Glossary - A

 A    

 ABIOS - Advanced BIOS. See BIOS. 

 accumulator - (1) A register in which one operand of an operation can be 
    stored and subsequently replaced by the result of that 
    operation. (T)   (2) In the IBM 3800 Printing Subsystem Models 3 and 
    8, a feature that supplies a separate storage that can hold data in 
    raster form. It can be used either for composing a sheet of data that 
    combines a large amount of variable and constant data, or for storing 
    an electronic overlay in raster form that will be merged with variable 
    data as the sheet is printed. 

 access permission - All access rights a user has regarding an object. (I) 
    

 adapter - A piece of hardware that modifies the system unit to allow it 
    to operate in a particular way, often by connecting the system unit to 
    an external device such as a video monitor. 

 adapter device driver - A device driver that provides hardware-dependent 
    services for an OEM adapter. 

 address space -  (1) The range of addresses available to a program. (A)   
    (2) The area of virtual storage available for a particular job. 

 all points addressable (APA) - In computer graphics, pertaining to the 
    ability to address and display or not display each picture element 
    (pel) on a display surface. 

 anchor block - An area of the internal resources of OS/2 Presentation 
    Manager which is allocated to a process or thread that calls 
    WinInitialize. 

 anchor point - The position or choice from which selection or deselection 
    is extended. 

 APA - All points addressable. 

 API - Application programming interface. 

 application programming interface (API) - A functional interface supplied 
    by the operating system, or by a separately-orderable licensed 
    program, that allows an application program written in a high-level 
    language to use specific data or functions of the operating system or 
    the licensed program. 

 archive flag - In the OS/2 operating system, a flag of files and 
    directories that the operating system uses to determine which files 
    are new or modified. Files with this flag are included when a backup 
    copy is made or when all the files are restored on a hard disk. See 
    flag. 

 area - In computer graphics, a filled shape such as a solid rectangle. 

 ASCIIZ - A string of ASCII characters that is terminated with a byte 
    containing the value 0. 

 aspect ratio - (1) The ratio of the height of a rectangle to its width. A 
    rectangle of width 10 inches and height 5 inches has an aspect ratio 
    of 10/5 or 2.   (2) On a display screen, the ratio of the maximum 
    length of a display line to the maximum length of a display column. 

 asynchronous (ASYNC) - (1) Pertaining to two or more processes that do 
    not depend upon the occurrence of specific events such as common 
    timing signals. (T)   (2) Without regular time relationship; 
    unexpected or unpredictable with respect to the execution of program 
    instructions. 

 atom - A constant that represents a string. Once a string has been 
    defined as an atom, the atom can be used in place of the string to 
    save space. Strings are associated with their respective atoms in an 
    atom table. See integer atom. 

 atom table - A table used to associate atoms with the strings that they 
    represent. This table contains the mechanism by which the presence of 
    a string can be verified. 

 AVIO - Advanced Video Input/Output