Format of BIOS Parameter Block

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Offset	Size	Description
00h	WORD	number of bytes per sector
02h	BYTE	number of sectors per cluster
03h	WORD	number of reserved sectors at start of disk
05h	BYTE	number of FATs
06h	WORD	number of entries in root directory
08h	WORD	total number of sectors for DOS 4.0+, set to zero if partition >32M, then set DWORD at 15h to actual number of sectors
0Ah	BYTE	media ID byte (see #01356)
0Bh	WORD	number of sectors per FAT
---DOS 2.13---
0Dh	WORD	number of sectors per track
0Fh	WORD	number of heads
11h	WORD	number of hidden sectors
---DOS 3.0+ ---
0Dh	WORD	number of sectors per track
0Fh	WORD	number of heads
11h	DWORD	number of hidden sectors
15h	11 BYTEs	reserved
---DOS 4.0+ ---
15h	DWORD	total number of sectors if word at 08h contains zero
19h	6 BYTEs	???
1Fh	WORD	number of cylinders
21h	BYTE	device type
22h	WORD	device attributes (removable or not, etc)
---DR DOS 5+ ---
15h	DWORD	total number of sectors if word at 08h contains zero
19h	6 BYTEs	reserved
---European MS-DOS 4.00---
15h	DWORD	total number of sectors if word at 08h contains zero (however, this DOS does not actually implement >32M partitions)

See Also:

#01395,#01664