G, H, I, J & K


G

GaAs : Gallium Arsenide. A semiconducting material characterised by extremely fast switching times for transistors. The material also consumes relatively low power. In the early 80s, this material was thought to replace silicon. Research investment on this material has now lowered.

Gateway : A physical or logical network station that interconnects two otherwise incompatible networks, network nodes, subnetworks, or devices. Gateways perform protocol-conversion operations across a wide spectrum of communications functions or layers.

Giga : Prefix corresponding to a one billion quantity. One GB (Giga-Bytes) is equal to 1,000 MB or 1,000,000 KB or 1,000,000,000 Bytes. In 1995, disk storage have a capacity expressed in GB : generally between 0.2 and 4 GB.

Graphical accelerator (Acc‰l‰rateur graphique) : Specialised component in charge of processing graphical data display instead of the CPU. Mainly used for workstations large screens display.

Grey levels (Niveau de gris) : Scale of grey varieties between the black and the white. Graphical software generally propose 16 or 256 grey levels.

Groupware : "Groupware" was originally coined to describe a new class of applications designed to provide electronic support for groups of individuals working together toward a common goal. In the last several years, the term has been applied to applications ranging from unstructured electronic mail to rigorously structured work-flow systems. Groupware is more useful as a concept when it is broken down into three major stages : communication, coordination and cooperation. In this light, groupware applications can be viewed in terms of the degree of structure in the group interaction and in complexity of that structure, and the rigor with which the activity itself is monitored.

GUI : Graphical User Interface. A generic user interface. Examples of a GUI include Unix International's OpenLook, the Open Software Foundation's Motifs and Apple Computer's Macintosh interface. A comprehensive GUI environment has four components :

  1. a graphics library, which provides a high-level graphics programming interface
  2. a user interface toolkit - built on top of the graphics library - that provides applications programs with mechanisms for creating and managing the dialog elements (a.k.a. widgets) of the WIMPS (windows, icons, menus, pointers, scroll bars) interface, including the window manager
  3. a user interface style guide, which specifies how applications should use the dialog elements to present a consistent, easy-to-use environment (i.e., "feel") to the user
  4. application program conformance with a single user-interface style effectiveness and user productivity.

H

Hard disk units (Unit‰s de disques durs) : Direct access storage unit containing unmovable disks. The hard disks are composed of metallic circular plates, covered with a magnetic layer allowing data recording. They are sealed in a box. Synonymous of "Fixed Disk".

Hayes compatible modem : Modem using the Hayes command set.

Help : System function allowing the user to obtain information about the computer or the program being executed.

Hertz (Hz) : Frequency unit internationally used. One Hz equals one cycle per second.

Hewlett-Packard (HP) : Hewlett-Packard Corporation, Palo Alto, California. Computer manufacturer, second largest income in 1994. Rather successful, mostly in the server and printer markets.

HP : Hewlett-Packard Co., Palo Alto , Calif.

HP-UX : Hewlett-Packard's System V-based Unix implementation, with real-time extensions added.

HSM : Hierarchical Storage Manager. Software aiming at managing mass storage data in order to let very active data reside on hard disk, and to migrate less active data from/to less expensive storage such as tape units.

Hub : In a 10-Base T LAN topology , passive component connecting a group of stations, connected in point-to-point mode to the Hub, to the LAN.

Hypertext : Software technology used to create and store simple and complex navigational paths across computerised data, thus allowing through mouse click to navigate easily in the data.

Hz : Hertz. A measure of electromagnetic frequency. One Hz equals one cycle per second.

I

I/O : Input/Output. The activity of sending information to or from devices, terminals, DASDs (direct access storage devices), tape drives and printers. Physical I/O performance lags that of memory and logical technologies.

IBM : International Business Machine Corporation. Premier computer manufacturer. After dominating the market until the end of the 80s, IBM is today facing difficulties.

Icon (IcŸne) : A symbol of pictorial representation of an object or idea in graphical user interfaces, used to represent the different functions or applications available to the user. A mouse is typically used to select the desired operation by pointing to one of the icons on the screen.

ICR : Intelligent Character Recognition. A technology that employs either software only or software and hardware to automatically recognise and translate raster images into structured data.

IDE : Integrated Device Electronics. Control electronic circuits embedded on a hard disk according to a specific interface.

IEEE : Institute of Electrical and Electronics Engineers. Organisation of engineers, scientists and students involved in electrical, electronics and related fields ; also functions as a publishing house and standards-making body.

IEEE 802.3 : The physical and medium access control standards developed by the Institute of Electrical and Electronics Engineers for CSMA/CD (Carrier sense Multiple Access with Collision Detection) local-area networks, such as Ethernet.

Interface : Transfer channel allowing communication between different elements inside a computer, between different computers, between a computer and an external equipment, or between different programs.

Internet : World largest network, on which tens of thousands of servers and tens of millions of workstations are connected. It is not centrally governed : anyone can create data accessible to the whole users community.

Interruption : Signal sent to a processor to invite it to interrupt the operation in progress, to allow to proceed to another operation.

Integrated circuit (Circuit int‰gr‰) : Electronic circuit engraved on a semi-conductor material, most generally crystalline silicon.

IRQ : Interruption ReQuest. Same as "Interrupt" for PC systems.

ISA : Industry Standard Architecture. It is a PC architecture based upon three key elements : an 8088 Intel microprocessor, MS-DOS operating system, and an 8 bit I/O bus.Historically, this "standard" has been defined by IBM in its famous PC (in 1981) ; IBM always denied to publish the specifications, and the competitors had to discover them (it was not tricky enough to resist to skill, patience and oscilloscopes) in order to be able to manufacture compatible PCBs, and lastly compatible PCs.

IPX : Internetwork- Packet eXchange. A local-area network transport protocol often found in Novell's family of Net Ware network operating systems.

ISDN : Integrated Services Digital Network. The technical standards and design philosophy according to which digital networks will be designed. ISDN provides high-speed, high-bandwidth channels to every subscriber on the network, achieving end-to-end digital functions with standard equipment interface devices. The network will enable a variety of mixed digital transmission services to be accommodated at a single interface (including voice and circuit and packet-switched data). Access channels under definition include basic (144 Kbps, or 2B+D) and primary (1.544 Mbps or 23B+D in North America, and 30B+D, or 2.048 Mbps in Europe) interface rates. Signalling System 7 (SS7), an out-of-band signalling scheme, is key to current ISDN implementation; the International Telegraph and Telephone Consultative Committee (CCITT) general assembly finalised a variant, CCITT n— 7, in 1988.

ISO : International Standards Organisation. A voluntary, non-treaty organisation established in 1949 to promote international standards.

ISO/OSI Model : International Standards Organisation/Open System Interconnection. A standard, modular approach to network design that divides the required set of complex functions into manageable, self contained, functional layers. These layers, from the innermost, are :

  1. Physical Layer - concerned with the mechanical and electrical means by which devices are physically connected and data transmitted
  2. Link Layer - concerned with how to move data reliably across the physical data link
  3. Network Layer - provides the means to establish, maintain and terminate connections between systems. Concerned with switching and routing information
  4. Transport Layer - concerned with end-to-end data integrity and quality of service
  5. Session Layer - standardises the task of setting up a session and terminating it. Coordinates the interaction between and application processes
  6. Presentation Layer - relates the character set and data code that are used to the way data is displayed on a screen or printer
  7. Application Layer- concerned with the higher-level functions that support application or system activities.

IWS : Intelligent Workstation. A term synonymous with programmable workstation. A personal computer.

J

JPEG : Joint Photographic Experts Group. A widely accepted, international standard for compression of color images.

K

Keyboard (Clavier) : Main input organ on PCs. Generally composed of 102 multi-fonction keys : used in conjunction with the Upper Case, Ctrl and Alt keys, it provides more than 250 elementary commands.

Khorn-Shell : UNIX shell .


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