MS-DOS boot question

This is a basic DOS question, but it's been awhile since I've had to mess with DOS.

I've created a bootable USB drive so I can boot a laptop. The drive boots as C:, that's the same drive letter as the HDD. I'm booting to DOS so I can perform maintenance, Spinrite, on the HDD. How do I force A: making the HDD available?

I've gotten this result on two laptops - Sony VAIO and Lenovo T61.

The USB has no autoexec.bat or config.sys.

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More about boot question
  1. DOS automatically assigns drive letters on bootup and assigns C to the first hard disk. A and B are reserved for floppy drives. You should then be able to see the other partitions in FDISK. though i dont think you will be able to read any NTFS partitions. I prefer to boot off of an Ubuntu or Fedora live CD or thumbdrive to perform my system maintenance.
  2. on second note....
    the old DOS (M$ version) only supports FAT partition....

    most windows installation nowadays wiill use NTFS by befault... so accessing your Windows drive is impossible.....

    if you really need to access your drive in DOS, you need a few more things:-
    1. know how to configure your CONFIG.SYS on boot disk to ionstall 3rd party driver (eg. NTFS4DOS)
    2. configure your BIOS to do emulate SATA drive to emulate IDE (a.k.a Drive Protocol..... most SATA drive use AHCI protocol..... which is completely different from IDE protocol). which i not going to explain in length....
  3. and one more thing...

    NTFS4DOS is kinda old (and haven't been updated for quite sometime)
    NTFS4DOS is not very reliable... especially if you using those advance feature on NTFS (eg. File Encryption EFS)
  4. Thanks for the replies, but I guess I didn't make it clear. This is a DOS issue. I am booting a computer into DOS, not Windows, not Linux, DOS.

    The computers do not have floppy drives; one has a CDROM, the other doesn't even have that.

    I use Spinrite because it doesn't care what the formatting is on the target drive. Spinrite needs DOS and access to the HDD.

    I need these computers to boot up on A:>. How do I force DOS to assign the USB boot drive to A:, allowing the HDD to be on C:?

    The inelegant solution is to remove the HDD and attach it to a desktop. Which is what I would do if I were working on a Macintosh or a Tivo. Desktops don't seem to have this issue of a USB drive booting up to C: when a HDD is present in the system.
  5. go buy a floppy drive for $7 and that will solve your problem.
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