Older Disk Controllers Incompatible with Protected-Mode Driver

ID: Q134298

The information in this article applies to:

Microsoft Windows 95

SYMPTOMS

After you install Windows 95 on a Compaq DeskPro 16 computer (circa 1988), you may receive the following error message:

Your system is not configured for its fastest performance

If you click the Details button, you receive the following message:


   Drive C: using MS-DOS Compatibility mode

CAUSE

Certain older computers with proprietary disk controllers exhibit this behavior. Windows 95 protected-mode disk drivers are not guaranteed to work with IDE controllers using proprietary firmware to access drives.

The proprietary firmware in some older IDE disk controllers is not designed to work correctly with the Windows 95 INT 13 interface.

RESOLUTION

You must disable protected-mode support for older IDE controllers that exhibit this problem. To do so, disable the IDE/ESDI controller in Device Manager.

STATUS

This situation is most likely caused by design changes in Windows 95. Microsoft has confirmed that it is not caused by a problem in Windows 95.

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