Upgrading Pre-4.0 Systems with Logical Drive(s) > 32 MB (68176)
The information in this article applies to:
• 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
This article was previously published under Q68176
SUMMARY
Some original equipment manufacturers (OEMs) modified their adaptations of
MS-DOS to provide logical drives larger than 32 megabytes in versions of MS-
DOS earlier than version 4.0. This was usually implemented by using a
sector size larger than the standard value of 512 bytes. This is called
"logical sectoring" because the sector size of the drive is a logical
value; that is, it is dependent on the value in the BIOS parameter block of
the drive for bytes_per_sector. Microsoft MS-DOS versions 4.0 and later do
NOT support this logical sectoring on hard disk drives. A sector size of
512 bytes per sector is assumed on all hard disk drives.
If you have used a version of MS-DOS that uses logical sectoring to create
a logical drive larger than 32 MB and want to upgrade to MS-DOS 4.0 or
later, you MUST either repartition the disk or use the Microsoft MS-DOS
Upgrade SETUP.EXE to convert the hard disk drive.
WARNING: After you upgrade the hard disk drive, booting the previous
version of MS-DOS and writing information to the hard disk drive may result
in data corruption. Returning to the previous version of MS-DOS requires
either repartitioning or using the MS-DOS Upgrade Uninstall feature.
NEC, Toshiba, Wyse, and Zenith are known to use logical sectoring, and
other OEMs may have done this as well. Compaq MS-DOS 3.31 is known to have
implemented large logical drives in the same way as Microsoft MS-DOS 4.0
and later (that is, without logical sectoring) and therefore is version
4.0 compatible.
Modification Type: |
Major |
Last Reviewed: |
5/12/2003 |
Keywords: |
KB68176 |
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