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Table of Contents
Note: This API call is for DOS and Win16 personality only. Use Family API for portability.
Int 21H, AH=1CH
Version
1 and higher
Brief
GET DRIVE PARAMETER BLOCK FOR DEFAULT DRIVE
Family API
Input
AH = 1Fh
Return
AL = sectors per cluster (allocation unit), or FFh if invalid drive
CX = bytes per sector
DX = total number of clusters
DS:BX -> media ID byte (see #01356)
Notes
this call was undocumented prior to the release of DOS 5.0; however, only the DOS 4.0+ version of the DPB has been documented
Format of DOS 1.1 and MS-DOS 1.25 drive parameter block:
| Offset | Size | Description |
|---|---|---|
| 00h | BYTE | sequential device ID |
| 01h | BYTE | logical drive number (0=A:) |
| 02h | WORD | bytes per sector |
| 04h | BYTE | highest sector number within a cluster |
| 05h | BYTE | shift count to convert clusters into sectors |
| 06h | WORD | starting sector number of first FAT |
| 08h | BYTE | number of copies of FAT |
| 09h | WORD | number of directory entries |
| 0Bh | WORD | number of first data sector |
| 0Dh | WORD | highest cluster number (number of data clusters + 1) |
| 0Fh | BYTE | sectors per FAT |
| 10h | WORD | starting sector of directory |
| 12h | WORD | address of allocation table |
Note: the DOS 1.0 table is the same except that the first and last fields are missing; see INT 21/AH=32h for the DOS 2+ version
See also
SeeAlso: AH=32h,AX=7302h
Note
Text based on Ralf Brown Interrupt List Release 61
| osFree Macro Library | |
|---|---|
| Video I/O | @SetMode @SetCurSz @SetCurPos @GetCur @SetPage @ScrollUp @ScrollDn @Scroll @GetChAtr @PutChAtr @PutCh @SetPalet @SetColor @SetDot @GetDot @WrtTTY @VideoState @GetMode @GetDisplay @GetVideoState @GetEGAInfo @Cls |
| Hardware info | @Equipment @MemSize |
| Serial I/O | @AuxInit @AuxSendChar @AuxRecieveChar @AuxStatus |
| Tape I/O | @TapeOn @TapeOff @TapeRead @TapeWrite |
| Keyboard I/O | @KbdStatus @CharIn @CharPeek |
| Printer I/O | @PrnPrint @PrnInit @PrnStatus |
| Disk I/O | @DskReset @DskStatus @DskRead @DskWrite @DskVerify @DskFormat |
| Date and Time | @SetTime @GetTime |
| Mouse | @MouInit @MouShowPointer @MouStatus @MouSetPos @MouSetMickey @MouRegion |
| Memory manager | @ModBlok SET_BLOCK |