Microsoft KB Archive/68725

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Hard Drives That Require VirtualHDIrq=off Switch in SYSTEM.INI

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Q68725

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The information in this article applies to:


 * Microsoft Windows versions 3.0, 3.0a

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SUMMARY
Microsoft Windows 3.0 may have problems operating in 386 enhanced mode with some nonstandard hard disks and hard disk controllers. It may be necessary to use the

"VirtualHDIrq=" switch in the SYSTEM.INI file to enable Windows to run in 386 enhanced mode.

MORE INFORMATION
The VirtualHDIrq= switch allows Windows in 386 enhanced mode to terminate interrupts from the hard disk controller, bypassing the ROM routine that handles these interrupts. Some hard drives might require that this setting be disabled in order for interrupts to be processed correctly. If this setting is disabled, the ROM routine handles the interrupts.

To disable Windows from handling the hard disk termination interrupt routines, place the following line in the SYSTEM.INI file under the [386Enh] section:

"VirtualHDIRQ=off" The following is a list of hard drives that are known to require the VirtualHDIrq=off switch in the SYSTEM.INI file:

  Drive                              Size          Type -

Seagate Wren Swift 94354                        ESDI Microscience HH-1090              80 MB         MFM Western Digital (WD) Caviar 280   80 MB         IDE In addition, Ontrack's Disk Manager partitioning utility may need this switch.