32-Bit Disk Access and Portable Computers

• Microsoft Windows operating system versions 3.1, 3.11

SUMMARY

32-Bit Disk Access should not be used on battery-operated portable computers that implement power-saving features. Enabling 32-Bit Disk Access on such machines can cause Microsoft Windows version 3.1 to stop responding (hang).

MORE INFORMATION

Enabling 32-Bit Disk Access causes Windows to access the system's hard disk(s) using an Enhanced mode virtual device driver (VxD), which accesses the controller hardware directly. To function correctly, the disk controller must be completely compatible with the standard Western Digital hard disk controller architecture. In most cases, Setup and the VxD's own initialization code properly detects those controllers that are not 100% compatible with the Western Digital standard. The disk controllers used in portable computers are very similar to Western Digital controllers but have extensions used for power management, such as shutting down the disk drive when it hasn't been used for a while or when the machine is placed in suspend mode by the user (typically by pressing a button). Some machines, such as Tandon notebook computers, change the state of the disk controller when the power source is changed from line to battery. Basically, the power management support can change the state of the disk controller without notifying Windows.

Since there is no standard for this hardware, the 32-Bit Disk driver cannot determine when power-management events have occurred or what to do about them. If the driver determines the controller is in a different state than it expected, it will produce an error message. If this message is encountered, 32-Bit Disk Access should be turned off.

If Windows cannot be started in Enhanced mode while 32-Bit Disk Access is enabled, Windows should be started with the command line,

     WIN /D:F

Controllers that support drive spin-down, such as Compaq's 386N computers, should not use 32-Bit Disk Access for similar reasons.

NOTE: To avoid problems with these machines, 32-Bit Disk Access is disabled by default. If the machine is not a portable and does not support spin-down, then 32-Bit Disk Access can be enabled.