Workarounds for the MS-DOS 1024-Cylinder Limit (73033)


The information in this article applies to:
    • Microsoft MS-DOS operating system 3.1
    • Microsoft MS-DOS operating system 3.2
    • Microsoft MS-DOS operating system 3.21
    • Microsoft MS-DOS operating system 3.3
    • Microsoft MS-DOS operating system 3.3a
    • Microsoft MS-DOS operating system 4.0
    • Microsoft MS-DOS operating system 4.01
    • Microsoft MS-DOS operating system 5.0
    • Microsoft MS-DOS operating system 5.0a
    • Microsoft MS-DOS operating system 6.0
    • Microsoft MS-DOS operating system 6.2
    • Microsoft MS-DOS operating system 6.21
    • Microsoft MS-DOS operating system 6.22
    • Microsoft Windows 95
This article was previously published under Q73033

SUMMARY

Because MS-DOS uses the ROM BIOS to access the hard drive, MS-DOS is limited to the standard AT ROM BIOS interface's maximum of 1024 cylinders. It is possible to have a CMOS Setup allow viewing the full number of cylinders but still have the BIOS limited to using only 1024 cylinders.

MORE INFORMATION

There are four methods to work around this problem:
    • Purchase a hard disk controller card that translates the drive's parameters into values acceptable to the ROM BIOS and to MS-DOS. This allows you to partition and format the entire drive with MS-DOS. For information about purchasing such a controller, contact your hard drive or hard drive controller manufacturer.
    • Use a software package to translate the drive's parameters into values acceptable to MS-DOS. Examples of this type translation software include SpeedStor from Storage Dimensions and Disk Manager from OnTrack Software.

    Warning: A side effect of this solution can cause data corruption with most disk caches, including Microsoft's SMARTDRV.SYS. This is why later versions of SMARTDRV.SYS, which were shipped with Windows version 3.00a and MS-DOS version 5.0, refuse to load if the partitions created by these utilities exist. MS-DOS 5.0 allows an override of this safety feature; however, it should not be used if the disk has more than 1024 cylinders and translation software is installed.

    See section 7.5 of the MS-DOS 5 Upgrade README.TXT for more information.
    • Use only the first 1024 cylinders of the disk.
    • Purchase a hard drive with 1024 cylinders or less.
The products included above, Disk Manager and SpeedStor, including their software drivers in the Microsoft MS-DOS 5 Upgrade, are manufactured by vendors independent of Microsoft; we make no warranty, implied or otherwise, regarding these products' performance or reliability. This information is included only for the user's convenience.

MS-DOS 5.x compatible versions of the drivers used by these products are included in the Microsoft MS-DOS 5 Upgrade.
Modification Type: Major Last Reviewed: 5/12/2003
Keywords: KB73033
©2002 Microsoft Corporation. All rights reserved.