U dating drives
Unrecognized volumes are not assigned letters, and are usually left untouched by the operating system.
A common problem that occurs with the drive letter assignment is that the letter assigned to a network drive can interfere with the letter of a local volume (like a newly installed CD/DVD drive or a USB stick).
In Windows NT and OS/2, the operating system uses the aforementioned algorithm to automatically assign letters to floppy disk drives, optical disc drives, the boot disk, and other recognized volumes that are not otherwise created by an administrator within the operating system.
Volumes that are created within the operating system are manually specified, and some of the automatic drive letters can be changed.
JP Software's 4DOS command line processor supports drive letters beyond Z: in general, but since some of the letters clash with syntactical extensions of this command line processor, they need to be escaped in order to use them as drive letters.The drive letter order can depend on whether a given disk is managed by a boot-time driver or by a dynamically loaded driver.For example, if the second or third hard disk is of SCSI type and, on DOS, requires drivers loaded through the CONFIG. the controller card does not offer on-board BIOS or using this BIOS is not practical), then the first SCSI primary partition will appear after all the IDE partitions on DOS.Therefore, DOS and for example OS/2 could have different drive letters, as OS/2 loads the SCSI driver earlier.A solution was not to use primary partitions on such hard disks.