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O, P, Q & R |
OCR : Optical Character Recognition. The ability of a computer to recognise written characters through some optical-sensing device and pattern recognition software.
ODA : Open Document Architecture. An international standard that enables users to exchange text and graphics generated on different types of office products.
ODBC : Open Database Connectivity. An interface based on the Structured Query Language Access Group specifications. The application programming interfaces enable Windows applications to access data in various back-end relational database servers (and xBase files), without the applications having to understand the differences between the various back-end data sources. Microsoft has also stated its intent to port ODBC to the Macintosh.
OEM : Original Equipment Manufacturer. Usually refers not to the manufacturer of a device, but to the system integrator that resells the devices as part of a system. When used as a verb, as in "Company B is going to OEM Company A's drive," this means that Company A will manufacture the drive and Company B will integrate it into a system.
OLE : Object Linking and Embedding. Microsoft-defined mechanism for program-to-program communication. OLE enables a user to create compound documents incorporating work from multiple applications.
Open Systems : A concept based on offering hardware and software and capabilities defined by standards - produced by standards committees as well as those supported or demanded by users (i.e., de facto standards, such as those developed by Unix International or the Open Software Foundation). Typically, an open system provides Unix as a basic operating system, although that is not a requirement; what is required is that the system provide standard interfaces. An open system is a compliant implementation of an evolving set of vendor-neutral specifications for interfaces, services, protocols and formats. It is designed to let users configure, operate and substitute an entire system, its applications and components with other equally compliant implementations, preferably available from different vendors.
Optical disk (Disque optique) : Disk whose reading and writing mechanisms use laser optics instead of magnetism. Their lifetime is probably long : more than 30 years for the support, but can we ensure to find decades later compatible reading mechanisms ? They can record relatively large quantities of data (500 MB in 1995), but their access time is slow.
Oracle : RDBMS world leader.
OS : Operating System. A computer's operating system mediates between user application programs and the processor and peripheral hardware environment. Under the control of the operating system, the computer recognises and obeys commands from the user and interprets application and network commands. The operating system also provides built-in routines that enable users to perform input/output operations without specifying the exact underlying hardware configuration of the computer.
OS/2 : Micro computer operating system developed by IBM. Although rather advanced, this system was never accepted by the users community.
OSI : Open Systems Interconnection. A standard approach to network design developed by the International Standards Organisation that introduces modularity by dividing the complex set of functions into more manageable, self-contained, functional slices.
Outsourcing : A contractual relationship with an external provider characterised by the transfer of assets (both physical and human), to include facilities management, network management, network management, PC services, and/or application development/maintenance.
Packet (Paquet) : An information block identified by a label at Layer 3 of the International Standards Organisation reference model for Open Systems Interconnection. It is a collection of bits that contain control information and data, and is the basic unit of transmission in a packet-switched network. Control information is carried in the packet, along with the data, to provide for such functions as addressing sequence, flow control and error control at each of several protocol levels. A packet can be of fixed or variable length, but generally has a specified maximum length.
PAD : Packet Assembler/Disassembler. An interface device that buffers data sent to and from character mode devices, and assembles and disassembles the packets needed for X.25 operations.
PABX : Private Branch Exchange. A telephone switch located on a customer's premises that primarily establishes voice-grade circuits (over tie lines to a telephone company central office) between individual users and the public-switched telephone network. The PABX also provides switching within the customer premises local area, and usually offers numerous enhanced features, including least-cost routing and call-details recording.
Parallel interface (Port parallˆle) : Interface allowing to exchange data in parallel mode : in this mode several bits are exchanged simultaneously, one on each data line. On a micro computer, used for example to connect a printer. To be opposed to "serial interface".
Parameter (Paramˆtre) : Variable affected to a command or a program. Characteristic of an element or a system , which can be adapted by the user.
PARC : Palo Alto Research Center. In this famous Xerox research center, most of the concepts used today in the micro computers were invented in the 70', such as graphical user interface, mouse, and Ethernet.
Passive matrix display (Affichage matriciel passif) : Display composed of a layer of LCD placed in a transparent network made of electrodes and red, green and blue filters. The current passes through the pixel rows and the display is back-lit in order to provide a better luminosity.
Password (Mot de passe) : Software security function preventing any access to the computer until this unique, predefined and secret password has been keyed in.
Pathway : Emulation software produced by the Wollongong company.
PC : Personal Computer.
PCB : Printed Circuit Board.
PCI : Peripheral Components Interconnect. Local bus specification defined by Intel.
PCL : Printer Control Language. A page-description language developed by Hewlett-Packard.
PCMCIA : Personal Computer Memory Card Industry Association. The organisation that promotes standards for small computer memory and input/output devices. PCMCIA cards come in three standard configuration: Type 1, 2, and 3, ranging in thickness from 2.2 mm to 10.5 mm, and offer a variety of functions including modems, Fax cards; local-area network connections and hard disks.
PDL : Page Description Language. Programming language, such as Postscript or PCL, allowing to indicate the printer how to edit the page.
Physical Layer (Couche Physique) : Within the Open Systems Interconnection model, the lowest level of network processing, below the link layer, that is concerned with the electrical, mechanical and handshaking procedures over the interface that connects a device to a transmission medium (e.g., RS-232-C)
Pixel : Picture Element (or PEL). The smallest resolvable dot in an image display.
Plug-and-Play : Facility allowing to plug a peripheral to the computer without previous powering it off. PCMCIA devices work this way. Beyond that, some operating systems allow the peripheral to be used without explicit configuration throughout a configuration utility. Windows95 aims to reach this goal (neither DOS nor Windows provide this facility).
PMF : Multifunctional workstation.
Port : The entrance or physical access point to a computer, multiplexer, device, or network where signals may be supplied, extracted, or observed.
POSIX : Portable Operating System Interface for Unix. A Unix-based standard developed by the Institute of Electrical and Electronics Engineers POSIX committee. In August 1988, the committee officially released the first instalment of the standard (1003.1), a core set of system calls. POSIX has been adopted as a Federal Information Processing Standard (FIPS), and is included in the Open Software Foundation's and X/Open's basic specifications.
POST : Power On Self-Test. Tests set executed automatically by the computer at power-on time. These tests count the memory space and check the different system components.
PostScript : PDL developed by the Adobe company for text and graphic data printing.
Protected mode : For Intel microprocessors, exploitation mode : the first MB can be addressed in real mode, the other ones (extended memory) in protected mode.
Protocol : Processing rules set. Generally applied to data transmission, where receiver and sender have to be configured in the same way in order to manage properly the transmission.
Power Point : MicrosoftÆs graphic presentation software.
Presentation Layer (Couche Presentation) : In the Open Systems Interconnection model, that layer of processing that provides services to the application layer, enabling it to interpret the data exchanged, as well as to structure data messages to be transmitted in a specific display and control format.
PTT : Postal Telegraph and Telephone. An agency in a European country, usually a government-run monopoly, that is responsible for all postal, telegraph and telephone services. It also has certain regulatory functions for telecommunications, such as providing specifications for modems and certifying that equipment may connect to the telephone network. In some countries, the PTT also provides its own line of equipment, such as modems. Now also called Telecommunications Administrations (TAs), these entities are undergoing varying amounts of structural change.
Queue (File d'attente) : Sequenced tasks set waiting for execution. In this waiting sequence, the first task is the first executed, so it is also called FiFo as First in/First out.
QWERTY : International keyboard. This acronym is composed of the six left characters of the upper character row, on an English or American-style keyboard
RAID : Redundant Array of Inexpensive Disks. A method of mirroring or striping data on clusters of low-end disk drives; data is copied onto multiple drives for faster throughput, error correction, fault tolerance and improved mean time between failures.
RAM : Random Access Memory. Part of storage containing the programs being executed. This technology generally requires regular refresh of the data, hundreds or thousands of times per second (in case of Dynamic RAM which is most frequent). Thus, the data are lost when the system is switched to power-off state.
RAM disk : Part of main storage used as a disk unit. Reading and writing being much faster in storage than on disk, RAM disk files speed up the program execution.
Real mode : For Intel microprocessors, production mode used to address the first storage MB. In real mode, the memory address used by the application is equal to the physical address in storage.
Refresh : Regular rewrite allowing to maintain displayed data on a screen or data in RAM storage.
Removable hard disk : Hard disk that can be removed from a laptop computer. This type of unit generates a special risk in terms of security.
Removable storage units : Magnetic tape, disk or cartridge on which are recorded data. Removable units are most frequently used to create safety copies of hard disk data.
Repeater (R‰p‰titeur) : A hardware device that adapts two wires or fibers to each other. It also amplifies the data before passing it to another medium. A repeater connects networks at OSI Layer 1.
Response Time (Temps de r‰ponse) : The time period between a terminal operator's completion of an inquiry and the receipt of a response. Response time includes the time taken to transmit the inquiry, process it by the computer, and transmit the response back to the terminal. Response time is frequently used as a measure of the performance of an interactive system.
Resolution : It defines the thinness of restitution of information provided by an output device such as a screen or a printer. It is usually measured in number of points. On screens, in 1995, the most frequent resolutions are 640 points per row and 480 points per column (called VGA), 800x600 (called SVGA) and 1024x768. On printers, it is measured in number of points per inch. On laser printers, in 1995, it is most frequently 300 or 600 points per inch. We can observe that resolution is much higher on printers than on screens.
RGB : Red Green Blue. Coloured components used for color display screens.
RISC : Reduced Instruction Set Computer. An architecture that shifts the analytical process of a computational task from the execution or run time to the preparation or compile time. By using less hardware or logic, the system can operate at higher speeds. A processor architecture that cuts down on the number and complexity of instructions, on the theory that each one can be accessed and executed faster, and that less semiconductor circuitry is required to process them. The result is that for any given semiconductor technology, a more powerful microprocessor can be produced with RISC than with CISC (complex instruction set computer) architectures. However, the compilers role becomes critical, and the effective throughput of the system will heavily depend on them.
RJ11 : Standard jacket for telephone line interface.
RJ45 : Standard interface type between computers and LANs, using UTP cables.
RNIS : "R‰seau Num‰rique € Int‰gration de Services". French name for ISDN. The commercially available service proposed by the national operator, France T‰l‰com, is named "Num‰ris".
ROM : Read-Only Memory. Storage unit which retains data even when the computer is powered off. This storage cannot be modified by the user.
Router (Routeur) : Performs a function similar to a local or remote bridge, but routing occurs at Layer 3 of the Open Systems Interconnection reference model.
Routine : Part of a program responsible for a complete function. A program composed of a number of distinct but linked routines is called "modular".
RPC : Remote Procedure Call. A mechanism that extends the notion of a local (i.e., contained in a single address space) procedure call to a distributed computing environment, enabling an application to be distributed among multiple systems in a way that is highly transparent to the application-level code. Examples of RPCs are Apollo's Network Computing System., Sun Microsystem's Open Network Computing, Sybase's Open Client/Open Server and the Open Software Foundation's Distributed Computing Environment RPC.
RS-232-C : A technical specification published by the Electronic Industries Association that establishes mechanical and electrical interface requirements between computers, terminals and communications lines.
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