Another condition that can cause problems on Windows XP is when there are network drives defined, but in an error condition (as they would be on a laptop operating outside the network).
Increasing microcomputer storage capacities led to their introduction, eventually followed by long filenames.
In file systems lacking such naming mechanisms, drive letter assignment proved a useful, simple organizing principle.
SYS directives in order to relocate drive structures into upper memory.) Some DOS application programs do not expect drive letters beyond Z: and will not work with them, therefore it is recommended to use them for special purposes or search drives.
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.
This concept of multiple drive letters sharing a single physical device (optionally with different "views" of it) is not limited to the first floppy drive, but can be utilized for other drives as well by setting up additional block devices for them with the standard DOS DRIVER. This is often done to differentiate them from local drives: by using letters towards the end, it reduces the risk of an assignment conflict.
It is especially true when the assignment is done automatically across a network (usually by a logon script).Some versions of DOS do not assign the drive letter, beginning with C:, to the first active primary partition recognized upon the first physical hard disk, but on the first primary partition recognized of the first hard disk, even if it is not set active.If there is more than one extended partition in a partition table, only the logical drives in the first recognized extended partition type are processed. COM provide a preboot config structure, holding bit flags to select (beside others) between various drive letter assignment strategies.MS-DOS on the Apricot PC assigns letters to hard drives, starting with A:, before considering floppy drives.A system with two of each drive would call the hard drives A: and B:, and the floppies C: and D:.These strategies can be preselected by a user or OEM or be changed by a boot loader on the fly when launching DR-DOS.Under these issues, the boot drive can be different from A: or C: as well.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.The Palm DOS PCMCIA driver stack supports drive letters 0:, 1:, 2:, ... Some Novell network drivers for DOS support up to 32 drive letters under compatible DOS versions.In addition, Novell DOS 7, Open DOS 7.01, and DR-DOS 7.02 genuinely support a CONFIG.