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)
Nearby terms:
2.PAK « 32000 « 3270 « 32-bit application »
3780 » 386 » 386BSD
|
