Booting DOS from the NT OS Loader

sechs

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Anyone have any good instructions on how to add DOS to an existing boot menu? I'm not finding anything clear and useful on this.
 

time

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I'm interested in this as well. The only thing I can think of is to boot from a DOS disk, SYS C drive, then run a Windows repair (assuming we're talking about 2K/XP).

In other words, I don't know how to get a bootable DOS setup without allowing it to overwrite the boot loader.
 

ddrueding

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I'm in the same boat as you guys, but you chould cheat by sticking it on a seperate drive...then just reference it in the boot loader, no?
 

Howell

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This task is much more easily accomplished with a different boot loader. One that can change the active partitions on the fly. The NT boot loader is pretty stupid. The MBR is very similar between NT and DOS. All the NT fancy stuff happens at the next step. You might try LILO or Grub or some other free one. These place more complex code into the MBR which allows more choices before partitions are "live".

Keep in mind that DOS doesn't read NTFS so you will have to have a FAT partition. IIRC, DOS also doesn't like living past cylinder 1024.

FYI,
Microsoft Knowledge Base Article - 101787
 

sechs

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Well, I don't really wish to jack my current system volume just to avoid using a floppy.

I was hoping that there was some way to do this by stealing the boot sector from a floppy, but that doesn't look to be the case.
 

time

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Found this definitive answer: http://www.winimage.com/bootpart.htm

Practical application is described here.

Method 1:
o Copy Bootpart.exe onto the partition you will be booting NT and DOS off.
o Install DOS as per normal. Boot into DOS. Run Bootpart:
o bootpart WINNT BOOT:C: (to turn the MBR back to an NT boot sector)
o bootpart WIN98 bootsect.w98 "Windows 98" (To include a Win98 option in the NT boot menu).

Method 2:
o Boot from a DOS boot disk
o Copy the DOS directory (and IO.SYS & MSDOS.SYS) to the root of your active partition. Run Bootpart:
o bootpart REWRITEROOT:C: (to place IO.SYS and MSDOS.SYS at the beginning of the partition)
o bootpart DOS622 bootsect.622 "MS-DOS 6.22" (To include a DOS option in the NT boot menu)
 

sechs

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Where does the DOS boot sector come from?

My understanding it that the DOS bootsector is partition-specific; meaning that I'd have to install DOS to my boot partition. Other than the aforementioned jacking of my system volume, I'd have to own DOS (I was hoping to convert from the WinME boot floppy that I use).
 
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