32-bit application

1 definition found

32-bit application - Free On-line Dictionary of Computing (26 May 2007) :

  32-bit application
  
     <architecture, operating system> IBM PC software that runs
     in a 32-bit flat address space.
  
     The term 32-bit application came about because MS-DOS and
     Microsoft Windows were originally written for the Intel 8088
      and 80286 microprocessors.  These are 16 bit
     microprocessors with a segmented address space.  Programs
     with more than 64 kilobytes of code and/or data therefore had
     to switch between segments quite frequently.  As this
     operation is quite time consuming in comparison to other
     machine operations, the application's performance may suffer.
     Furthermore, programming with segments is more involved than
     programming in a flat address space, giving rise to some
     complications in programming languages like "memory models"
     in C and C++.
  
     The shift from 16-bit software to 32-bit software on IBM PC
     clones became possible with the introduction of the Intel 80386
      microprocessor.  This microprocessor and its successors
     support a segmented address space with 16-bit and 32 bit
     segments (more precisely: segments with 16- or 32-bit address
     offset) or a linear 32-bit address space.  For compatibility
     reasons, however, much of the software is nevertheless written
     in 16-bit models.
  
     Operating systems like Microsoft Windows or OS/2 provide
     the possibility to run 16-bit (segmented) programs as well as
     32-bit programs.  The former possibility exists for backward compatibility
      and the latter is usually meant to be used for
     new software development.
  
     See also Win32s.
  
     (1995-12-11)