China DOS Union

What is the difference between loading a USB CD-ROM in DOS and booting from a USB CD-ROM?

What is the difference between booting to DOS and then accessing the USB CD-ROM and booting from the USB CD-ROM and then accessing the USB CD-ROM?

I think there should be no difference. But when actually operating, it seems there are still differences.

There is an existing boot disk, such as that one - key GHOST, which can boot from a normal CD - ROM or use GRUB to boot the floppy disk image inside, and then load the driver program of USB - CD to realize the access to the USB CD - ROM.

But if directly booting from the USB CD - ROM, there are always problems. For example, if that one - key GHOST CD - ROM is booted from the USB CD - ROM, it always prompts that command.com is not found. Manually entering a:\command.com or x:\command.com and so on is also ineffective.

1. Any optical drive requires loading a driver program to be accessible.
2. Booting through an optical drive means that the BIOS finds the boot information of the disc in the optical drive, loads it, and then enters the system (such as the DOS system). But if this system does not load the optical drive driver program, the optical drive still cannot be accessed in this system.
3. The problem that you can't find command.com may occur on the bootloader. When booting into DOS, without loading the USB driver, USB devices cannot be accessed, and loading the USB driver may disrupt the disk sequence established when the BIOS + bootloader calls the optical disc boot information, leading to the loss or disorder of the original location of command.com.
Look:
http://www.cn-dos.net/forum/viewthread.php?tid=46885&fpage=2

[ Last edited by DXSX on 2009-6-16 at 03:56 ]