Using 32-Bit Disk Access on WD 2540 Hard Disk Drives

This article was previously published under Q113751
This article has been archived. It is offered "as is" and will no longer be updated.
The following article contains information about the use of Windows andWindows for Workgroups with third-party products or configurations thathave not been tested and are not supported by Microsoft.

If the steps or procedures described in this article do not functionproperly, contact the manufacturer of the third-party product formore information or use a supported configuration.
After you enable 32-bit disk access (FastDisk), the system becomes unstableor stops responding (hangs) during startup, or Windows displays one of thefollowing error messages:
  • The Microsoft Windows 32-bit disk driver (WDCTRL) validation failed at phase XX, XX.
  • Windows: This application has tried to access your hard disk in a way that is incompatible with the Windows 32-bit disk access feature (WDCTRL). This may cause your system to become unstable.
  • Insufficient memory or address space to run Windows in Enhanced mode. Remove TSR programs to free memory.
These errors occur when you use a hard disk with more than 1024 cylinders.IDE hard disks must have CMOS settings with the following upper limits touse 32-bit disk access:
   Cylinders:      1024   Heads:          16   Sectors/Track:  63   Bytes/Sector:   512
You can use the Microsoft Diagnostics (MSD) utility to view these settings,or you can examine the CMOS settings for your computer to confirm thevalues for these settings. Please see your hardware documentation forinstructions about accessing your computer's CMOS settings.

If your hard disk is incompatible with 32-bit disk access, you can disablethis feature by following these steps:
  1. In Control Panel, double-click the 386 Enhanced icon.
  2. Choose the Virtual Memory button, then choose Change.
  3. Clear the Use 32-Bit Disk Access check box.
NOTE: You can also disable 32-bit disk access by starting Windows with the/D:F switch, or by setting 32BitDiskAccess to OFF in the [386Enh] sectionof the SYSTEM.INI file.
The following list of workarounds is grouped by manufacturer. If your harddisk does not appear in this list, please contact your hard diskmanufacturer for more information.



The 7546AT Conner drive is a 540 megabyte (MB) drive with 1048 cylinders,16 heads, and 63 sectors per track. Reducing the number of cylinders in theCMOS settings to 1024, then repartitioning and reformatting the disk mayallow 32-bit disk access and 32-bit file access to work.

WARNING: Be sure to back up your data before you repartition or reformatyour hard disk. Repartitioning or reformatting the disk will remove allinformation from the disk.


If you have an IBM ValuePoint computer that supports IDE hard disks withmore than 1024 cylinders, you should download two files from the IBM BBS.The files are VPWINBHF.DSK and LDF.COM. For information about how to enable32-bit disk access using these files, please contact IBM.



To use 32-bit disk access with the Maxtor 7540AV hard disk, you may need toreduce the cylinder count from 1048 to 1024.


To use 32-bit disk access with the Maxtor 7546AT hard disk, you may need toreduce the cylinder count from 1048 to 1024.


The Maxtor 7548AT IDE hard disk drive has 1060 cylinders, 16 heads, and 63sectors per track. Reducing the cylinder count in the CMOS settings to 1024allows 32-bit disk access to work. If you continue to get an error message,you may need to add the NOMOVEXBDA parameter to the EMM386.EXE command inthe CONFIG.SYS file.

For more information about Maxtor hard disks and 32-bit disk accesscompatibility, please contact Maxtor.



The Quantum LPS-540AT hard disk defaults to 1120 cylinders, 59 logicalsectors per track, and 16 heads. According to Quantum technical support,this drive can be configured with 1024 cylinders, 63 logical sectors pertrack, and 16 heads to make this drive compatible with 32-bit disk access.

NOTE: Quantum's BBS has a self-extracting file, IDE_DOS.EXE, that containsan MS-DOS utility that allows the drive to be formatted to 540 megabytes.Included in this file is IDE_WIN.386, which is the Quantum replacement forWDCTRL.

For more information about configuring your Quantum hard disk or aboutusing the files listed above, please contact Quantum.

Samsung SHD-30560A

Samsung recommends 1024 cylinders, 16 heads, and 63 sectors (for a total of528.0 MB) to use 32-bit disk access.

Western Digital


The Western Digital 2420 hard disk is incompatible with 32-bit disk andfile access in Windows. For information about using this hard disk with32-bit disk and file access in Windows, please contact Western Digital.

Caviar WDAC-2540:

Western Digital has confirmed that the Caviar model 2540 516 MB hard diskuses BIOS parameter settings that are incompatible with the 32-bit diskaccess driver (WDCTRL) included with Windows.

To work around this problem, use one of the following methods:
  • If the BIOS in your computer does not support drives with more than 1024 cylinders, download a utility program called WDSWT.COM from the Western Digital BBS. This utility stamps the disk with a parameter translation brand so that it reports 1024 cylinders to the Windows 32-bit disk access driver. This procedure is reversible should the need arise.

    NOTE: WDSWT.COM is for use with the AC2540 drive only. It is not intended for use on the AC2700 (730 MB) or AC31000 (1083 MB) drives.
  • Download the self-extracting file WIN31.EXE from the Western Digital BBS. This file contains the driver WDCDRV.386, which can be used to replace WDCTRL.
  • Update your computer's ROM BIOS to a version that supports logical block addressing (LBA) to automatically translate more than 1024 cylinders.
  • Disable 32-bit disk access.
  • Change the CMOS settings for the drive to 1024 cylinders or fewer, and then run FDISK and reformat the disk. This workaround allows the use of WDCTRL, but results in a loss of 11.8 MB of disk space.

    WARNING: Be sure to back up your data before you repartition or reformat your hard disk. Repartitioning or reformatting the disk will remove all information from the disk.
For more information about these workarounds, please contact WesternDigital.
32-bit disk access is a set of protected-mode device drivers that worktogether to enhance your computer's BIOS. It filters interrupt (INT) 13Hcalls to the hard disk controller and directs them in the most efficientway for the system (either through the 32-bit interface with the hard diskcontroller or through the system BIOS).

In Windows for Workgroups version 3.11, a hard disk that is incompatiblewith 32-bit disk access may still be able to use 32-bit file access. Thelargest performance gain is accomplished using 32-bit file access. Using 32-bit file access provides compatibility with future versions of Windows.

The Windows 32-bit disk access driver (WDCTRL) supports disk controllersthat are compatible with the Western Digital 1003 controller interfacestandard, but is compatible only with hard disks with 1024 or fewercylinders.
For more information about 32-bit disk access, see the Microsoft Windowsfor Workgroups "Resource Kit," version 3.11, pages 1-19.
3.10 3.1 3.11 VFAT dmdrvr.bin disk manager WDCTRL 07, 1F 1F, 071F 540 03, 3f 033f 33f P5-66

Article ID: 113751 - Last Review: 02/28/2014 07:54:50 - Revision: 2.0

Microsoft Windows 3.1 Standard Edition, Microsoft Windows 3.11 Standard Edition, Microsoft Windows for Workgroups 3.1, Microsoft Windows for Workgroups 3.11

  • kbnosurvey kbarchive KB113751