Overview

IBM* OS/2* Version 2.0 is an advanced multitasking, single-user operating system for IBM Personal System/2* computers and other machines equipped with the Intel** 80386** or compatible microprocessors. It inherits a rich set of features from previous versions of OS/2, such as support for multitasking, multiple threads, dynamic linking, interprocess communication, a graphical user interface, and a graphics programming interface. Features such as a High Performance File System, Extended Attributes, and long filenames are also available in OS/2 Version 2.0.

Figure "The New OS/2 Version 2.0 Logo"

Unlike previous versions of OS/2, Version 2.0 takes advantage of the advanced features of the Intel 80386 processor architecture, such as a 32-bit memory model, paged virtual memory, and an enhanced processor instruction set. More extensive use is also made of IBM's Micro Channel* architecture for improved hardware performance.

OS/2 Version 2.0 requires the features of the Intel 80386 or compatible 32-bit microprocessors, and therefore does not run on computers that use the Intel 80286** processor, or its predecessors. In order to maintain compatibility, OS/2 Version 2.0 supports applications written for previous versions of OS/2 by providing both a 16-bit as well as a 32-bit application programming interface, allowing existing applications to execute under OS/2 Version 2.0 without modification. Note, however, that only the 32-bit interface provides the full features and performance of OS/2 Version 2.0, and that while existing OS/2 Version 1.x applications will execute under OS/2 Version 2.0, they must be modified in order to take full advantage of the new features of Version 2.0.

The following new features have been implemented in OS/2 Version 2.0:

  • Support for the Intel 80386 32-bit microprocessor instruction set; the 80386 was previously supported only in 80286 emulation mode.

  • 32-bit memory management.

  • Enhanced hardware exploitation.

  • Increased maximum file and disk partition sizes.

  • Multiple Virtual DOS Machines.

  • Support for Windows** applications.

  • New graphical installation program, which includes the ability to install from a local area network (LAN) server.

  • New, portable 32-bit programming environment.

  • Binary compatibility with previous versions of OS/2, allowing 16-bit applications written for previous versions to execute under Version 2.0 without modification.

  • An enhanced Presentation Manager* user shell, known as the Workplace Shell*, which implements the 1991 IBM Systems Application Architecture* (SAA*) Common User Access (CUA) Workplace Environment.

  • Implementation of SOM - System Object Model.

    Figure "Evolution of OS/2"

    Many of these new features are described in this document. Others are described in the remaining volumes in the series; see Related Publications.

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