Can use a USB flash drive to boot the computer into DOS, but in DOS, it cannot access other partitions except the primary partition of the hard disk. Another problem is that all the programs of DM are also copied to the DOS root directory, but it cannot be used, that is, the hard disk cannot be found. Also, when booting to PE from the USB flash drive, the local hard disk on the computer cannot be found. How to solve this? (Example: boot the machine from the USB flash drive into DOS, then use DM to install the system for a new hard disk computer, and then find that DM cannot be used. Adjust the hard disk to IDE mode, can only find the primary partition, cannot find the logical partition. The USB flash drive is formatted in HDD mode, and the drive letter is considered as C.)

