struc bpb
.sectorsize:	resw 1 ; WORD sector size
.clustersects:	resb 1 ; BYTE sector / cluster
.reservedsects:	resw 1 ; WORD reserved sector count
.fatnumber:	resb 1 ; BYTE fat number
.direntries:	resw 1 ; WORD root dir entries
.total:		resw 1 ; WORD total sectors
.mediadesc:	resb 1 ; BYTE media descriptor
.fatsectors:	resw 1 ; WORD sectors / fat
.tracksectors:	resw 1 ; WORD sectors per track
.heads:		resw 1 ; WORD number of sides
.sectoroffset:	resd 1 ; DWORD partition offset
.longtotal:	resd 1 ; DWORD large total sectors
.drivenum:	resb 1 ; BYTE drive number
.signature:	resb 1 ; BYTE 28h
.serial:	resd 1 ; DWORD serial
endstruc