Tutorials - How to boot from DOS
| Summary: |
Information regarding 'booting to DOS' as required for some disinfections.
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| Updated: |
20 March 2002 |
| Author: |
Matt Ham |
| Company: |
Virus Bulletin |
Procedure
Rebooting to DOS may be performed in two different ways. The System diskette method should be used in cases where it is necessary that no virus is active. This is the case for boot-sector disinfection and file virus disinfection. The reboot from Windows method may be used when all that is required is to delete files which are usually in use by Windows. Rebooting to DOS is not possible for Windows NT, 2K or XP.
System diskette method
System diskette: a floppy with sufficient system files on it to boot the machine from. If you do not have one, go to a machine running the same operating system (Win98 etc), and then format a floppy disk in Windows Explorer, but ensure that you check the full, and copy system files check-boxes.
Then, write-protect this disk: to do this, slide the little black square in the corner of the disk, such that the hole is open. (Open=write-protected, closed=write-enabled.)
Once you have created and write-protected the floppy diskette, go to the infected machine. Ensure it is off. Put the disk in, switch the machine on. The machine should boot from the floppy, the process will be relatively slow and involve considerable floppy disk access. If the machine boots into your usual operating system then it may be that your machine is configured not to boot from the floppy drive. In order to set a machine to boot from the floppy drive it is necessary to alter BIOS settings - methods of changing these settings vary between machines but will be described in system or motherboard manuals.
Reboot from Windows method
From the Start menu select the Shut Down option. From here select Restart in MS-DOS mode. Simply opening a DOS box with Windows still active is not sufficient for the deletion of files usually in use by Windows.
