete a phone call to establish the connection, its characteristics are different from a dedicated line (always available for use) and it requires different support. Applications using switched lines cannot assume the connection is made or that communication has been initialised.
Synchronous (Synchrome) : Having a constant time interval between successive bits, characters or events. Synchronous transmission uses no redundant information to identify the beginning and the end of the characters, and thus is faster and more efficient than asynchronous transmission, which uses start and stop bits. The timing is achieved by transmitting sync characters prior to data ; usually synchronisation can be achieved in two or three character times.
System V : (Read as system 5). AT&T 's Unix operating system, introduced in 1983, then sold to Novell.
Systimax : AT&T cabling system.
TFT : Thin layer Transistor. Transistor type used in active matrix screens in laptop computers. Layers of TFT and condensers are put on a glass containing RGB filters.
TCP/IP : Transmission Control Protocol/Internet Protocol. TCP/IP is a set of protocols for Layers 3 an 4 of the seven-layer Open Systems Interconnection network model. These are, respectively, the network and the transport layers. TCP/IP has been developed under the auspices of the Department of Defence. It has achieved de facto standard status, particularly as higher-level layers including IBM, Digital Equipment Corp., AT&T, Apollo, Data General and Sun Microsystems. But its exclusion from Systems Application Architecture means that IBM views TCP/IP as a special-purpose protocol set. The biggest issue for TCP/IP is potential migration to the International Standards Organisation protocols for Layers 3 and 4.
Token Ring (Anneau € jeton) : LAN topology and access method promoted by IBM. Curiously invented for dumb terminal connection purpose, this architecture has been definitely outdated by Ethernet.
TPC-A : Transaction Processing Performance Council. A revised and superior version of the debit/credit on-line transaction processing (OLTP) benchmark. The major improvements in TPC-A were the requirements for full disclosure and the inclusion of the front-end network and terminals. TPC-A is intended to replace debit/credit as the only industrywide measure for OLTP performance and price/performance. It is good test since it measures end-to-end performance, but it still is only one test reflecting a single type of transaction.
Tps : transactions per second. The metric used in evaluating on-line transaction processing system performance. Tps are typically measured under conditions of a specified percentage of standard transactions completed in under a specified response time.
Track (Piste) : Circular recording zone on a diskette or hard disk. Tracks generally are generally composed of sectors.
Transaction : A logical update that takes a database from one consistent state to another.
Transport Layer (Couche Transport) : In the Open Systems Interconnection (OSI) model, the network processing entity responsible, in conjunction with the underlying network, data link and physical layers, for the end-to-end control of transmitted data and the optimized use of network resources.
Two-Phase Commit : Method for co-ordinating a single transaction across two or more database management systems or other resource managers. Two-phase commit guarantees the logical integrity of data by ensuring that transaction updates are finalised ("committed") in all of the separate databases or are fully backed out of all participating databases, i.e., all or nothing based on transaction boundaries. Two-phase commit is a necessary component of distributed database and is implemented in "transaction management" software, which may be part of a database management system, on-line transaction processing monitor, or front-end application tool.
Unix : A family of operating systems known for its relative hardware independence and portable applications interface. This time-sharing operating systems is available on all AT&T computers, and is widely used in technical and scientific computing applications. It has recently made great strides in entering mainstream commercial computing. Unix System V is the version of Unix supported by AT&T and its user group, Unix International.
UPS : Uninterrupted Power Supply. Battery fed unit which supplies electricity to the computer in case of mains failure.
USL : Unix System Laboratories. USL, which develops and markets the Unix System V operating system, the Tuxedo Enterprise Transaction Processing System and other standards-based system software products, started in 1991 as a subsidiary spun off from AT&T. Novell acquired USL in December 1992, partially as a counter to Microsoft and its Windows products. The announcement virtually set the stage for the next-generation operating system war. Novell, which is likely to better integrate NetWare servers with Unix, seeks to achieve three goals: expand its market share, reduce its losses to Windows NT, and accelerate the expansion of Unix, the low-end commercial market.
UTP : Unshielded Twisted Pair. It is guaranteed by AT&T not only for speed capacity but also for application usage. Easy to mount and rather cheap, insensible to electromagnetic disturbances, it is able to sustain 100 Mbps speed on distance less than 100 meters.
VDISK : Refer to "Virtual Disk".
Vectorial font : Vectorial fonts handle the characters by representing their shape, thus being independent of the actual size. Contrarily, character set generated using a method which handles each character as a pixel set are called bitmap fonts.
VGA : Video Graphics Array. A hardware display and software resolution standard for personal computers.
Virtual disk (Disque virtuel) : Main storage section configured as a disk unit, thus allowing faster read and write operations. Also called "VDISK" or "RAM disk".
Virus : Hidden program whose scope is to damage the programs on which they graft. Viruses generally are copied when loading a program in storage. They multiply themselves and damage other files. Secondary effects can be disastrous.
VLSI : Very Large Scale Integration. Generally contains more than 10,000 logic gates.
VRAM : Video RAM. DRAM used for high performance display.
WAN : Wide-Area Network. A data transmission facility that connects geographically dispersed sites using long-haul networking facilities.
WIMPS : Windows, Icons, Menus, Pointers, Scroll Bars. A style of graphical user interface originally developed by Xerox and popularised by Apple Macintosh
Windowing : A display technique that uses multiple screen segments to display different items of information. The display can take two forms: tiling ( breaking up the screen into discrete segments) and overlapping (producing a three-dimensional effect by having a screen segment partially or fully obscure another segment)
Windows : Microsoft graphical environment, allowing to use simultaneously several applications, to exchange information between applications, and file management.
Wollongong : US company specialised in communication software.
WORD : MicrosoftÆs text management software.
WORM : Write Once, Read Many. A digital, optical storage medium on which information can be recorded one and read many times. Provides for extremely compact storage of data at relatively low prices compared to traditional magnetic storage.
X-Windows : The software system written for managing windows under Unix. A graphics architecture, application programming interface and prototype implementation developed by the Massachusetts Institute of Technology. X-Windows defines a client/server relation between the application program and the workstation. It is not, however, a complete graphical user interface, but rather the basis upon which one can be built.
X.25 : An International Telegraph and Telephone Consultative Committee interface standard for connection of data terminal equipment to a public packet-switching network. X.25 defines the services that the user can expect from a public packet-switching network, including the establishment of virtual circuits through the network to exchange packets with other users.
X.400 : The International Telegraph and Telephone Consultative Committee series of recommendations that defines the basis for providing Message Handing Services, such as store-and-forward electronic mail.
X.500 : The International Telegraph and Telephone Consultative Committee standard for directory services.
X/Open : An international consortium of computer vendors that aims to create and promote a vendor-independent interface standard called the Common Applications Environment (CAE). CAE addresses the operating system interface., data management and languages, and will include networking and will include networking and a graphic user interface. X/Open was founded in Europe by European vendors, but has expanded to include a number of US companies (AT&T, Digital Equipment Corp., Hewlett-Packard, NCR, Unisys and Sun Microsystems ) and office in the United States.
XPG : X/Open Portability Guide. A set of standards and practical advice about how to design open computer systems from X/Open; a specification for compliance with X/Open's Common Application Environment.
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