Intel 80386 32-Bit Microprocessor Support

The basis for OS/2 Version 2.0 is its support for the Intel 80386 microprocessor; previous versions of OS/2 were developed for the Intel 80286 processor, and supported the 80386 in 80286 emulation mode only. Full support of the 80386 means that a powerful set of 32-bit features now becomes available to the operating system and applications, including enhanced memory management and more sophisticated multitasking capabilities. The Intel 80386 and 80486 offer significant improvements over the previous generation of 16-bit microprocessors, while retaining compatibility with these processors.

The memory addressing capacity of the 80386 processor is significantly greater than that of the 80286:

  • gigabyte (GB) physical address space; this compares with the 640 kilobyte (KB) address space of DOS and the 16 megabyte (MB) address space of OS/2 Version 1.3.

  • 64 terabyte (TB) virtual address space; DOS does not support virtual memory, and OS/2 Version 1.3 supports 2 GB of virtual memory.

  • byte to 4 gigabyte memory objects; this compares with a 64 KB maximum size under DOS or OS/2 Version 1.3.

    OS/2 Version 2.0 uses many of these processor features and capabilities to provide a more powerful and flexible operating system platform. Note that OS/2 Version 2.0 does not implement the full 64 TB virtual address space provided by the 80386, since this requires use of the segmented memory model; OS/2 Version 2.0 uses a flat memory model, as described in Memory Management.


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