Computer Glossary
10BaseT The most common network cabling method for Ethernet, which handles traffic at a speed of 10Mbps. 10BaseT uses a pair of unshielded twisted conductors to connect between a network interface card (NIC) and an Ethernet hub. 10Base2 (thin Ethernet, or thinnet) uses coaxial cable connections between computers and doesn't require a hub. 100BaseT is a newer medium that supports up to 100Mbps. See Ethernet, hub, and NIC.
accelerator key A key combination that provides access to a menu choice, macro, or other function of the application instead of selection with the mouse, usually combining Alt+key. Sometimes called a shortcut key, but shortcut keys usually consist of Ctrl+key combinations.
Access Control List (ACL) Part of Windows NT's security description that controls access to a Windows NT object, such as a file. The owner of an object can change access control entries in the list to grant or revoke permissions (access rights) for the object.
access token A Windows NT object that identifies a logged-on (authenticated) user. The access token contains the user's security ID (SID), the groups to which the user belongs, and other security information. See SID.
activation An ActiveX and OLE term meaning to place an object in a running state, which includes binding the object, or to invoke a method of the object. See also binding.
active In Windows, the currently running application or the window to which user input is directed; the window with the focus. See also focus.
ActiveX A family of Microsoft object technologies, formerly called OLE, based on the Common Object Model (COM), serving as one of the foundation of Microsoft's Internet products. See COM and DCOM.
ActiveX control An insertable COM object (component) that usually provides user interface components and can fire events. ActiveX controls are lightweight versions of OLE Controls (.OCXs)
address The numerical value, usually in hexadecimal format, of a particular location in your computer's RAM.
address space Memory allocated to an application by the operating system. See virtual address space.
aggregate object An ActiveX and OLE term that refers to an object class that contains one or more member objects of another class.
alert In Windows NT, a message sent between two simultaneously executing threads that results in an asynchronous procedure call (APC) executed by the receiving thread. Also means a message indicating abnormal operation of a Windows NT process.
ANSI An abbreviation for the American National Standards Institute. In the Windows context, ANSI refers to the ANSI character set. Windows 95 and Windows NT include both ANSI (suffix A) and Unicode (suffix W) versions of Windows API functions. See ASCII and Unicode.
API An abbreviation for application program interface. Generically, a method by which a program can obtain access to or modify the operating system. See also DLL.
applet A Windows application that's supplied as a component of another Windows application, rather than as a retail product. The Notepad and Wordpad applications supplied with Windows NT are examples of applets.
application The software product that results from the creation of a program, often used as a synonym for the programming (source) code that creates it. Applications are distinguished by the environment for which they're designed (for example, Windows, DOS, Macintosh, UNIX) and their purpose. Windows applications carry the executable file extension, .EXE.
application Close button The small, square button with an [ts] caption at the extreme right of the title bar of an application running in Windows NT and Windows 95. Clicking the application Close button closes the running application.
application Control-menu box The small, square button with a miniature application icon at the extreme left of the title bar of an application window. Clicking the application Control-menu box displays the application Control menu. Double-clicking the application Control-menu box closes the application.
ASCII Abbreviation for American Standard Code for Information Interchange. A set of standard numerical values for printable, control, and special characters used by PCs and most other computers. Other commonly used codes for character sets are ANSI (used by Windows 3.1+), Unicode (used by Windows 95 and Windows NT), and EBCDIC (Extended Binary-Coded Decimal Interchange Code, used by IBM for mainframe computers). See Unicode.
asymmetric multiprocessing A multiprocessing technique in which individual processors are dedicated to particular tasks, such as running the operating system or performing user requests. See SMP.
asynchronous A process that can occur at any time, regardless of the status of the operating system or applications that are running. An example is Windows NT's asynchronous procedure call (APC).
asynchronous I/O Input/output operations in which an application issues an I/O request to a device, and then continues operation while the device transfers data. Asynchronous I/O greatly speeds fixed-disk file operations. See synchronous I/O.
auditing Windows NT's capability to record and report security-related events, such as accessing, creating, or deleting files.
authentication The process of verifying (validating) a user's logon ID and password, usually used to provide access to network resources.
Automation An ActiveX (OLE) term that refers to a means of manipulating another application's objects by the use of a programming language, most commonly Visual Basic for Applications (VBA).
Automation controller An ActiveX-compliant Windows application with an application programming (macro) language, such as VBA, that can reference and manipulate objects exposed by ActiveX components and Automation servers. Automation controller replaces the term OLE Automation client.
Automation server Technically, any OLE 2-compliant Windows application that supports OLE Automation operations by exposing a set of objects for manipulation by OLE Automation client applications. In ActiveX terminology, ActiveX components are Automation servers.
autoplay A feature of Windows 95's and Windows NT 4.0's CD-ROM file system (CDFS) that automatically executes a program on the CD-ROM when inserted into the CD-ROM drive.
back up To create a file (backup file) that duplicates data stored in one or more files on a client or server computer.
background In multitasking computer operations, a running application or process that isn't visible on-screen and isn't receiving user-generated input.
batch A group of statements processed as an entity. Execution of DOS batch files (such as AUTOEXEC.BAT) and SQL statements are examples of a batch process.
BDC An abbreviation for Backup Domain Controller, a Windows NT server that provides an alternative source of authentication for network users. Account and group information from a Primary Domain Controller (PDC) is replicated periodically to each BDC in the domain. See PDC.
binary file A file whose content doesn't consist of lines of text. Executable (.EXE), dynamic link library (.DLL), and most database files are stored in binary format.
binding In ActiveX and OLE, a term for the act of connecting a component (server object) to a controller (OLE client).
bit The smallest piece of information processed by a computer. A bit, derived from the contraction of BInary digiT (or Binary digIT) has two states-on (1) or off (0). Eight bits make up a byte; 16 bits combined is called a word.
bitmap The representation of a screen or printed image, usually graphic, as a series of bytes.
bitwise A process that evaluates each bit of a combination, such as a byte or word, rather than process the combination as a single element. Logical operations and masks use bitwise procedures.
blitting The process of using the BitBlt() function of Windows' Gdi32.exe to modify a bitmap using bit block transfer.
Boolean A type of arithmetic in which all digits are bits-that is, the numbers may have only two states: on (true or 1) or off (false or 0). Widely used in set theory and computer programming, Boolean, named after mathematician George Boole, also is used to describe a data type that may have only two states: true or false.
break To cause an interruption in program operation. Ctrl+C is the standard DOS break-key combination but seldom halts operation of a Windows application. Esc is more commonly used in Windows to cause an operation to terminate before completion.
BRI An abbreviation for Basic Rate Interface, the standard ISDN service for business and residential Internet connections. BRI has two 56kbps B (bearer) channels and one 16kbps D (data) channel, providing a maximum bandwidth of 112kbps. See ISDN and PRI.
bridge An active network device used to divide a network into mutually isolated segments while maintaining the whole as a single network. Bridges operate at the data-link layer of the OSI Reference Model. See OSI.
buffer An area in memory of a designated size (number of bytes or characters) reserved, typically, to hold a portion of a file or the value of a variable.
business rules A set of rules for entering data in a database that are specific to an enterprise's methods of conducting its operations. Business rules are in addition to rules for maintaining the domain and referential integrity of tables in a database. Business rules most commonly are implemented in a three-tier client/server database environment. See three-tier.
cache A block of memory reserved for temporary storage. Caches usually store data from disk files in memory to make access to the data faster. By default, Windows NT caches all disk read and write operations.
cache manager A component of Windows NT's I/O system that uses the virtual memory (VM) manager to create temporary storage in the paging file to speed disk I/O operations. See VM.
caret The term used by Windows to indicate the cursor used when editing a text field, usually shaped as an I-beam. The caret, also called the insertion point, can be positioned independently of the mouse pointer.
CDFS The 32-bit CD-ROM file system shared by Windows NT and Windows 95.
channel A dedicated communication connection between a transmitting and receiving device. Channel is also used to identify an I/O port in mini- and mainframe computers.
CISC Complex instruction set computer, a microprocessor whose internal instructions often involve many individual execution steps and thus many clock cycles. The Intel 80x86 processors are the most common CISC devices. See RISC.
class identifier See CLSID.
client The device or application that receives data from or manipulates a server device or application. The data may be in the form of a file received from a network file server, or an object created from an ActiveX component or OLE server. See Automation controller.
CLSID An identification tag that's associated with an ActiveX or OLE 2.0 object created by a specific component or server. CLSID values appear in the Registry and must be unique for each type of object that the server can create. See Registry.
clustering A server architecture that emulates multiprocessing by interconnecting two or more individual computers in order to share the application processing load. Microsoft's future clustering technology for Windows NT now carries the code name Wolfpack. A number of third parties offer proprietary clustering hardware and software for Windows NT Server 4.0.
collection A group of objects of the same class that are contained within another object. Collections are named as the plural of their object class.
COM An acronym for Component Object Model, the name of Microsoft's design strategy to implement OLE 2+ and ActiveX. Distributed COM (DCOM) allows networked and cross-platform implementation of ActiveX and OLE 2+ operations and Automation. See Automation and DCOM.
common dialogs A standardized set of dialog boxes common to Windows 95 and Windows NT 4.0. Common dialogs include File Open, File Save, Print, and Printer Setup.
Component Object Model See COM.
compound document A document that contains OLE objects created by an application other than the application that originally created or is managing the document.
concurrency The condition when more than one user has access to a specific set of records or files at the same time. Concurrency is also used to describe a database management system's capability to handle simultaneous queries against a single set of tables.
concurrent application An application capable of simultaneous execution in multiple address spaces. Windows NT uses threads of execution to support concurrent applications.
console A character-based interface to an operating system. Windows NT uses the Command Prompt tool as the console.
container An object or application that can create or manipulate compound documents. For example, Internet Explorer is a container for ActiveX objects.
context switching The process of saving an executing thread or process and transferring control to another thread or process. Windows NT 4.0's context switching, one of the major bottlenecks in COM operations, is substantially faster than in Window NT 3.x.
control A synonym for a visible dialog or window object, such as include labels, text boxes, lists, combo lists, option buttons, and command buttons.
Control-menu box See application Control-menu box and document Control-menu box.
control object In Windows NT, objects that control system tasks, such as asynchronous and deferred procedure calls.
custom control A control object not native to the application, such as an ActiveX control or a Visual Basic Extension control (VBX).
data definition The process of describing databases and database objects such as tables, indexes, views, procedures, rules, default values, triggers, and other characteristics.
data dictionary The result of the data definition process. Also used to describe a set of database system tables that contain the data definitions of database objects.
data integrity The maintenance of rules that prevent inadvertent or intentional modifications to the content of a database that would be deleterious to its accuracy or reliability. See domain integrity and referential integrity.
database A set of related data tables and other database objects, such as a data dictionary, which are organized as a group.
database administrator The individual responsible for the administrative functions of client-server databases. The database administrator (DBA) has privileges (permissions) for all commands that may be executed by the RDBMS and is ordinarily responsible for maintaining system security, including access by users to the RDBMS itself and performing backup and restoration functions.
database device A file in which databases and related information, such as transaction logs, are stored. Database devices usually have physical names, such as a file name (Master.dat), and a logical name, such as master.
database owner The user who originally created a database. The database owner has control over all the objects in the database but may delegate control to other users. The database owner is identified by the prefix dbo in SQL Server.
DCOM An acronym for Distributed Common Object Model that allows communication and manipulation of objects over a network connection. Windows NT 4.0 is the first Microsoft operating system to support DCOM (formerly called NetworkOLE). See COM.
DDE An abbreviation for dynamic data exchange, an early Interprocess Communication (IPC) method used by Windows and OS/2 to transfer data between different applications. Automation (formerly OLE Automation) provides a more robust IPC method.
deadlock A condition that occurs when two users with a lock on one data item attempt to lock the other's data item. Most RDBMSs detect this condition, prevent its occurrence, and advise both users of the deadlock situation.
default A value assigned or an option chosen when no value is specified by the user or assigned by a program statement.
demand lock Precludes more shared locks from being set on a data resource. Successive requests for shared locks must wait for the demand lock to be cleared.
device A computer system component that can send or receive data, such as a keyboard, display, printer, disk drive, or modem. Windows NT uses device drivers to create device objects that connect applications to devices.
DHCP Abbreviation for Dynamic Host Configuration Protocol, an Internet standard protocol that allows IP addresses to be pooled and assigned as needed to clients. Windows NT 4.0 includes DHCP Manager, a graphical DHCP configuration tool. See IP and IP address.
dialog A popup modal child window, also called a dialog box, that requests information from the user. Dialogs include message boxes, input boxes, and user-defined dialogs for activities such as choosing files to open.
DIB An acronym for device-independent bitmap, a Windows-specific bitmap format designed to display graphic information. DIB files take the extension .DIB and use a format similar to the .BMP format.
directory list An element of a file-selection dialog that selectively lists the subfolders of the designated folder of a specified logical drive.
dispatcher A Windows NT operating system component that schedules the execution of application threads.
distributed database A database, usually of the client/server type, that's located on more than one database server, often at widely separated locations. Synchronization of data contained in distributed databases is most commonly accomplished by the two-phase commit or replication methods. See replication and two-phase commit.
disk mirroring Creating on two or more physical disk drives exact duplicates of a disk volume to make files accessible in case of failure of one drive of the mirror set. See RAID.
disk striping Distributing the data for a single logical disk volume across two or more physical disk drives. Simple disk striping (RAID 0) provides faster I/O operation. Disk striping with parity (RAID 5) provides faster I/O and protection from failure of a physical disk in a stripe set. See RAID.
DLC An abbreviation for Data Link Control, a Windows NT protocol used to communicate with mainframes and networked laser printers.
DLL An abbreviation for dynamic link library, a file containing a collection of Windows functions designed to perform a specific class of operations. Most DLLs carry the .DLL extension, but some Windows DLLs, such as Gdi32.exe, use the .EXE extension. Functions within DLLs are called (invoked) by applications as necessary to perform the desired operation.
document A programming object containing information that originates with the user of the application, rather than created by the application itself. The data for documents usually is stored in disk files.
document Control-menu box The small, square button at the upper left of the menu bar of an application that uses the multiple document interface (MDI). Clicking the document Control-menu box displays the document Control menu. Double-clicking the document Control-menu box closes the document (but not the application).
domain In Windows NT, a group of workstations and servers that share a common Security Accounts Manager (SAM) database and allow a user to log on to any resource in the domain with a single user ID and password.
domain integrity The process of assuring that values added to fields of a table comply with a set of rules for reasonableness and other constraints. See business rules and three-tier.
dynamic data exchange See DDE.
dynamic link library See DLL.
environment A combination of the computer hardware, operating system, and user interface. A complete statement of an environment follows: a Pentium PCI-bus computer with 64M of RAM, a Wide and Fast SCSI host adapter, SVGA display adapter, sound card, and two-button mouse, using the Windows NT Server 4.0 operating system.
environmental subsystem In Windows NT, the four sets of APIs that support Win32, MS-DOS, POSIX, and OS/2 applications.
Ethernet A networking medium that was developed at the Xerox Palo Alto Research Center (PARC) in the 1970s; was improved by Xerox, Intel, and Digital; and is now the most popular cabling method for LANs. The IEEE 802.3 specification for Ethernet is the most common implementation.
event Most commonly, the occurrence of an action taken by the user, such as right-clicking the mouse, that's recognized by the operating system and passed to the foreground application. Windows NT and its server applications generate events, such as problem reports, without user intervention.
event-driven The property of an operating system or environment, such as Windows, that implies the existence of an idle loop. When an event occurs, the idle loop is exited and event-handler code, specific to the event, is executed. After the event handler has completed its operation, execution returns to the idle loop, awaiting the next event.
exception An error, such as division by zero, detected by hardware or by the operating system. Fatal exceptions halt execution of an application and, in a few circumstances, kill the operating system.
executable Code, usually in the form of a disk file, that can be run by the operating system in use to perform a particular set of functions. Executable files in Windows carry the extension .EXE and may obtain assistance from dynamic link libraries (DLLs) in performing their tasks.
executive In Windows NT, the components of the operating system that run in the kernel (ring 0) and handle interprocess communication, interrupt requests, and object security. Graphics operations have been moved from user mode to kernel mode in Windows NT 4.0 to speed performance. See kernel mode and user mode.
failover A fault-tolerant clustering architecture in which two servers share a common set of fault-tolerant fixed disk drives. In the event of failure of one of the servers, the other transparently assumes all server processing operations. See clustering and fault tolerance.
FAT An acronym for file allocation table, the disk file system used by MS-DOS, Windows 95, and (optionally) Windows NT. Windows NT is compatible with the 16-bit FAT system, but not the optional 32-bit FAT (FAT32) for Windows 95 that Microsoft announced in mid-1996. See HPFS and NTFS.
fault tolerance A computer system's capability to maintain operability, despite failure of a major hardware component such as a power supply, microprocessor, or fixed-disk drive. Fault tolerance requires redundant hardware and modifications to the operating system. Windows NT Server includes fault tolerance for a failed disk drive by disk mirroring (RAID 1) or disk striping with parity (RAID 5). Clustering provides fault tolerance for individual computers. See clustering and RAID.
fiber A lightweight thread, introduced in Windows NT 4.0, that makes it easier for developers to optimize scheduling within multithreaded applications. See thread.
focus A Windows term indicating the currently selected application, or one of its windows, to which all user-generated input (keyboard and mouse operations) is directed. The title bar of a window with the focus is colored blue for the default Windows color scheme.
foreground In multitasking operations, the application or procedure that's visible and to which user-generated input is directed. In Windows, the application that has the focus is in the foreground.
front end When used with database management systems, an application, a window, or a set of windows by which the user may access and view database records, as well as add to or edit them.
function A subprogram called from within an expression in which a value is computed and returned to the program that called it through its name. Functions are classified as internal to the application language when their names are keywords.
gateway A hardware device or software program used to translate between incompatible protocols. A gateway can function at any one layer of the OSI Reference Model or at several layers simultaneously. For example, a gateway is used to translate between mail systems, such as SNMP and MHS. (Internet terminology uses the term gateway in place of router.)
global Pertaining to an entire entity, such as a Windows NT domain or a collection of trusted/trusting domains. Windows NT distinguishes global groups from local groups; local groups have permissions only for objects on the server in which the local group exists.
group A collection of network or database users with common permissions for particular objects, such as shared files or database tables. See also permissions.
HAL An acronym for hardware abstraction layer, a Windows NT DLL that links specific computer hardware implementations with the Windows NT kernel. Windows NT 4.0 includes HALs for 80x86, Alpha, MIPS, and PowerPC hardware platforms.
handle An unsigned long (32-bit) integer assigned by Windows NT or Windows 95 to uniquely identify an instance (occurrence) of an object, such as a file or a window.
host Any computer on a network using the Internet Protocol (IP). See IP and IP address.
HPFS An abbreviation for the High-Performance File System used by OS/2 and (optionally) Windows NT 3.x. Windows NT 4.0 doesn't support HPFS but can connect via a network to files on HPFS volumes of Windows NT 3.x PCs.
HTML An abbreviation for HyperText Markup Language, a variant of SGML (Standardized General Markup Language), a page-description language for creating files that can be formatted and displayed by World Wide Web browsers.
hub A concentrator that joins multiple clients by means of a single link to the rest of the LAN. A hub has several ports to which clients are connected directly, and one or more ports that can be used to connect the hub to the backbone or to other active network components. A hub functions as a multiport repeater; signals received on any port are immediately retransmitted to all other ports of the hub. Hubs function at the physical layer of the OSI Reference Model.
icon A 32-by-32-pixel graphic image used to identify the application in the Explorer window and in other locations in the application chosen by the programmer (such as the Help About dialog). Windows NT 4.0 and Windows 95 also use 16-by-16-pixel small icons to identify the application in the title bar and elsewhere where small icons are specified.
idle In Windows, the condition or state in which both Windows and the application have processed all pending messages in the queue from user- or hardware-initiated events and is waiting for the next event to occur. In Windows NT multiprocessing, one idle thread exists for each processor.
impersonation In Windows NT, the capability of a thread in one process to assume the security identity of another process. Impersonation is employed by a named pipe to acquire and use the security ID of the service requester.
index For arrays and collections, the position of the particular element with respect to others, usually beginning with 0 (arrays) or 1 (collections) as the first element. When used with database files or tables, index refers to a lookup table, usually in the form of a file or component of a file, that relates the value of a field in the indexed file to its record or page number and location in the page (if pages are used).
initialize In programming, setting all variables to their default values and resetting the point of execution to the first executable line of code.
in-place activation The capability to activate an object (launch another application) and have the container application take on the capabilities of the other application. The primary feature of in-place activation (also called in-situ activation) is that the other application's menu choices merge with or replace the container application's menu choices in the active window.
in-process A term applied to Automation servers, also called Automation DLLs, that operate within the same process space (memory allocation) of the Automation controller manipulating the server. In-process servers commonly are called InProc servers. See out-of-process.
installable file system In Windows NT, the capability to load a file system (such as NTFS, CDFS, FAT, or HPFS) dynamically, depending on the format of the file to be opened.
instance A term used by Windows to describe the temporal existence of a loaded application or one or more of its windows.
instantiate The process of creating an instance of an object in memory.
interface A noun describing a connection between two dissimilar devices or COM objects, such as Automation clients and servers. A common phrase is user interface, meaning the "connection" between the display-keyboard combination and the user. Use of interface as a verb is jargon.
interrupt An asynchronous message, usually issued by an I/O device, requesting the service of an operating system's or device driver's interrupt handler.
intranet A private network that uses Internet protocols and common Internet applications (such as Web browsers) to emulate the public Internet. Intranets on LANs and high-speed WANs provide increased privacy and improved performance compared with today's Internet.
invocation path The route through which an object or routine is invoked. If the routine is deeply nested, the path may be quite circuitous.
invoke To cause execution of a block of code, particularly a procedure or subprocedure. Invoke also is used to indicate application of a method to an object.
I/O manager A component of the Windows NT executive that handles all input/output (I/O) requests.
IP An abbreviation for Internet Protocol, the basic network transmission protocol of the Internet.
IP address The 32-bit hexadecimal address of a host, gateway, or router on an IP network. For convenience, IP addresses are specified as the decimal value of the four address bytes, separated by periods, as in 124.33.15.1. Addresses are classified as types A, B, and C, depending on the subnet mask applied. See subnet mask.
IPX/SPX Abbreviation for Internetwork Packet Exchange/Sequenced Packet Exchange, the transport protocol of Novell NetWare, supported by Windows NT's NWLink service. See NWLink.
ISDN An abbreviation for Integrated Services Digital Network, a switched telephone service that provides mid-band digital communication capabilities used for Internet connections and for remote access to LANs, as well as voice communication. Windows NT 4.0 has built-in support for ISDN modems, more properly called network terminators. See BRI and PRI.
item The name given to one of the elements contained in a list box or drop-down list, or the list component of a combo box.
kernel mode The mode in which the Windows NT system runs, providing the operating system with access to system memory and other hardware devices.
key A collection of one or more Registry values (properties) that relate to a single object.
key or key field In relational database tables, a field that identifies a record by its value. Tables are usually indexed on key fields. For a field to be a key field, each data item in the field must possess a unique value.
LAN An acronym for local area network. A LAN is a system comprising multiple computers that are physically interconnected through network adapter cards and cabling.
launch To start a Windows application.
library A collection of functions, compiled as a group and accessible to applications by calling the function name, together with any required arguments. DLLs are one type of library; those used by compilers to provide built-in functions are another type.
linked object A source document in a compound document that's included by reference to a file that contains the object's data, rather than by embedding the source document in the compound document.
livelock A request for an exclusive lock on a file or data item that's repeatedly denied because of shared locks imposed by other users.
local area network See LAN.
locale The environment for an operating system or application, usually based on a specific language or a dialect of a language. Windows NT uses the National Language Support (NLS) API to provide localization.
lock In databases, a restriction of access to a table, portion of a table, or data item imposed to maintain data integrity of a database. Locks may be shared (more than one user can access the locked element or elements) or exclusive (the user with the exclusive lock prevents other users from creating simultaneous shared or exclusive locks on the element or elements).
logical The manifestation of physical devices in software, including operating systems. For example, a logical disk drive may consist of a part of the space on a single disk drive or, using Windows NT's capability of spanning drives, space on multiple disk drives.
logon The process by which Windows NT detects an attempt of a user to gain access to the operating system. Successful completion of the logon process authenticates the user.
LRPC An abbreviation for lightweight remote procedure call used for communication between ActiveX controllers (OLE clients) and ActiveX components (OLE servers) residing on a single computer. See remote procedure call (RPC).
MAC An acronym for Media Access Control, the globally unique hardware address of an Ethernet network interface card.
machine language Program code in the form of instructions that have meaning to and can be acted on by the computer hardware and operating system used. Object files compiled from source code are in machine language, as are executable files that consist of object files linked with library files. Windows NT is individually compiled for the machine language of each platform that uses a different processor.
map To translate a physical memory address to a virtual memory (VM) address, or vice versa. See VM.
MAPI Acronym for the Windows Messaging API originally created by Microsoft for use with Microsoft Mail, which implements Simple MAPI. Microsoft Exchange Client and Server implements MAPI 1.0 (also called Extended MAPI).
metafile A type of graphics file, used by Windows and other applications, that stores the objects displayed in the form of mathematical descriptions of lines and surfaces. Windows NT 4.0 supports enhanced metafiles (EMF) for improved printing performance.
method One of the characteristics of an object and a classification of keywords in VBA. Methods are the procedures that apply to an object. Methods that are applicable to a class of objects are inherited by other objects of the same class and may be modified to suit the requirements of the object.
MIB An acronym for Management Information Base, a set of attributes for active network components, including servers, used by SNMP. Windows NT provides MIBs for server shares, sessions, and users, plus DHCP and WINS data. See SNMP.
mini-server An applet with OLE server capabilities that you can't run as a stand-alone application. Microsoft Graph is an example of a mini-server (despite the size of its executable file).
mirroring See disk mirroring.
MISF An abbreviation for Microsoft Internet Security Framework, a set of high-level security services that rely on CryptoAPI 2.0 functions to provide certificate- and password-based authentication. MISF also incorporates secure channel communication using SSL (Secure Sockets Layer) 2.0 and 3.0, plus PCT (Personal Communications Technology), SET (Secure Electronic Transactions) for credit-card purchases, and the Microsoft Certificate Server for issuing authentication certificates.
modal A dialog that must be closed before the user can take further action.
modeless A window or dialog that the user may close or minimize without taking any other action-the opposite of modal.
multiprocessing The capability of a computer with two or more CPUs to allocate tasks (threads) to a specific CPU. See SMP.
multitasking The capability of a computer with a single CPU to simulate the processing of more than one task at a time. Multitasking is effective when one (or more) of the applications spends most of its time in an idle state, waiting for a user-initiated event such as a keystroke or mouse click.
multithreaded An application that contains more than one thread of execution; a task or set of tasks that executes semi-independently of other task(s).
multiuser Concurrent use of a single computer by more than one user, usually through the use of remote terminals. UNIX is inherently a multiuser operating system. Multiuser is often used as a term to describe an application that allows multiple users to view and update a single shared file, such as a Microsoft Access .MDB file.
named pipes A method of interprocess communication, originally developed for OS/2, that provides a secure channel for network communication.
NBF An abbreviation for NetBEUI Frame, the transport packet structure used by NetBEUI.
NCBS An abbreviation for Network Control Block Session, a NetBIOS connection using the NetBEUI Frame protocol. Clients issue an NCB CALL and the destination server returns an NCB LISTEN to establish the session.
NDIS An acronym for Microsoft's Network Driver Interface Specification for writing device drivers for network interface cards (NICs) that work with Windows 3.x, Windows 95, and Windows NT.
NetBEUI An acronym for NetBIOS Extended User Interface, the transport protocol of Microsoft Networking. NetBEUI isn't a routable network, so its popularity is declining in comparison with TCP/IP.
NetBIOS An acronym for Network Basic Input/Output System, the original network API for MS-DOS and the foundation for NetBEUI.
NFS An abbreviation for Network File System, a file format and set of drivers created by Sun Microsystems Incorporated that allows DOS/Windows and UNIX applications to share files on disk drives running under UNIX. NFS relies on remote procedure calls (RPCs) for communication between clients and servers.
NIC An acronym for network interface card, a plug-in adapter card that provides the physical connection to the network. The most common NICs support 10BaseT network media; 100BaseT NICs, which are 10 times faster, are gaining acceptance in Windows NT networks.
NT An abbreviation for New Technology used by Windows NT. Windows NT is a registered trademark of Microsoft Corporation, so the full name of the operating system, Windows NT, is used in this book.
NTFS An abbreviation for New Technology File System, Windows NT's replacement for the DOS FAT (File Allocation Table) and OS/2's HPFS (High-Performance File System). NTFS offers many advantages over other file systems, including improved security and the ability to reconstruct files in the event of hardware failures. Windows 3.1+ and Windows 95 can access files stored on NTFS volumes via a network connection but can't open NTFS files directly.
NWLink Microsoft's implementation of the Novell NetWare IPX/SPX protocol for Windows NT Server and Workstation. See IPX/SPX.
object In programming, an element that combines data (properties) and behavior (methods) in a single container of code. Objects inherit their properties and methods from the classes above them in the hierarchy and can modify the properties and methods to suit their own purposes.
object code Code in machine-readable form that can be executed by your computer's CPU and operating system, usually linked with libraries to create an executable file.
object library A file with the extension .OLB that contains information on the objects, properties, and methods exposed by an .EXE or .DLL file of the same file name that supports Automation.
object manager A Windows NT executive component that manages operating system resources. In Windows NT, all system resources are objects.
object permissions Permissions granted by the network administrator for users to access shared Windows NT objects. Object permissions also may be granted to users through group membership.
ODBC An abbreviation for the Microsoft Open Database Connectivity API, a set of functions that provide access to client-server RDBMSs, desktop database files, text files, and Excel worksheet files through ODBC drivers. Windows NT 4.0 and Windows 95 use 32-bit ODBC 2.5. ODBC most commonly is used to connect to client/server databases, such as Microsoft SQL Server.
OLE Automation See Automation.
OLE Control See ActiveX control.
OLE DLL A synonym for an in-process Automation server implemented as a Windows DLL. See in-process.
OpenDoc A standard proposed by Apple Computer, Borland International, Lotus Development, Novell, and other Microsoft competitors to supplant or replace COM, DCOM, and OLE.
option button A synonym for radio button, the original terminology in the CUA specification. Option buttons are circular control objects whose center is filled when selected. If grouped, only one option button of a group may be selected.
OSI Abbreviation for Open System Interconnection, the model for standard levels of networking functions and the services performed at each level. The seven-level OSI standard is defined by the International Standards Organization (ISO).
out-of-process An (OLE) Automation server in the form of an executable (.EXE) file that operates in its own process space (memory allocation) and uses LRPCs (lightweight remote procedure calls) to communicate with the Automation client. The term OutOfProc often is used as shorthand for out-of-process.
page A block of contiguous virtual memory (VM) addresses that Windows NT moves between physical RAM and a disk (paging) file as needed to support network operations and applications. Paging is used when physical RAM can't store the required data. See VM.
page fault An event that occurs when a thread refers to an invalid (out-of-date) VM page. The VM manager must refresh the page from the page file. See VM.
paged pool System memory that can be paged to Windows NT's Pagefile.sys paging file. The non-paged pool (approximately 4M for Windows NT 4.0) must reside in RAM and can't be paged to disk.
parameter The equivalent of an argument but associated with the procedure that receives the value of an argument from the calling function. The terms parameter and argument, however, are often used interchangeably.
PDC An abbreviation for Primary Domain Controller, the Windows NT server in a domain that's responsible for maintaining user and group accounts for a domain. Primary and Backup Domain Controllers authenticate domain users during the logon process. See BDC and logon.
permissions Authority given by the system administrator, database administrator, or database owner to perform operations over a network or on data objects in a database.
persistent object An object that's stored in the form of a file or an element of a file, rather than only in memory.
port A connection to an external hardware device, such as a modem (serial port) or a printer (printer). In Windows NT, a communications channel object for local procedure calls.
PPP An abbreviation for Point-to-Point Protocol, the most common Internet protocol for connection to TCP/IP networks via conventional and ISDN modems. See SLIP.
PPTP An abbreviation for Point-to-Point Tunneling Protocol, a Microsoft-sponsored protocol, included with Windows NT 4.0, that uses encryption to assure privacy of communication over the Internet. See VPN.
preemptive multitasking The multitasking process used by Windows NT and Windows 95 in which the operating system assures that all active threads have the opportunity to execute. Preemptive multitasking prevents a single thread from monopolizing a processor.
PRI An abbreviation for Primary Rate Interface, an ISDN service for high-speed communication. PRI has 23 64kbps B (bearer) channels and one 64kbps D (data) channel, which may be used as independent channels or bonded to provide bandwidths higher than 64kbps. See ISDN and BRI.
primary key The column or columns of a table whose individual or combined values (in the case of a composite primary key) uniquely identify a row in a table.
property One of the two principal characteristics of objects (the other is methods). Properties define the manifestation of the object-for example, its appearance. Properties may be defined for an object or for the class of objects to which the particular object belongs, in which case they are said to be inherited.
property sheet A dialog used to set the value(s) of properties of an object, such as an ActiveX control or an operating system component. As an example, Control Panel's Network tool is a property sheet. The tabbed elements of a property sheet are called property pages.
protected subsystem A process that operates in a block of virtual memory that's not shared with other processes. Windows NT's protected subsystems prevent an errant process from killing the entire operating system.
protocol A description of the method by which networked computers communicate. Windows NT allows the simultaneous use of multiple network protocols, including TCP/IP, NetBEUI, and IPX/SPX.
protocol stack Network protocol software that implements a specific protocol, such as TCP/IP.
query A request to retrieve data from a database with the SQL SELECT instruction or to manipulate data stored in tables.
RAID An acronym for redundant array of inexpensive disks, a method of connecting multiple disk drives to a single controller card to achieve faster data throughput, data storage redundancy for fault tolerance, or both. See disk mirroring, disk striping, and fault tolerance.
raising exceptions A process by which the operating system transfers control to a block of software (exception handler) when an error or unexpected condition occurs. Windows NT's exception handler adds items to the event log.
RDBMS An abbreviation for relational database management system. An RDBMS is an application that can create, organize, and edit databases; display data through user-selected views; and, in some cases, print formatted reports.
record In database applications, a single element of a relational database table that contains each field defined for the table. A record is the logical equivalent of the row of a spreadsheet.
redirector Software that intercepts requests for remotely provided services, such as files in server shares, and sends the request to the appropriate computer on the network.
referential integrity Rules governing the relationships between primary keys and foreign keys of tables within a relational database that determine data consistency. Referential integrity requires that the value of every foreign key in every table be matched by the value of a primary key in another table.
Registry A database that contains information required for the operation of Windows NT and Windows 95, plus applications installed under Windows NT and Windows 95. The Windows Registry takes the place of Windows 3.1+'s REG.DAT, WIN.INI, and SYSTEM.INI files, plus PROFILE.INI files installed by Windows 3.1 applications. The Registry also includes user information, such as user IDs, encrypted passwords, and permissions. Windows NT and Windows 95 include RegEdit.exe for editing the Registry. The Windows NT and Windows 95 Registries differ in structure, and thus are incompatible.
relational database See RDBMS.
Remote Automation Object An out-of-process (OLE) Automation server, usually called an RAO, that resides on a server and is accessible to RAO-compliant applications that connect to the server. RAOs comprise the middle tier of three-tier client/server database applications. See business rules and three-tier.
remote procedure call (RPC) An interprocess communication method that allows an application to run specific parts of the application on more than one computer in a distributed computing environment. Windows NT 4.0's DCOM uses RPCs for network communication between COM objects.
replication The process of duplicating server shares and database objects (usually tables) in more than one location, including a method of periodically rationalizing (synchronizing) updates to the objects. Database replication is an alternative to the two-phase commit process. Microsoft SQL Server 6+ supports replication of databases across multiple Windows NT servers. Updating Windows NT Backup Domain Controllers (BDCs) from a Primary Domain Controller (PDC) occurs by replication of the Security Accounts Manger (SAM) database.
RISC An acronym for Reduced Instruction Set Computer, a processor that uses a simplified set of internal operating instructions to speed execution. RISC processors supported by Windows NT 4.0 are Alpha, MIPS, and PowerPC. See CISC.
rollback A term used in transaction processing that cancels a proposed transaction which modifies one or more tables and undoes changes, if any, made by the transaction before a COMMIT or COMMIT TRANSACTION SQL statement.
router An active network component that connects one network to another network. Routers operate at the network layer of the OSI and work with packets that include logical addressing information.
routine A synonym for procedure.
SAM An acronym for Security Accounts Manager, a Windows NT subsystem that maintains a database of user account names and passwords for authentication.
scalable The property of a multiprocessing computer that defines the extent to which addition of more processors increases aggregate computing capability. Windows NT Server 4.0 is generally considered to be scalable to eight Intel processors.
server A computer on a LAN that provides services or resources to client computers by sharing its resources. Servers may be dedicated, in which case they share their resources but don't use them themselves, except in performing administrative tasks. Servers in client/server databases are ordinarily dedicated to making database resources available to client computers. Servers may also be used to run applications for users, in which case the server is called an application server. Peer-to-peer or workgroup servers, such as servers created by using PCs running Windows NT Workstation to share disk folders, are another class of server.
shared application memory Memory that's allocated between processes involved in a lightweight remote procedure call (LRPC). See also LRPC.
shortcut key A key combination that provides access to a menu choice, macro, or other function of the application in lieu of selection with the mouse.
SID An acronym for security ID, a numeric value that identifies a logged-on user who has been authenticated by Windows NT or a user group.
SLIP An abbreviation for Serial Line Interface Protocol, the first common method of connecting via a modem to TCP/IP networks, now less widely used. See PPP.
SMB An abbreviation for Server Message Block, a networking protocol used by NetBEUI to implement Microsoft Networking.
SMP An abbreviation for symmetric multiprocessing, implemented in Windows NT, which distributes tasks among CPUs using a load-sharing methodology. Applications must be multithreaded to take advantage of SMP. See asymmetric multiprocessing.
SNMP An abbreviation for Simple Network Management Protocol, an Internet standard that defines methods for remotely managing active network components such as hubs, routers, and bridges.
source code The readable form of code that you create in a high-level programming language. Source code is converted to machine-language object code by a compiler or interpreter.
source document A term used by OLE 1.0 to refer to a compound object in a container document.
SQL An acronym, pronounced either as "sequel" or "seekel," for Structured Query Language, a language developed by IBM Corporation for processing data contained in mainframe computer databases. (Sequel is the name of a language, similar to SQL, developed by IBM but no longer in use.) SQL has now been institutionalized by the creation of an ANSI standard for the language.
stack See protocol stack.
stored procedure A set of SQL statements (and with those RDBMSs that support them, flow-control statements) that are stored under a procedure name so that the statements can be executed as a group by the database server. Some RDBMSs, such as Microsoft and Sybase SQL Server, precompile stored procedures so that they execute more rapidly. Jet 3.0's Remote Data Object is optimized for use with stored procedures.
stripe set See disk striping and fault tolerance.
Structured Query Language See SQL.
subnet mask A local bit mask (set of flags) that specifies which bits of the IP address specify a particular IP network or a host within a subnetwork. An IP address of 128.66.12.1 with a subnet mask of 255.255.255.0 specifies host 1 on subnet 128.66.12.0. The subnet mask determines the maximum number of hosts on a subnetwork.
synchronous I/O An input/output method in which the process that issues an I/O request waits for the requested process to complete before returning control to the application or operating system. See asynchronous I/O.
system administrator The individual(s) responsible for the administrative functions for all applications on a LAN or users of a UNIX cluster or network, usually including supervision of all databases on servers attached to the LAN. If the system administrator's (SA's) responsibility is limited to databases, the term database administrator (DBA) is ordinarily assigned.
system databases Databases that control access to databases on a server or across a LAN. Microsoft SQL Server has three system databases: the master database, which controls user databases; tempdb, which holds temporary tables; and model, which is used as the skeleton to create new user databases. Any database that's not a user database is a system database.
T-1 The most common moderate-speed telecommunications connection between LANs to create a WAN. Dedicated T-1 lines provide 1.544mbps of bandwidth. T-1 lines also are the most common method of connecting servers to the Internet.
table A database object consisting of a collection of rows (records) divided into columns (fields) that contain data or null values. A table is treated as a database object.
TCP/IP Abbreviation for Transport Control Protocol/Internet Protocol, the networking protocol of the Internet, UNIX networks, and the preferred protocol for Windows NT networks. TCP/IP is a routable network that supports subnetworks. See IP.
TDI An abbreviation for Transport Driver Interface, used by Windows NT to implement multiple network protocols by using various network interface cards.
thread A part of a process, such as an executing application, that can run as an object or an entity. Threads of execution are basis of Windows NT's symmetrical multiprocessing capability. See multiprocessing and SMP.
three-tier The architecture of a database application, usually involving a client-server RDBMS, where the front-end application is separated from the back-end RDBMS by a middle tier application. The middle tier usually is implemented as a remote Automation server, which implements the database connection, enforces business rules, and handles transfer of data to and from databases of the RDBMS. See business rules and Remote Automation Object.
time stamp The date and time data attributes applied to a disk file when created or edited. Time stamp is a database type for SQL Server and the ODBC API.
toggle A property of an object, such as a check box, that alternates its state when repeatedly clicked with the mouse or activated by a shortcut key combination.
Token Ring A network medium developed by IBM in which each computer in the ring passes a token, which carries network messages, to the adjacent computer. Token Ring provides each computer on the ring with guaranteed capability to transmit at regular intervals; Ethernet doesn't provide such a guarantee. Token Ring is specified by the IEEE-802.5 standard. See Ethernet.
transaction A group of processing steps that are treated as a single activity to perform a desired result. A transaction might entail all the steps necessary to modify the values in or add records to each table involved when a new invoice is created. RDBMSs that are capable of transaction processing usually include the capability to cancel the transaction by a rollback instruction or to cause it to become a permanent part of the tables with the COMMIT or COMMIT TRANSACTION statement.
Transact-SQL A superset of ANSI SQL used by Microsoft and Sybase SQL Server. Transact-SQL includes flow-control instructions, and the capability to define and use stored procedures that include conditional execution and looping.
trap Windows NT's method of intercepting an event (such as an interrupt request or an unexpected result) that occurs during execution of a thread.
trigger A stored procedure that occurs when a user executes an instruction that may affect the referential integrity of a database. Triggers usually occur before the execution of an INSERT, DELETE, or UPDATE statement so that the effect of the statement on referential integrity can be examined by a stored procedure before execution. See also stored procedure.
trust In Windows NT domain terminology, a relationship between domain controllers in which users who are members of the trusted domain can access services on another trusting domain without the need to log on to the trusting domain.
two-phase commit A process applicable to updates to multiple (distributed) databases that prevents a transaction from completing until all the distributed databases acknowledge that the transaction can be completed. The replication process has supplanted two-phase commit in most of today's distributed client/server RDBMSs. See replication.
UNC An abbreviation for Unified Naming Convention, the method of identifying the location of files on a remote server. UNC names begin with \\. Windows NT and Windows 95 support UNC; 32-bit Windows applications must support UNC to qualify for application of Microsoft's "Designed for Windows NT" logo. All Microsoft Office 95 and later applications support UNC.
Unicode A replacement for the 7-bit or 8-bit ASCII and ANSI representations of characters with a 16-bit model that allows a wider variety of characters to be used. Unicode is especially useful for representing the written characters of Asian languages. Windows NT and Windows 95 support Unicode.
uniform data transfer (UDT) The interprocess communication (IPC) method used by OLE 2+. OLE 1.0 uses DDE for IPC.
unique index An index in which no two key fields or combinations of key fields on which the index is created may have the same value.
UNIX Registered trademark of a multiuser operating system, now administered by the Open Systems Foundation (OSF). Extensions and modifications of UNIX include DEC Ultrix, SCO UNIX, IBM AIX, and similar products.
UPS An abbreviation for uninterruptible power supply, a device used to power a computer in the event of a primary power outage.
user mode The processor mode used by Windows NT to run applications launched by users. Threads running in user mode are restricted to calling system services. See kernel mode.
UTP An abbreviation for unshielded twisted pair, the type of cabling used to implement 10BaseT and 100BaseT network media.
VBA An abbreviation for Visual Basic for Applications, the official name of which is "Visual Basic, Applications Edition." VBA is Microsoft's common application programming (macro) language for Access, Excel, Project, and the Visual Basic programming environment.
VDM Abbreviation for virtual DOS machine, a Windows NT protected subsystem for running DOS applications in a console window.
virtual address space The range of unique virtual memory addresses allocated to the threads of a single Windows NT process. See VM.
view The method by which the data is presented for review by the user, usually on the computer display. Views can be created from subsets of columns from one or more tables by implementing the SQL CREATE VIEW instruction.
Visual Basic for Applications See VBA.
VM Abbreviation for virtual memory, a method of mapping a combination of RAM and images of RAM stored in a paging file to provide an address space larger than that available from the RAM installed in the computer.
VM manager The Windows NT executive service that loads memory images stored in a paging file on demand, as well as saves memory images in the paging file when no longer needed by a thread.
VPN An abbreviation for Virtual Private Network, a means of establishing secure communication channels on the Internet using various forms of encryption. See PPTP.
WAN An acronym for wide area network. A WAN is a system for connecting multiple computers in different geographical locations by switched telephone network or leased data lines; by optical or other long-distance cabling; or by infrared, radio, or satellite links.
WDM An abbreviation of Windows Driver Model, a 32-bit architecture for creating device drivers that run under both Windows NT and Windows 95. Microsoft hadn't issued the WDM specification when Windows NT 4.0 was released.
Win32 An API for running 32-bit Windows applications under Windows NT and Windows 95. The Win32 APIs of Windows NT and Windows 95 vary. To use Microsoft's "Designed for Windows NT" logo, applications must run under Windows NT 4.0 and Windows 95.
Win32S A subset of the Win32 API designed to add limited 32-bit capabilities to Windows 3.1+. Very few applications have been written to the Win32S API, which appears to have become obsolete.
WINS An acronym for Windows Internet Naming Service, a proprietary Microsoft application that maps easily remembered Windows machine names to the corresponding IP addresses.
Winsock An abbreviation for Windows Sockets, a networking API for implementing Windows applications that use TCP/IP, such as FTP and Telnet.
working set The set of active virtual memory pages for a process stored in RAM at a given instant.
workstation A client computer on a LAN or WAN that is used to run applications and is connected to a server from which it obtains data shared with other computers. Workstation is also used to describe a high-priced PC that uses a high-performance microprocessor and proprietary architecture to create what some call an "open" system.
WOSA Acronym for Windows Open Services Architecture, which is the foundation for such APIs as ODBC, MAPI, and TAPI. Microsoft also develops special vertical-market WOSA APIs for banking, financial, and other industries.
WOW An acronym for Windows on Win32, a subsystem of Windows NT that allows 16-bit Windows applications to run in protected memory spaces called virtual DOS machines. See VDM.
Applet
A small Java application that is downloaded by an ActiveX or Java-enabled web browser. Once it has been downloaded, the applet will run on the user's computer. Common applets include financial calculators and web drawing programs.
Application
Computer software that performs a task or set of tasks, such as word processing or drawing. Applications are also referred to as programs.
ASCII
American Standard Code for Information Interchange, an encoding system for converting keyboard characters and instructions into the binary number code that the computer understands.
Bandwidth
The capacity of a networked connection. Bandwidth determines how much data can be sent along the networked wires. Bandwidth is particularly important for Internet connections, since greater bandwidth also means faster downloads.
Binary code
The most basic language a computer understands, it is composed of a series of 0s and 1s. The computer interprets the code to form numbers, letters, punctuation marks, and symbols.
Bit
The smallest piece of computer information, either the number 0 or 1. In short they are called binary digits.
Boot
To start up a computer. Cold boot means restarting computer after the power is turned off. Warm boot means restarting computer without turning off the power.
Browser
Software used to navigate the Internet. Google Chrome, Firefox, Netscape Navigator and Microsoft Internet Explorer are today's most popular browsers for accessing the World Wide Web.
Bug
A malfunction due to an error in the program or a defect in the equipment.
Byte
Most computers use combinations of eight bits, called bytes, to represent one character of data or instructions. For example, the word cat has three characters, and it would be represented by three bytes.
Cache
A small data-memory storage area that a computer can use to instantly re-access data instead of re-reading the data from the original source, such as a hard drive. Browsers use a cache to store web pages so that the user may view them again without reconnecting to the Web.
CAD-CAM
Computer Aided Drawing - Computer Aided Manufacturing. The instructions stored in a computer that will be translated to very precise operating instructions to a robot, such as for assembling cars or laser-cutting signage.
CD-ROM
Compact Disc Read-Only Memory, an optically read disc designed to hold information such as music, reference materials, or computer software. A single CD-ROM can hold around 640 megabytes of data, enough for several encyclopaedias. Most software programs are now delivered on CD-ROMs.
CGI
Common Gateway Interface, a programming standard that allows visitors to fill out form fields on a Web page and have that information interact with a database, possibly coming back to the user as another Web page. CGI may also refer to Computer-Generated Imaging, the process in which sophisticated computer programs create still and animated graphics, such as special effects for movies.
Chat
Typing text into a message box on a screen to engage in dialogue with one or more people via the Internet or other network.
Chip
A tiny wafer of silicon containing miniature electric circuits that can store millions of bits of information.
Client
A single user of a network application that is operated from a server.A client/server architecture allows many people to use the same data simultaneously. The program's main component (the data) resides on a centralized server, with smaller components (user interface) on each client.
Cookie
A text file sent by a Web server that is stored on the hard drive of a computer and relays back to the Web server things about the user, his or her computer, and/or his or her computer activities.
CPU
Central Processing Unit.The brain of the computer.
Cracker
A person who breaks in to a computer through a network, without authorization and with mischievous or destructive intent.
Crash
A hardware or software problem that causes information to be lost or the computer to malfunction. Sometimes a crash can cause permanent damage to a computer.
Cursor
A moving position-indicator displayed on a computer monitor that shows a computer operator where the next action or operation will take place.
Cyberspace
Slang for internet ie. An international conglomeration of interconnected computer networks. Begun in the late 1960s, it was developed in the 1970s to allow government and university researchers to share information. The Internet is not controlled by any single group or organization. Its original focus was research and communications, but it continues to expand, offering a wide array of resources for business and home users.
Database
A collection of similar information stored in a file, such as a database of addresses. This information may be created and stored in a database management system (DBMS).
Debug
Slang. To find and correct equipment defects or program malfunctions.
Default
The pre-defined configuration of a system or an application. In most programs, the defaults can be changed to reflect personal preferences.
Desktop
The main directory of the user interface. Desktops usually contain icons that represent links to the hard drive, a network (if there is one), and a trash or recycling can for files to be deleted. It can also display icons of frequently used applications, as requested by the user.
Desktop publishing
The production of publication-quality documents using a personal computer in combination with text, graphics, and page layout programs.
Directory
A repository where all files are kept on computer.
Disk
Two distinct types. The names refer to the media inside the container:
A hard disc stores vast amounts of data. It is usually inside the computer but can be a separate peripheral on the outside. Hard discs are made up of several rigid coated metal discs. Currently, hard discs can store 15 to 30 Gb (gigabytes).
A floppy disc, 3.5" square, usually inserted into the computer and can store about 1.4 megabytes of data. The 3.5" square floppies have a very thin, flexible disc inside. There is also an intermediate-sized floppy disc, trademarked Zip discs, which can store 250 megabytes of data.
Disk drive
The equipment that operates a hard or floppy disc.
Domain
Represents an IP (Internet Protocol) address or set of IP addresses that comprise a domain. The domain name appears in URLs to identify web pages or in email addresses. For example, the email address for the First Lady is [email protected], whitehouse.gov, being the domain name. Each domain name ends with a suffix that indicates what top level domain it belongs to. These are : .com for commercial, .gov for government, .org for organization, .edu for educational institution, .biz for business, .info for information, .tv for television, .ws for website. Domain suffixes may also indicate the country in which the domain is registered. No two parties can ever hold the same domain name.
Domain name
The name of a network or computer linked to the Internet. Domains are defined by a common IP address or set of similar IP (Internet Protocol) addresses.
Download
The process of transferring information from a web site (or other remote location on a network) to the computer. It is possible to download a file which include text, image, audio, video and many others.
DOS
Disk Operating System. An operating system designed for early IBM-compatible PCs.
Drop-down menu
A menu window that opens vertically on-screen to display context-related options.Also called pop-up menu or pull-down menu.
DSL
Digital Subscriber Line, a method of connecting to the Internet via a phone line. A DSL connection uses copper telephone lines but is able to relay data at much higher speeds than modems and does not interfere with telephone use.
DVD
Digital Video Disc. Similar to a CD-ROM, it stores and plays both audio and video.
E-book
An electronic (usually hand-held) reading device that allows a person to view digitally stored reading materials.
Electronic mail; messages, including memos or letters, sent electronically between networked computers that may be across the office or around the world.
Emoticon
A text-based expression of emotion created from ASCII characters that mimics a facial expression when viewed with your head tilted to the left. Here are some examples:
- Smiling
- Frowning
- Winking
- Crying
Encryption
The process of transmitting scrambled data so that only authorized recipients can unscramble it. For instance, encryption is used to scramble credit card information when purchases are made over the Internet.
Ethernet
A type of network.
Ethernet card
A board inside a computer to which a network cable can be attached.
File
A set of data that is stored in the computer.
Firewall
A set of security programs that protect a computer from outside interference or access via the Internet.
Folder
A structure for containing electronic files. In some operating systems, it is called a directory.
Fonts
Sets of typefaces (or characters) that come in different styles and sizes.
Freeware
Software created by people who are willing to give it away for the satisfaction of sharing or knowing they helped to simplify other people's lives. It may be free-standing software, or it may add functionality to existing software.
FTP
File Transfer Protocol, a format and set of rules for transferring files from a host to a remote computer.
Gigabyte (GB)
1024 megabytes.Also called gig.
Glitch
The cause of an unexpected malfunction.
Gopher
An Internet search tool that allows users to access textual information through a series of menus, or if using FTP, through downloads.
GUI
Graphical User Interface, a system that simplifies selecting computer commands by enabling the user to point to symbols or illustrations (called icons) on the computer screen with a mouse.
Groupware
Software that allows networked individuals to form groups and collaborate on documents, programs, or databases.
Hacker
A person with technical expertise who experiments with computer systems to determine how to develop additional features. Hackers are occasionally requested by system administrators to try and break into systems via a network to test security. The term hacker is sometimes incorrectly used interchangeably with cracker. A hacker is called a white hat and a cracker a black hat.
Hard copy
A paper printout of what you have prepared on the computer.
Hard drive
Another name for the hard disc that stores information in a computer.
Hardware
The physical and mechanical components of a computer system, such as the electronic circuitry, chips, monitor, disks, disk drives, keyboard, modem, and printer.
Home page
The main page of a Web site used to greet visitors, provide information about the site, or to direct the viewer to other pages on the site.
HTML
Hypertext Markup Language, a standard of text markup conventions used for documents on the World Wide Web. Browsers interpret the codes to give the text structure and formatting (such as bold, blue, or italic).
HTTP
Hypertext Transfer Protocol, a common system used to request and send HTML documents on the World Wide Web. It is the first portion of all URL addresses on the World Wide Web.
HTTPS
Hypertext Transfer Protocol Secure, often used in intracompany internet sites. Passwords are required to gain access.
Hyperlink
Text or an image that is connected by hypertext coding to a different location.By selecting the text or image with a mouse, the computer jumps to (or displays) the linked text.
Hypermedia
Integrates audio, graphics, and/or video through links embedded in the main program.
Hypertext
A system for organizing text through links, as opposed to a menu-driven hierarchy such as Gopher. Most Web pages include hypertext links to other pages at that site, or to other sites on the World Wide Web.
Icons
Symbols or illustrations appearing on the computer screen that indicate program files or other computer functions.
Input
Data that goes into a computer device.
Input device
A device, such as a keyboard, stylus and tablet, mouse, puck, or microphone, that allows input of information (letters, numbers, sound, video) to a computer.
Instant messaging (IM)
A chat application that allows two or more people to communicate over the Internet via real-time keyed-in messages.
Interface
The interconnections that allow a device, a program, or a person to interact. Hardware interfaces are the cables that connect the device to its power source and to other devices. Software interfaces allow the program to communicate with other programs (such as the operating system), and user interfaces allow the user to communicate with the program (e.g., via mouse, menu commands, icons, voice commands, etc.).
Internet
An international conglomeration of interconnected computer networks. Begun in the late 1960s, it was developed in the 1970s to allow government and university researchers to share information. The Internet is not controlled by any single group or organization. Its original focus was research and communications, but it continues to expand, offering a wide array of resources for business and home users.
IP (Internet Protocol) address
An Internet Protocol address is a unique set of numbers used to locate another computer on a network. The format of an IP address is a 32-bit string of four numbers separated by periods. Each number can be from 0 to 255 (i.e., 1.154.10.255). Within a closed network IP addresses may be assigned at random, however, IP addresses of web servers must be registered to avoid duplicates.
Java
An object-oriented programming language designed specifically for programs (particularly multimedia) to be used over the Internet. Java allows programmers to create small programs or applications (applets) to enhance Web sites.
JavaScript/ECMA script
A programming language used almost exclusively to manipulate content on a web page. Common JavaScript functions include validating forms on a web page, creating dynamic page navigation menus, and image rollovers.
Kilobyte (K or KB)
Equal to 1,024 bytes.
Linux
A UNIX - like, open-source operating system developed primarily by Linus Torvalds. Linux is free and runs on many platforms, including both PCs and Macintoshes. Linux is an open-source operating system, meaning that the source code of the operating system is freely available to the public. Programmers may redistribute and modify the code, as long as they don't collect royalties on their work or deny access to their code. Since development is not restricted to a single corporation more programmers can debug and improve the source code faster.
Laptop and notebook
Small, lightweight, portable battery-powered computers that can fit onto your lap. They each have a thin, flat, liquid crystal display screen.
Macro
A script that operates a series of commands to perform a function. It is set up to automate repetitive tasks.
Mac OS
An operating system with a graphical user interface, developed by Apple for Macintosh computers. Current System X.1.(10) combines the traditional Mac interface with a strong underlying UNIX. Operating system for increased performance and stability.
Megabyte (MB)
Equal to 1,048,576 bytes, usually rounded off to one million bytes (also called a meg).
Memory
Temporary storage for information, including applications and documents. The information must be stored to a permanent device, such as a hard disc or CD-ROM before the power is turned off, or the information will be lost. Computer memory is measured in terms of the amount of information it can store, commonly in megabytes or gigabytes.
Menu
A context-related list of options that users can choose from.
Menu bar
The horizontal strip across the top of an application's window. Each word on the strip has a context sensitive drop-down menu containing features and actions that are available for the application in use.
Merge
To combine two or more files into a single file.
MHz
An abbreviation for Megahertz, or one million hertz. One MHz represents one million clock cycles per second and is the measure of a computer microprocessor's speed. For example, a microprocessor that runs at 300 MHz executes 300 million cycles per second. Each instruction a computer receives takes a fixed number of clock cycles to carry out, therefore the more cycles a computer can execute per second, the faster its programs run. Megahertz is also a unit of measure for bandwidth.
Microprocessor
A complete central processing unit (CPU) contained on a single silicon chip.
Minimize
A term used in a GUI operating system that uses windows. It refers to reducing a window to an icon, or a label at the bottom of the screen, allowing another window to be viewed.
Modem
A device that connects two computers together over a telephone or cable line by converting the computer's data into an audio signal. Modem is a contraction for the process it performs : modulate-demodulate.
Monitor
A video display terminal.
Mouse
A small hand-held device, similar to a trackball, used to control the position of the cursor on the video display; movements of the mouse on a desktop correspond to movements of the cursor on the screen.
MP3
Compact audio and video file format. The small size of the files makes them easy to download and e-mail. Format used in portable playback devices.
Multimedia
Software programs that combine text and graphics with sound, video, and animation. A multimedia PC contains the hardware to support these capabilities.
MS-DOS
An early operating system developed by Microsoft Corporation (Microsoft Disc Operating System).
Network
A system of interconnected computers.
Open source
Computer programs whose original source code was revealed to the general public so that it could be developed openly. Software licensed as open source can be freely changed or adapted to new uses, meaning that the source code of the operating system is freely available to the public. Programmers may redistribute and modify the code, as long as they don't collect royalties on their work or deny access to their code. Since development is not restricted to a single corporation more programmers can debug and improve the source code faster.
Operating system
A set of instructions that tell a computer on how to operate when it is turned on. It sets up a filing system to store files and tells the computer how to display information on a video display. Most PC operating systems are DOS (disc operated system) systems, meaning the instructions are stored on a disc (as opposed to being originally stored in the microprocessors of the computer). Other well-known operating systems include UNIX, Linux, Macintosh, and Windows.
Output
Data that come out of a computer device. For example, information displayed on the monitor, sound from the speakers, and information printed to paper.
Palm
A hand-held computer.
PC
Personal computer. Generally refers to computers running Windows with a Pentium processor.
PC board
Printed Circuit board, a board printed or etched with a circuit and processors. Power supplies, information storage devices, or changers are attached.
PDA
Personal Digital Assistant, a hand-held computer that can store daily appointments, phone numbers, addresses, and other important information. Most PDAs link to a desktop or laptop computer to download or upload information.
Portable Document Format, a format presented by Adobe Acrobat that allows documents to be shared over a variety of operating systems. Documents can contain words and pictures and be formatted to have electronic links to other parts of the document or to places on the web.
Pentium chip
Intel's fifth generation of sophisticated high-speed microprocessors. Pentium means the fifth element.
Peripheral
Any external device attached to a computer to enhance operation. Examples include external hard drive, scanner, printer, speakers, keyboard, mouse, trackball, stylus and tablet, and joystick.
Personal computer (PC)
A single-user computer containing a central processing unit (CPU) and one or more memory circuits.
Petabyte
A measure of memory or storage capacity and is approximately a thousand terabytes.
Petaflop
A theoretical measure of a computer's speed and can be expressed as a thousand-trillion floating-point operations per second.
Platform
The operating system, such as UNIX, Macintosh, Windows, on which a computer is based.
Plug and play
Computer hardware or peripherals that come set up with necessary software so that when attached to a computer, they are recognized by the computer and are ready to use.
Pop-up menu
A menu window that opens vertically or horizontally on-screen to display context-related options.Also called drop-down menu or pull-down menu.
Power PC
A competitor of the Pentium chip. It is a new generation of powerful sophisticated microprocessors produced from an Apple-IBM-Motorola alliance.
Printer
A mechanical device for printing a computer's output on paper. There are three major types of printer:
· Dot matrix - creates individual letters, made up of a series of tiny ink dots, by punching a ribbon with the ends of tiny wires. (This type of printer is most often used in industrial settings, such as direct mail for labelling.)
· Ink jet - sprays tiny droplets of ink particles onto paper.
· Laser - uses a beam of light to reproduce the image of each page using a magnetic charge that attracts dry toner that is transferred to paper and sealed with heat.
Program
A precise series of instructions written in a computer language that tells the computer what to do and how to do it. Programs are also called software or applications.
Programming language
A series of instructions written by a programmer according to a given set of rules or conventions (syntax). High-level programming languages are independent of the device on which the application (or program) will eventually run; low-level languages are specific to each program or platform. Programming language instructions are converted into programs in language specific to a particular machine or operating system (machine language). So that the computer can interpret and carry out the instructions. Some common programming languages are BASIC, C, C++, dBASE, FORTRAN, and Perl.
Puck
An input device, like a mouse. It has a magnifying glass with crosshairs on the front of it that allows the operator to position it precisely when tracing a drawing for use with CAD-CAM software.
Pull-down menu
A menu window that opens vertically on-screen to display context-related options.Also called drop-down menu or pop-up menu.
Push technology
Internet tool that delivers specific information directly to a user's desktop, eliminating the need to surf for it. PointCast, which delivers news in user-defined categories, is a popular example of this technology.
QuickTime
Audio-visual software that allows movie-delivery via the Internet and e-mail. QuickTime images are viewed on a monitor.
RAID
Redundant Array of Inexpensive Disks, a method of spreading information across several disks set up to act as a unit, using two different techniques:
· Disk striping - storing a bit of information across several discs (instead of storing it all on one disc and hoping that the disc doesn't crash).
· Disk mirroring - simultaneously storing a copy of information on another disc so that the information can be recovered if the main disc crashes.
RAM
Random Access Memory, one of two basic types of memory. Portions of programs are stored in RAM when the program is launched so that the program will run faster. Though a PC has a fixed amount of RAM, only portions of it will be accessed by the computer at any given time. Also called memory.
Right-click
Using the right mouse button to open context-sensitive drop-down menus.
ROM
Read-Only Memory, one of two basic types of memory. ROM contains only permanent information put there by the manufacturer. Information in ROM cannot be altered, nor can the memory be dynamically allocated by the computer or its operator.
Scanner
An electronic device that uses light-sensing equipment to scan paper images such as text, photos, and illustrations and translate the images into signals that the computer can then store, modify, or distribute.
Search engine
Software that makes it possible to look for and retrieve material on the Internet, particularly the Web. Some popular search engines are Alta Vista, Google, HotBot, Yahoo!, Web Crawler, and Lycos.
Server
A computer that shares its resources and information with other computers, called clients, on a network.
Shareware
Software created by people who are willing to sell it at low cost or no cost for the gratification of sharing. It may be freestanding software, or it may add functionality to existing software.
Software
Computer programs; also called applications.
Spider
A process search engines use to investigate new pages on a web site and collect the information that needs to be put in their indices.
Spreadsheet
Software that allows one to calculate numbers in a format that is similar to pages in a conventional ledger.
Storage
Devices used to store massive amounts of information so that it can be readily retrieved. Devices include RAIDs, CD-ROMs, DVDs.
Streaming
Taking packets of information (sound or visual) from the Internet and storing it in temporary files to allow it to play in continuous flow.
Stylus and tablet
An input device similar to a mouse. The stylus is pen shaped. It is used to draw on a tablet (like drawing on paper) and the tablet transfers the information to the computer. The tablet responds to pressure. The firmer the pressure used to draw, the thicker the line appears.
Surfing
Exploring the Internet.
Surge protector
A controller to protect the computer and make up for variances in voltage.
Telnet
A way to communicate with a remote computer over a network.
Trackball
Input device that controls the position of the cursor on the screen; the unit is mounted near the keyboard, and movement is controlled by moving a ball.
Terabytes (TB)
A thousand gigabytes.
Teraflop
A measure of a computer's speed. It can be expressed as a trillion floating-point operations per second.
Trojan Horse
See virus.
UNIX
A very powerful operating system used as the basis of many high-end computer applications.
Upload
The process of transferring information from a computer to a web site (or other remote location on a network).To transfer information from a computer to a web site (or other remote location on a network).
URL
Uniform Resource Locator.
- The protocol for identifying a document on the Web.
- A Web address (e.g., www.tutorialspoint.com). A URL is unique to each user. See also domain.
UPS
Universal Power Supply or Uninterruptible Power Supply.An electrical power supply that includes a battery to provide enough power to a computer during an outage to back-up data and properly shut down.
USB
A multiple-socket USB connector that allows several USB-compatible devices to be connected to a computer.
USENET
A large unmoderated and unedited bulletin board on the Internet that offers thousands of forums, called newsgroups. These range from newsgroups exchanging information on scientific advances to celebrity fan clubs.
User friendly
A program or device whose use is intuitive to people with a non-technical background.
Video teleconferencing
A remote "face-to-face chat," when two or more people using a webcam and an Internet telephone connection chat online. The webcam enables both live voice and video.
Virtual reality (VR)
A technology that allows one to experience and interact with images in a simulated three-dimensional environment. For example, you could design a room in a house on your computer and actually feel that you are walking around in it even though it was never built. (The Holodeck in the science-fiction TV series Star Trek : Voyager would be the ultimate virtual reality.) Current technology requires the user to wear a special helmet, viewing goggles, gloves, and other equipment that transmits and receives information from the computer.
Virus
An unauthorized piece of computer code attached to a computer program or portions of a computer system that secretly copies itself from one computer to another by shared discs and over telephone and cable lines. It can destroy information stored on the computer, and in extreme cases, can destroy operability. Computers can be protected from viruses if the operator utilizes good virus prevention software and keeps the virus definitions up to date. Most viruses are not programmed to spread themselves. They have to be sent to another computer by e-mail, sharing, or applications.The worm is an exception, because it is programmed to replicate itself by sending copies to other computers listed in the e-mail address book in the computer. There are many kinds of viruses, for example:
· Boot viruses place some of their code in the start-up disk sector to automatically execute when booting. Therefore, when an infected machine boots, the virus loads and runs.
· File viruses attached to program files (files with the extension .exe). When you run the infected program, the virus code executes.
· Macro viruses copy their macros to templates and/or other application document files.
· Trojan Horse is a malicious, security-breaking program that is disguised as something being such as a screen saver or game.
· Worm launches an application that destroys information on your hard drive. It also sends a copy of the virus to everyone in the computer's e-mail address book.
WAV
A sound format (pronounced wave) used to reproduce sounds on a computer.
Webcam
A video camera/computer setup that takes live images and sends them to a Web browser.
Window
A portion of a computer display used in a graphical interface that enables users to select commands by pointing to illustrations or symbols with a mouse. "Windows" is also the name Microsoft adopted for its popular operating system.
World Wide Web ("WWW" or "the Web")
A network of servers on the Internet that use hypertext-linked databases and files. It was developed in 1989 by Tim Berners-Lee, a British computer scientist, and is now the primary platform of the Internet. The feature that distinguishes the Web from other Internet applications is its ability to display graphics in addition to text.
Word processor
A computer system or program for setting, editing, revising, correcting, storing, and printing text.
Worm
See virus.
WYSIWYG
What You See Is What You Get. When using most word processors, page layout programs (See desktop publishing), and web page design programs, words and images will be displayed on the monitor as they will look on the printed page or web page.
Tutorialspoint. Computer Glossary
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