Monitoring legacy programs

This topic describes how to monitor a 16-bit Windows-based program or an MS-DOS-based program.

In , 16-bit Windows-based programs run as separate threads in a multithreaded process called Windows Virtual DOS Machine (NTVDM). The NTVDM process simulates a 16-bit Windows environment. An MS-DOS-based program runs in its own NTVDM process.

You can monitor a 16-bit program or an MS-DOS-based program running on your computer with System Monitor by monitoring the ntvdm instance of the Process performance object. Note that 16-bit programs running in an NTVDM appear only if they are started in a separate memory space.

If you find that your 16-bit programs are not performing well under , you can access some of the program's properties by right-clicking the name of the program in Windows Explorer and configuring the properties as follows:

If the program is in a window and the display performance is slow, on the Screen tab, click Full-Screen.

If the program is in a window and seems to pause periodically, click the Misc tab, and set the Idle Sensitivity slider to Low.

It is possible to turn off Compatible Timer Hardware Emulation for the program if performance does not improve by changing the previously described settings. To do so, right-click _Default.pif or the program name, point to Program, and click Windows NT. In the dialog box that appears, clear the Compatible Timer Hardware Emulation check box. This change typically causes a decrease in performance and should be made only if other efforts fail.

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