<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)

<architecture> The processor chip architecture and instruction set used by Intel in its Pentium processors. (2007-06-17)

IA-32 (short for "Intel Architecture, 32-bit", sometimes also called i386) is the 32-bit version of the x86 instruction set architecture, designed by Intel and first implemented in the 80386 microprocessor in 1985. IA-32 is the first incarnation of x86 that supports 32-bit computing; as a result, the "IA-32" term may be used as a metonym to refer to all x86 versions that support 32-bit computing.