Microsoft small business knowledge base

Article ID: 153550 - Last Review: October 26, 2013 - Revision: 2.0

This article was previously published under Q153550
This article has been archived. It is offered "as is" and will no longer be updated.


When you try to partition a drive that is larger than 8 gigabytes (GB) in size, the maximum partition size may be 8 GB.


This behavior can occur if the hard disk controller does not fully support the interrupt 13 extensions. This information applies to both IDE and SCSI hard disk drives.


Contact the drive controller's manufacturer for information about a possible BIOS upgrade to a version of the BIOS that fully supports interrupt 13 extensions.

More information

In order for a hard disk that is larger than 8 GB and uses the FAT32 file system to be fully addressed, it must support interrupt 13 extensions. Io.sys tests for the presence of interrupt 13 extensions. If interrupt 13 extensions are not detected, the default CHS LBA limit of 7.9 GB is used.

To determine whether your BIOS supports interrupt 13 extensions, please refer to your computer's documentation or consult your computer's manufacturer.

Applies to
  • Microsoft Windows 95
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