dosints.txt

DOS核心中断的详细讲解

 1Ch	DWORD	network ID
---SHARE not loaded, local device---
 1Ah	DWORD	pointer to device driver header (see #1511)
 1Eh  2 BYTEs	unused???
---SHARE not loaded, local file---
 1Ah	BYTE	extra info
		bit 7: read-only attribute from SFT
		bit 6: archive attribute from SFT
		bits 5-0: high bits of sector number
 1Bh	WORD	starting cluster of file
 1Dh	WORD	low word of sector number containing directory entry
		(see #1217)
 1Fh	BYTE	number of directory entry within sector
--------D-2110-------------------------------
INT 21 - DOS 1+ - CLOSE FILE USING FCB
	AH = 10h
	DS:DX -> File Control Block (see #1210)
Return: AL = status
	    00h successful
	    FFh failed
Notes:	a successful close forces all disk buffers used by the file to be
	  written and the directory entry to be updated
	not supported by MS Windows 3.0 DOSX.EXE DOS extender
SeeAlso: AH=0Fh,AH=16h,AH=3Eh
--------D-2111-------------------------------
INT 21 - DOS 1+ - FIND FIRST MATCHING FILE USING FCB
	AH = 11h
	DS:DX -> unopened FCB (see #1210), may contain '?' wildcards
Return: AL = status
	    00h successful
		[DTA] unopened FCB for first matching file
	    FFh no matching filename, or bad FCB
Notes:	the type of the returned FCB depends on whether the input FCB was a
	  normal or an extended FCB
	the data returned in the DTA (disk transfer area) is actually the
	  drive number (or extended FCB header and drive number) followed by
	  the file's directory entry (see #1217); this format happens to be
	  compatible with an unopened FCB
	for extended FCBs with search attribute 08h, the volume label (if any)
	  will be returned even if the current directory is not the root dir.
	DOS 3.0+ also allows the '*' wildcard
	the search FCB must not be modified if AH=12h will be used to continue
	  searching; DOS 3.3 has set the following parts of the FCB:
		 0Ch	BYTE	???
		 0Dh	WORD	directory entry number of matching file
		 0Fh	WORD	cluster number of current directory
		 11h  4 BYTEs	???
		 15h	BYTE	drive number (1=A:)
	this function is used by many copy protection schemes to obtain the
	  starting cluster of a file
SeeAlso: AH=12h,AH=1Ah,AH=4Eh,INT 2F/AX=111Bh

Format of DOS directory entry:
Offset	Size	Description	(Table 1217)
 00h  8 BYTEs	blank-padded filename
		first character is set to E5h for deleted files (05h for
		  pending delete files under Novell DOS / OpenDOS)
 08h  3 BYTEs	blank-padded file extension
 0Bh	BYTE	attributes
 0Ch 10 BYTEs	(MS-DOS 1.0-6.22) reserved
		(DR DOS) used to store file password / owner (see #1219)
			(see also INT 21/AX=4302h)
		(Novell DOS 7) DELWATCH data (see #1219)
		(MS-DOS 7/Windows95) additional file times (see #1218)
 16h	WORD	time of creation or last update (see #1530 at AX=5700h)
 18h	WORD	date of creation or last update (see #1531 at AX=5700h)
 1Ah	WORD	starting cluster number (see also AX=440Dh/CX=0871h)
		(not set for MSDOS 7.1 and FAT32-capable versions of Windows95)
 1Ch	DWORD	file size
SeeAlso: #1220,#2492,#2493

Format of MS-DOS 7/Windows95 additional file times:
Offset	Size	Description	(Table 1218)
 00h	BYTE	reserved
 01h	BYTE	10-millisecond units past creation time below
 02h	WORD	file creation time
 04h	WORD	file creation date
 06h	WORD	last-access date
 08h	WORD	(FAT32) high word of starting cluster number
Note:	this data is stored beginning at offset 0Ch in a standard directory
	  entry
SeeAlso: #1217

Format of DR DOS 6/Novell DOS 7 additional file information:
Offset	Size	Description	(Table 1219)
 0Ch	BYTE	reserved (00h)
 0Dh	BYTE	first character of original filename for deleted file
 0Eh	WORD	encrypted file/directory password
 10h	WORD	reserved (00h)
		(Novell DOS 7 DELWATCH) original file time
		    cleared when file is undeleted or purged
 12h	WORD	(DR DOS 6) file owner ID
		(Novell DOS 7 DELWATCH) original file date
		    cleared when file is undeleted or purged
 14h	WORD	single/multiuser file/directory access rights (see AX=4302h)
---deleted files---
 16h	WORD	(Novell DOS 7 DELWATCH) time of deletion
 18h	WORD	(Novell DOS 7 DELWATCH) date of deletion
Note:	offsets are within the full directory entry
SeeAlso: #1217

Format of MS-DOS 7/Windows95 long-filename directory entry:
Offset	Size	Description	(Table 1220)
 00h	BYTE	LFN record sequence and flags
		bits 5-0: sequence number
		bit 6: set if last long-filename record for file
		bit 7: set if file deleted
 01h 10 BYTEs	long filename, first part
 0Bh	BYTE	0Fh (otherwise impossible file attribute, used as signature)
 0Ch	BYTE	reserved??? (00h)
 0Dh	BYTE	checksum for short filename
 0Eh 12 BYTEs	long filename, second part
 1Ah	WORD	first cluster number (always 0000h for LFN records)
 1Ch  4 BYTEs	long filename, third part
Notes:	long-filename entries are always stored in the directory just prior
	  to the short-name entry for a file
	multiple LFN records are used if the long filename does not fit into
	  a single record
	the short-filename checksum byte is computed by adding up the
	  eleven bytes of the short filename, rotating the intermediate
	  sum right one bit before adding the next character
	the long filename is encoded as 16-bit Unicode characters; for most
	  filenames, this appears in the directory as the ASCII character
	  followed by 00h
SeeAlso: #1217,INT 21/AX=5704h,INT 21/AH=71h
--------D-2112-------------------------------
INT 21 - DOS 1+ - FIND NEXT MATCHING FILE USING FCB
	AH = 12h
	DS:DX -> unopened FCB (see #1210)
Return: AL = status
	    00h successful
		Disk Transfer Area filled with unopened FCB
	    FFh no more matching filenames
Note:	(see AH=11h)
	assumes that successful FindFirst executed on search FCB before call
SeeAlso: AH=1Ah,AH=4Fh,INT 2F/AX=111Ch
--------D-2113-------------------------------
INT 21 - DOS 1+ - DELETE FILE USING FCB
	AH = 13h
	DS:DX -> unopened FCB (see #1210), filename filled with template for
		deletion ('?' wildcards allowed)
Return: AL = status
	    00h one or more files successfully deleted
	    FFh no matching files or all were read-only or locked
Notes:	DOS 1.25+ deletes everything in the current directory (including
	  subdirectories) and sets the first byte of the name to 00h (entry
	  never used) instead of E5h if called on an extended FCB with
	  filename '???????????' and bits 0-4 of the attribute set (bits 1 and
	  2 for DOS 1.x).  This may have originally been an optimization to
	  minimize directory searching after a mass deletion (DOS 1.25+ stop
	  the directory search upon encountering a never-used entry), but can
	  corrupt the filesystem under DOS 2+ because subdirectories are
	  removed without deleting the files they contain.
	currently-open files should not be deleted
	MS-DOS allows deletion of read-only files with an extended FCB, whereas
	  Novell NetWare, DR DOS 6, and Novell DOS 7/OpenDOS 7.01 do not
	this function generates a trap "D" under OS/2 v4.x (Warp4) when called
	  on an HPFS partition with a wildcard in the filename; it operates
	  correctly on FAT partitions and when called without wildcards
SeeAlso: AH=41h,INT 2F/AX=1113h
--------D-2114-------------------------------
INT 21 - DOS 1+ - SEQUENTIAL READ FROM FCB FILE
	AH = 14h
	DS:DX -> opened FCB (see #1210)
Return: AL = status
	    00h successful
	    01h end of file (no data)
	    02h segment wrap in DTA
	    03h end of file, partial record read
	Disk Tranfer Area filled with record read from file
Notes:	reads a record of the size specified in the FCB beginning at the
	  current file position, then updates the current block and current
	  record fields in the FCB
	if a partial record was read, it is zero-padded to the full size
	not supported by MS Windows 3.0 DOSX.EXE DOS extender
SeeAlso: AH=0Fh,AH=15h,AH=1Ah,AH=3Fh"DOS",INT 2F/AX=1108h
--------D-2115-------------------------------
INT 21 - DOS 1+ - SEQUENTIAL WRITE TO FCB FILE
	AH = 15h
	DS:DX -> opened FCB (see #1210)
	Disk Tranfer Area contains record to be written
Return: AL = status
	    00h successful
	    01h disk full
	    02h segment wrap in DTA
Notes:	writes a record of the size specified in the FCB beginning at the
	  current file position, then updates the current block and current
	  record fields in the FCB
	if less than a full sector is written, the data is placed in a DOS
	  buffer to be written out at a later time
	not supported by MS Windows 3.0 DOSX.EXE DOS extender
SeeAlso: AH=0Fh,AH=14h,AH=1Ah,AH=40h,INT 2F/AX=1109h
--------D-2116-------------------------------
INT 21 - DOS 1+ - CREATE OR TRUNCATE FILE USING FCB
	AH = 16h
	DS:DX -> unopened FCB (see #1210), wildcards not allowed
Return: AL = status
	    00h successful
	    FFh directory full or file exists and is read-only or locked
Notes:	if file already exists, it is truncated to zero length
	if an extended FCB is used, the file is given the attribute in the
	  FCB; this is how to create a volume label in the disk's root dir
	not supported by MS Windows 3.0 DOSX.EXE DOS extender
	(FAT32 drive) this function will only succeed for creating a volume
	  label; FAT32 does not support FCBs for file I/O
SeeAlso: AH=0Fh,AH=10h,AH=3Ch
--------D-2117-------------------------------
INT 21 - DOS 1+ - RENAME FILE USING FCB
	AH = 17h
	DS:DX -> modified FCB (see also #1210)
		the old filename ('?' wildcards OK) is in the standard location
		while the new filename ('?' wildcards OK, no drive) is stored
		in the 11 bytes beginning at offset 11h
Return: AL = status
	    00h successfully renamed
	    FFh no matching files,file is read-only, or new name already exists
Notes:	subdirectories may be renamed using an extended FCB with the
	  appropriate attribute, as may volume labels
	DR DOS checks password attached with AX=4303h before permitting rename
SeeAlso: AH=0Fh,AH=13h,AX=4303h,AH=56h,INT 2F/AX=1111h
--------D-2118-------------------------------
INT 21 - DOS 1+ - NULL FUNCTION FOR CP/M COMPATIBILITY
	AH = 18h
Return: AL = 00h
Note:	corresponds to the CP/M BDOS function "get bit map of logged drives",
	  which is meaningless under MS-DOS
SeeAlso: AH=1Dh,AH=1Eh,AH=20h,AX=4459h,INT 60/DI=0513h
--------D-2119-------------------------------
INT 21 - DOS 1+ - GET CURRENT DEFAULT DRIVE
	AH = 19h
Return: AL = drive (00h = A:, 01h = B:, etc)
Note:	Novell NetWare uses the fact that DOS 2.x COMMAND.COM issues this call
	  from a particular location every time it starts a command to
	  determine when to issue an automatic EOJ
SeeAlso: AH=0Eh,AH=47h,AH=BBh
--------D-211A-------------------------------
INT 21 - DOS 1+ - SET DISK TRANSFER AREA ADDRESS
	AH = 1Ah
	DS:DX -> Disk Transfer Area (DTA)
Notes:	the DTA is set to PSP:0080h when a program is started
	under the FlashTek X-32 DOS extender, the pointer is in DS:EDX
SeeAlso: AH=11h,AH=12h,AH=2Fh,AH=4Eh,AH=4Fh
--------D-211B-------------------------------
INT 21 - DOS 1+ - GET ALLOCATION INFORMATION FOR DEFAULT DRIVE
	AH = 1Bh
Return: AL = sectors per cluster (allocation unit)
	CX = bytes per sector
	DX = total number of clusters
	DS:BX -> media ID byte (see #1221)
Notes:	under DOS 1.x, DS:BX points at an actual copy of the FAT; later
	  versions return a pointer to a copy of the FAT's ID byte
	this function may not be properly supported on CD-ROMs and other
	  installable file systems (use AX=4402h"CD-ROM" for CD-ROMs
	  instead)
SeeAlso: AH=1Ch,AH=36h

(Table 1221)
Values for media ID byte:
 FFh	floppy, double-sided, 8 sectors per track (320K)
 FEh	floppy, single-sided, 8 sectors per track (160K)
 FDh	floppy, double-sided, 9 sectors per track (360K)
 FCh	floppy, single-sided, 9 sectors per track (180K)
 FAh	HP 200LX D: ROM disk, 16 sectors per track (995K)
	HP 200LX E: (Stacker host drive ???)
 F9h	floppy, double-sided, 15 sectors per track (1.2M)
	floppy, double-sided, 9 sectors per track (720K,3.5")
 F8h	hard disk
 F0h	other media
	(e.g. floppy, double-sized, 18 sectors per track -- 1.44M,3.5")
--------D-211C-------------------------------
INT 21 - DOS 1+ - GET ALLOCATION INFORMATION FOR SPECIFIC DRIVE
	AH = 1Ch
	DL = drive (00h = default, 01h = A:, etc)
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 #1221)
Notes:	under DOS 1.x, DS:BX points at an actual copy of the FAT; later
	  versions return a pointer to a copy of the FAT's ID byte
	on a DBLSPACE drive, the total number of clusters is based on the
	  estimated compression ratio
	this function may not be properly supported on CD-ROMs and other
	  installable file systems (use AX=4402h"CD-ROM" for CD-ROMs
	  instead)
SeeAlso: AH=1Bh,AH=36h
--------D-211D-------------------------------
INT 21 - DOS 1+ - NULL FUNCTION FOR CP/M COMPATIBILITY
	AH = 1Dh
Return: AL = 00h
Note:	corresponds to the CP/M BDOS function "get bit map of read-only
	  drives", which is meaningless under MS-DOS
SeeAlso: AH=18h,AH=1Eh,AH=20h,AX=4459h
--------D-211E-------------------------------
INT 21 - DOS 1+ - NULL FUNCTION FOR CP/M COMPATIBILITY
	AH = 1Eh
Return: AL = 00h
Note:	corresponds to the CP/M BDOS function "set file attributes" which was
	 meaningless under MS-DOS 1.x
SeeAlso: AH=18h,AH=1Dh,AH=20h
--------D-211F-------------------------------
INT 21 - DOS 1+ - GET DRIVE PARAMETER BLOCK FOR DEFAULT DRIVE
	AH = 1Fh
Return: AL = status
	    00h successful
		DS:BX -> Drive Parameter Block (DPB) (see #1222 for DOS 1.x,
			AH=32h for DOS 2+)
	    FFh invalid drive
Note:	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
SeeAlso: AH=32h,AX=7302h

Format of DOS 1.1 and MS-DOS 1.25 drive parameter block:
Offset	Size	Description	(Table 1222)
 00h	BYTE	sequential device ID