Format of parameter block for functions 40h, 60h:
Offset Size Description )
00h BYTE special functions
bit 0 set if function to use current BPB, clear if Device
BIOS Parameter Block field contains new default BPB
bit 1 set if function to use track layout fields only
must be clear if CL=60h
bit 2 set if all sectors in track same size (should be set)
bits 3-7 reserved (MS-DOS, Novell DOS 7)
bit 5: skip head settling time (WinDOS 2.11)
bit 6: format access flag (WinDOS 2.11)
01h BYTE device type (see #01561)
02h WORD device attributes
bit 0 set if nonremovable medium
bit 1 set if door lock ("changeline") supported
bits 2-15 reserved
04h WORD number of cylinders
06h BYTE media type
for 1.2M drive
00h 1.2M disk (default)
01h 320K/360K disk
F8h for DUBLDISK.SYS v2.6 expanded drives
always 00h for other drive types
07h 31 BYTEs device BPB (see #01663 at AH=53h), bytes after BPB offset 1Eh
omitted; final six bytes only transferred on function 40h
with BYTE 00h bit 0 set for MS-DOS 5.0
---function 40h only---
26h WORD number of sectors per track (start of track layout field)
(maximum 63)
28h N word pairs: number,size of each sector in track
---category code 48h (FAT32), function 40h---
07h 53 BYTEs extended BPB (see #01664)
3Ch 32 BYTEs reserved
5Ch WORD number of track table entries
5Eh 2N WORDs sector table (word pairs: number/size of each sector in track)
---category code 48h (FAT32), function 60h---
07h 53 BYTEs extended BPB (see #01664)
3Ch 32 BYTEs reserved