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Microsoft KB Archive/101789

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Knowledge Base

Reconstructing BOOTSECT.DOS

Article ID: 101789

Article Last Modified on 11/1/2006


  • Microsoft Windows NT Advanced Server 3.1
  • Microsoft Windows NT Workstation 3.1
  • Microsoft Windows NT Advanced Server 3.1
  • Microsoft Windows NT Workstation 3.5
  • Microsoft Windows NT Workstation 3.51
  • Microsoft Windows NT Workstation 4.0 Developer Edition
  • Microsoft Windows NT Server 3.5
  • Microsoft Windows NT Server 3.51
  • Microsoft Windows NT Server 4.0 Standard Edition

This article was previously published under Q101789

Bootsect.dos is created by Windows NT Setup. The boot sector found in sector 0 of drive C is copied into Bootsect.dos before Setup writes the Windows NT boot sector. (Setup will not overwrite an existing Bootsect.dos.) If you choose a previous operating system, Windows NT executes Bootsect.dos, simulating the previous operating system's normal boot procedure.

Because the information in Bootsect.dos is really created by the previous operating system, it is very difficult to re-create. You must transfer the BIOS parameter block (BPB) from the boot drive (C) at sector 0 into the boot code from the previous operating system and write this into Bootsect.dos. To do this, use the following procedure:

  1. Use the proper utility to regenerate a boot sector for the previous operating system. For example, if the previous operating system is MS-DOS, boot MS-DOS from a floppy disk and run the SYS C: command.
  2. Start Windows NT Setup from the boot floppy disk (this may be disk 1 of the Windows NT floppy disk set, the boot floppy disk for the Windows NT CD-ROM, or may have been created during a setup using WINNT.EXE), and initiate repairs by pressing R at the first Setup screen.
  3. Follow the instructions provided by Setup. When Setup presents you with the list of optional repair tasks, make sure you have enabled the "Verify boot files on your C: drive" item.
  4. Follow instructions until you see a message stating "Setup Repair is complete."

Bootsect.dos should now be restored to its original state. You should be able to boot your previous operating system.

Additional query words: prodnt tshoot repair \\bootss

Keywords: kbsetup KB101789