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Format of Set_DPBforFormat structure

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Offset Size Description

00h

WORD

(call) size

02h

WORD

(call) structure version??? (0000h)
(ret) ???

04h

DWORD

(call) function number
00h = invalidate DPB counts
01h = rebuild DPB from BPB
02h = force media change (next access to drive rebuild DPB)
03h = get/set active FAT number and mirroring
04h = get/set root directory cluster number

---function 00h---

08h

DWORD

new DPB free count
00000000h = no change
FFFFFFFFh = unknown

0Ch

DWORD

new DPB next-free
00000000h = no change
FFFFFFFFh = unknown

10h

DWORD

unused

14h

DWORD

unused

---function 01h---

08h

DWORD

unused???

0Ch

DWORD

(call) BIOS Parameter Block from which to rebuild DPB

10h

DWORD

unused

14h

DWORD

unused

---function 02h---

08h

DWORD

unused

0Ch

DWORD

unused

10h

DWORD

unused

14h

DWORD

unused

---function 03h---

08h

DWORD

(call) new active FAT/mirroring state, or FFFFFFFFh to get
bits 3-0 : the 0-based FAT number of the active FAT
bits 6-4 : reserved (0)
bit 7 : do not mirror active FAT to inactive FATs

0Ch

DWORD

(ret) previous active FAT/mirroring state (as above)

10h

DWORD

unused

14h

DWORD

unused

---function 04h---

08h

DWORD

(call) new root directory cluster number FFFFFFFFh to get current

0Ch

DWORD

(ret) previous root directory cluster number

10h

DWORD

unused

14h

DWORD

unused