Summary

OS/2 Version 2.0 provides support for the execution of Windows applications within the MVDM architecture. This support allows the concurrent execution of multiple Windows applications, using both real mode and standard mode, with DPMI and Windows services provided as required by a Windows kernel.

Windows applications running under OS/2 Version 2.0 are provided with pre-emptive multitasking by the operating system. Full memory protection is also provided for the Windows applications; an errant application may not affect other applications executing in the system. A bug in an application will cause the termination of that application only.

Windows applications may be run under OS/2 Version 2.0 in three ways:

  • Each application may run in its own VDM. This method of execution provides full protection for the application from other processes running in the system, and protects these other processes from errors in the Windows application.

  • Applications may share a VDM, and may be started and controlled within this VDM using the Windows Program Manager. This method of execution provides protection for the Windows applications within the VDM from other processes, and protection for other processes from errors in the Windows VDM's applications. However, the applications within the VDM may affect one another since they share a common address space, just as if they were running natively under DOS/Windows.

  • Windows applications may run "seamlessly" on the Workplace Shell desktop, along with windowed VDMs and Presentation Manager applications. This method of execution is similar to the case of a single application in a VDM, except that the Windows application shares the Workplace Shell desktop rather than running in its own full-screen session.

    Any combination of these three methods may be used concurrently.

    Windows applications may be defined on and started from the Workplace Shell desktop. Where a single application is defined for a VDM, or where the application will run seamlessly, the icon used to represent the application on the desktop is the icon embedded within the Windows program which runs the application.

    During installation of OS/2 Version 2.0 over an existing DOS/Windows 3.0 system, existing applications defined to the Windows Program Manager will be detected and migrated where possible to the OS/2 Version 2.0 Workplace Shell. The installation procedure uses application definition information contained in the Certified Application Database, which is shipped as part of the OS/2 Version 2.0 product.

    OS/2 Version 2.0 allows communication between Windows applications running in the same or different VDMs, and between Windows applications and Presentation Manager applications. This communication is provided through clipboard, DDE and OLE support. Communication between Windows applications using shared memory is also supported, but only where Windows applications are executing in the same VDM.

    In summary, OS/2 Version 2.0 provides an integration platform which allows Windows applications to coexist with one another and with DOS and OS/2 applications in a multitasking, fully protected environment, and which allows these applications to communicate with one another.

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