"Seamless" WIN-OS/2 VDM

OS/2 Version 2.0 does not allow a "seamless" WIN-OS/2 VDM to be started from a DOS or OS/2 command prompt, nor is there any programmed interface for starting a "seamless" WIN-OS/2 VDM application from a Presentation Manager application. In addition, a SAVDM or MAVDM cannot be switched to a "seamless" WIN-OS/2 VDM once the virtual DOS machine is running.

The "seamless" WIN-OS/2 VDM execution mode allows Windows applications to run from the Workplace Shell desktop in a manner that is virtually indistinguishable from other OS/2 and DOS applications. Double clicking a "seamless" WIN-OS/2 VDM application icon will cause that application to be run in a window on the Workplace Shell desktop. This single application "seamless" WIN-OS/2 VDM environment will be a separate Windows VDM, where the Program Manager is not visible.

In order to be perceived as a compatible part of the Workplace Shell environment, the "seamless" WIN-OS/2 VDM application's execution must be controllable in the same manner as the execution of other OS/2 and DOS applications. This has several implications:

  • The name of each active "seamless" WIN-OS/2 VDM application will be included in the Workplace Shell Task List.

  • Each "seamless" WIN-OS/2 VDM supports an appropriate context menu.

  • The user is able to cycle through all open Workplace Shell windows in the standard Alt-Esc manner.

  • The minimize/hide icons on Windows applications function consistently with other such icons on the Workplace Shell desktop.

  • The window controls on a "seamless" WIN-OS/2 VDM window operate in the same fashion as analogous Workplace Shell controls. The display style of the window controls on a "seamless" WIN-OS/2 VDM window will be "Windows-style" however.

  • When a "seamless" WIN-OS/2 VDM Windows application terminates, its Workplace Shell window is also terminated.

    This approach allows the appearance of a Windows application executing in a "seamless" WIN-OS/2 VDM to conform as closely as possible to that seen when running in a native DOS/Windows environment, while its behavior is as close as possible to that of a normal Presentation Manager/Workplace Shell application.

    If You can't get a "Seamless" WIN-OS/2 VDM to Work

    Starting a Windows application requires a number of configuration options to be correctly completed prior to starting the application. Failure to do so may result in the application failing to start. This is typically due to one of three problems:

  • Failures that are due to the configuration of the overall OS/2 V2.0 system.

  • Failures that are due to the configuration of the overall Windows environment.

  • Failures that are due to the nature of a particular Windows application.

    The first two classes result from not being "seamless capable"; that is, some part of the system's configuration is not set up properly for "seamless" WIN-OS/2 VDM operation. For example:

  • An OS/2 V2.0 video device driver other than the "seamless" VGA driver is installed.

  • VWIN.SYS is not installed, due to the following line being missing in CONFIG.SYS: DEVICE=C:\OS2\MDOS\VWIN.SYS

  • The Windows video device driver referenced by the SDISPLAY.DRV= statement in SYSTEM.INI file does not point to the "seamless" Windows VGA device driver. The correct entry in the SYSTEM.INI is: SDISPLAY=SWINVGA.DRV

    The third class arises because the "seamless" execution environment will be a SAVDM that runs in standard mode only. This means that real mode Windows applications will not be able to run in "seamless" WIN-OS/2 VDM ("seamless" VDMs). The Workplace Shell is able to gracefully handle the initiation of real mode Windows applications, because it can determine the mode of a Windows application from its program header. Such Windows applications will be automatically initiated in full-screen SAVDMs.

    In addition, groups of applications which depend on the sharing of global Windows memory will not be able to run in a "seamless" WIN-OS/2 VDM, unless it is possible to manually initiate one application in the set and then have that application programmatically spawn the rest of the applications in the set. In theory, this situation should never occur because the casual sharing of Windows global memory is expressly against the Microsoft guidelines for Windows system programming. However, if there are applications that depend on such sharing, the user will have to explicitly know to run them in a full-screen MAVDM.

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