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When we try to run our protected mode application under Windows 95 in the same DOS session as Btrieve, Windows tells us that protected mode cannot be entered. Any idea what might be the problem?

April 26, 2017application Btrieve dos mode protected run session Try Windows Windows 95

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When we try to run our protected mode application under Windows 95 in the same DOS session as Btrieve, Windows tells us that protected mode cannot be entered. Any idea what might be the problem?

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Yes. You are running into a limitation of Windows. Windows can only handle one dos-extended program at a time. Unfortunately, this limitation has been formalized in the DPMI spec. You will have the same problem in any DPMI implementation, such as Win 3.1, Win NT, or OS/2. The only solutions are to not use a dos extender for one of the applications; to not run in a DPMI environment (i.e. just boot Win95 to DOS mode); or to use the same dos extender for both applications (not very practical).