Compatibility: 2.0+?  undoc 
Expects: AH    53H
DS:BX addr of a BIOS Parameter Block (as used by device drivers)
ES:BP addr of buffer to receive a Drive Parameter Block (DPB)
Returns: ES:BX buffer contains a filled-in DPB
Info: This undocumented function is used by DOS during startup to
prepare its chain of DPBs.

DOS issues a DvRq 02H (Build BPB) request to a device driver and
then calls this to put the data into a more useful form.  It then
installs the DPB into a chain of DPBs (see DosVarsRec).

It has no practical use for application programs, but it might be
used by a disk utility or a block device driver which installs
itself from the DOS command line.

See Also: Device Drivers
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DOS Fn 53H: Convert BPB to DPB