Editing BIOS parameter block (section)

=== DOS 7.1 EBPB ===
{{Main|DOS 7.1 EBPB}}
Format of short DOS 7.1 Extended BIOS Parameter Block (60 bytes) for [[FAT32]]:

{| class="wikitable"
|-
! Sector offset
! BPB offset
! Field length
! Description
|-
| <code>0x00B</code> || <code>0x00</code> || 25 BYTEs || [[#DOS 3.31 BPB|DOS 3.31 BPB]]
|-
| <code>0x024</code> || <code>0x19</code> || DWORD || Logical sectors per FAT
|-
| <code>0x028</code> || <code>0x1D</code> || WORD || Mirroring flags etc.
|-
| <code>0x02A</code> || <code>0x1F</code> || WORD || Version
|-
| <code>0x02C</code> || <code>0x21</code> || DWORD || Root directory cluster
|-
| <code>0x030</code> || <code>0x25</code> || WORD || Location of FS Information Sector
|-
| <code>0x032</code> || <code>0x27</code> || WORD || Location of backup sector(s)
|-
| <code>0x034</code> || <code>0x29</code> || 12 BYTEs || Reserved (Boot file name)
|-
| <code>0x040</code> || <code>0x35</code> || BYTE || Physical drive number
|-
| <code>0x041</code> || <code>0x36</code> || BYTE || Flags etc.
|-
| <code>0x042</code> || <code>0x37</code> || BYTE || Extended boot signature (<code>0x28</code>)
|-
| <code>0x043</code> || <code>0x38</code> || DWORD || Volume serial number
|}

Format of full DOS 7.1 Extended BIOS Parameter Block (79 bytes) for [[FAT32]]:

{| class="wikitable"
|-
! Sector offset
! BPB offset
! Field length
! Description
|-
| <code>0x00B</code> || <code>0x00</code> || 25 BYTEs || [[#DOS 3.31 BPB|DOS 3.31 BPB]]
|-
| <code>0x024</code> || <code>0x19</code> || DWORD || Logical sectors per FAT
|-
| <code>0x028</code> || <code>0x1D</code> || WORD || Mirroring flags etc.
|-
| <code>0x02A</code> || <code>0x1F</code> || WORD || Version
|-
| <code>0x02C</code> || <code>0x21</code> || DWORD || Root directory cluster
|-
| <code>0x030</code> || <code>0x25</code> || WORD || Location of FS Information Sector
|-
| <code>0x032</code> || <code>0x27</code> || WORD || Location of backup sector(s)
|-
| <code>0x034</code> || <code>0x29</code> || 12 BYTEs || Reserved (Boot file name)
|-
| <code>0x040</code> || <code>0x35</code> || BYTE || Physical drive number
|-
| <code>0x041</code> || <code>0x36</code> || BYTE || Flags etc.
|-
| <code>0x042</code> || <code>0x37</code> || BYTE || Extended boot signature (<code>0x29</code>)
|-
| <code>0x043</code> || <code>0x38</code> || DWORD || Volume serial number
|-
| <code>0x047</code> || <code>0x3C</code> || 11 BYTEs || Volume label
|-
| <code>0x052</code> || <code>0x47</code> || 8 BYTEs || File-system type
|}