PC Hardware

Running MS-DOS Applications from Windows

By running MS-DOS in a virtual 8086 machine, Windows remains in memory and active. Therefore Windows functions like Cut, Copy, and Paste can be used between MS-DOS applications and the Windows application. Switching between the MS-DOS application and the Windows application is carried out in the same way as between any two Windows applications, by pressing the ALT and TAB keys at the same time. MS-DOS applications can be run either using the full screen or inside a window. To make an MS-DOS application operate properly, Windows uses a .PIF (Program Information File) to hold the necessary data to set up the virtual machine.

Most MS-DOS applications are provided with their own .PIFs that include the optimum settings. When these are provided, they should be used. Usually, .PIFs are located in the same directory as the program executable file. If no .PIF is provided, Windows will use its default .PIF. If there are problems running the program, or no .PIFs exist, the current .PIF can be modified or a new one created. To create or modify this file, use the .PIF editor utility provided by Windows.

Settings for .PIFs

The following table sets out settings available for MS-DOS .PIFs.

Setting Description
Advanced options Additional options made available by clicking the Advanced button. Options include setting the multitasking priority, adding more memory options, and allowing Windows to quit with the application open.
Close window on exit If box is unchecked, the window will stay open when the application terminates.
Display usage Determines whether the application is to be run in a window or full screen.
Execution Selects whether the program is to be run in the background (with other Windows applications running) or exclusively (suspends all other applications).
Memory Sets the minimum amount of conventional memory required for the application to start. Use 0 for "not needed" and -1 for "no limit."
Optional parameters Includes switches or other command settings.
Program file name Includes the drive, path, and filename of the MS-DOS program.
Startup directory Specifies the working directory for the application.
Video memory Selects text, low graphics, or high graphics. This ensures that Windows sets aside enough memory for the video mode used by the application.
Window title This title will be displayed on the Window title bar.