Partition shows up as an MS-DOS partition

Updated: 05/05/2017 by Computer Hope

A DDO or Disk Drive Overlay is being used

A DDO or Disk Drive Overlay is a TSR that loads onto sector two of the hard drive. It is used for computers that do not support LBA mode and allows them to "see" larger than 520 MB. A DDO can also be used to setup a hard drive on a computer. If your machine boots from a diskette, and your partitions are displayed as MS-DOS partitions, it is likely that a DDO is present on the computer.

To find out if a DDO is present on the computer, first remove all diskettes from the computer. Then, boot the computer and see if any message appears asking you to press a key sequence, such as Ctrl+Esc, to boot from a diskette. If this message is displayed or a similar message it is likely that a DDO is loading.

To see the partitions correctly, wait for this message and press the key sequence once asked to boot from a diskette. Once the appropriate keys are pressed, the computer will prompt you to then insert the bootable diskette.

Windows NT or other operating system is installed

If a partition that does not use the FAT system is loaded into the computer, FDISK displays the partitions as an MS-DOS partition. Operating Systems that do not apply to this rule are MS-DOS 5.0 and above, Windows 3.x, Windows 95, Windows 98, and Windows ME. If any other operating system has been loaded onto the computer it is likely that a different file structure is being used such as NTFS or HPFS.

Partition was setup as an MS-DOS partition

MS-DOSIf a partition has been setup through fdisk as an MS-DOS partition it shows as an MS-DOS partition. If you have not setup the partition to be an MS-DOS partition see other possibilities.

If you have created a partition in fdisk as MS-DOS partition use fdisk to delete that MS-DOS partition and recreate the partition as a Primary partition or Extended Logical partition.

Note: If you are currently running an installed copy of MS-DOS 5.0 and above, or Windows 3.x, 95, 98, or ME, it is likely that the partition was not setup as an MS-DOS partition.

A save to partition utility such as Phdisk is present on the hard drive

If your computer is a laptop computer and using Windows 3.x, Windows 95, Windows 98, or Windows NT, your computer may be using a save to file utility such as Phdisk. This utility is designed to save information you may be working on when it goes into sleep mode or when your battery is low on power. This partition will be a small section of the hard drive and you should have another partition setup as a Primary partition or Extended Logical partition that contains your operating system.

If you do not have a laptop or all partitions are being displayed as an MS-DOS partition, refer to another possibility.

Computer virus is on the computer

If you believe that none of the above possibilities are causing your computer to show as an MS-DOS partition it is likely that the computer may be infected by a computer virus. If you have a virus scanner verify it is up-to-date and that you scan your computer for any viruses that can be cleaned on the computer.

If no antivirus protection is installed or you cannot update the antivirus we suggest deleting and recreating all partitions and then re-installing all software.

Additional information

  • See the fdisk command page for further information about this command.