interrup.k

A Programmer s Reference to BIOS, DOS, and Third-Party Calls

Interrupt List, part 11 of 18
Copyright (c) 1989-1999,2000 Ralf Brown
--------D-26---------------------------------
INT 26 - DOS 1+ - ABSOLUTE DISK WRITE (except partitions > 32M)
	AL = drive number (00h = A:, 01h = B:, etc)
	CX = number of sectors to write (not FFFFh)
	DX = starting logical sector number (0000h - highest sector on drive)
	DS:BX -> data to write
Return: CF clear if successful
	CF set on error
	    AH = status (see #02547)
	    AL = error code (same as passed to INT 24 in DI)
	    AX = 0207h if more than 64K sectors on drive -- use new-style call
	may destroy all other registers except segment registers
Notes:	original flags are left on stack, and must be popped by caller
	this call bypasses the DOS filesystem, though DOS 5+ invalidates any
	  disk buffers referencing sectors which are written with this call
	examination of CPWIN386.CPL indicates that if this call fails with
	  error 0408h on an old-style (<32M) call, one should retry the
	  call with the high bit of the drive number in AL set
	Novell DOS 7 decides whether the old-style or new-style (>32M) version
	  of INT 26 must be used solely on the basis of the partition's size,
	  thus forcing use of the new-style call even for data in the first
	  32M of the partition
	Windows98 will display an error message and deliberately hang the
	  system on attempted write to any hard disk if neither bit 7 of the
	  Extended Drive Info byte nor bit 6 of "DOS_FLAG" (List-of-Lists+60h)
	  is set
	Although all registers except segment registers may be destroyed
	 some software depends on some of the registers being preserved.
	 For example some Flash disk drivers requires that DX is not trashed.
	 DR-DOS 7.03 takes care of this.
BUGS:	DOS 3.1 through 3.3 set the word at ES:[BP+1Eh] to FFFFh if AL is an
	  invalid drive number
	DR DOS 3.41 will return with a jump instead of RETF, leaving the
	  wrong number of bytes on the stack; use the huge-partition version
	  (INT 26/CX=FFFFh) for all partition sizes under DR DOS 3.41
	DR DOS 6.0 original releases 05/1991 & 08/1991 reported wrong error
	  codes for "drive not ready" and "write protect". This was fixed
	  with the DR DOS BDOS patch "PAT321" (1992/02/19, XDIR /C: 947Bh)
	  and later "full" rebuilds (see INT21/AX=4452h for details).
SeeAlso: INT 13/AH=03h,INT 25,INT 26/CX=FFFFh,INT 21/AX=7305h,INT 21/AH=91h"PTS"
--------D-26----CXFFFF-----------------------
INT 26 - DOS 3.31+ - ABSOLUTE DISK WRITE (32M-2047M hard-disk partition)
	CX = FFFFh
	AL = drive number (0=A, 1=B, etc)
	DS:BX -> disk write packet (see #02552)
Return: CF clear if successful
	CF set on error
	    AH = status (see #02547)
	    AL = error code (same as passed to INT 24 in DI)
	may destroy all other registers except segment registers
Notes:	partition is potentially >32M (and requires this form of the call) if
	  bit 1 of the device attribute word in the device driver is set
	original flags are left on stack, and must be removed by caller
	this call bypasses the DOS filesystem, though DOS 5+ invalidates any
	  disk buffers referencing sectors which are written with this call
	for FAT32 drives (which may be up to 2TB in size), use INT 21/AX=7305h
	Windows98 will display an error message and deliberately hang the
	  system on attempted write to any hard disk if neither bit 7 of the
	  Extended Drive Info byte nor bit 6 of "DOS_FLAG" (List-of-Lists+60h)
	  is set
SeeAlso: INT 13/AH=03h,INT 25/CX=FFFFh,INT 26,INT 21/AX=7305h

Format of disk write packet:
Offset	Size	Description	(Table 02552)
 00h	DWORD	sector number
 04h	WORD	number of sectors to read
 06h	DWORD	transfer address
SeeAlso: #02548
--------G-26---------------------------------
INT 26 - COMTROL HOSTESS i/ISA DEBUGGER - ENTER/EXIT EXTENDED ADDRESSING MODE
	???
Return: ???
SeeAlso: INT 23"COMTROL",INT 27"COMTROL"
--------D-27---------------------------------
INT 27 - DOS 1+ - TERMINATE AND STAY RESIDENT
	DX = number of bytes to keep resident (max FFF0h)
	CS = segment of PSP
Return: never
Notes:	this is an obsolete call
	INT 22, INT 23, and INT 24 are restored from the PSP
	does not close any open files
	the minimum number of bytes which will remain resident is 110h for
	  DOS 2.x and 60h for DOS 3.0+; there is no minimum for DOS 1.x, which
	  implements this service in COMMAND.COM rather than the DOS kernel
SeeAlso: INT 21/AH=31h
--------G-27---------------------------------
INT 27 - COMTROL HOSTESS i/ISA DEBUGGER - INVOKE REMOTE TURBO DEBUGGER KERNEL
	???
Return: ???
Desc:	invoke a copy of the remote Turbo Debugger kernel on the Hostess i
	  controller
SeeAlso: INT 20"COMTROL",INT 26"COMTROL"
--------D-28---------------------------------
INT 28 C - DOS 2+ - DOS IDLE INTERRUPT
	SS:SP = top of MS-DOS stack for I/O functions
Return: all registers preserved
Desc:	This interrupt is invoked each time one of the DOS character input
	  functions loops while waiting for input.  Since a DOS call is in
	  progress even though DOS is actually idle during such input waits,
	  hooking this function is necessary to allow a TSR to perform DOS
	  calls while the foreground program is waiting for user input.	 The
	  INT 28h handler may invoke any INT 21h function except functions
	  00h through 0Ch.
Notes:	under DOS 2.x, the critical error flag (the byte immediately after the
	  InDOS flag) must be set in order to call DOS functions 50h/51h from
	  the INT 28h handler without destroying the DOS stacks.
	calls to INT 21/AH=3Fh,40h from within an INT 28 handler may not use a
	  handle which refers to CON
	at the time of the call, the InDOS flag (see INT 21/AH=34h) is normally
	  set to 01h; if larger, DOS is truly busy and should not be reentered
	the default handler is an IRET instruction
	supported in OS/2 compatibility box
	the _MS-DOS_Programmer's_Reference_ for DOS 5.0 incorrectly documents
	  this interrupt as superseded
	the performance of NetWare Lite servers (and probably other peer-to-
	  peer networks) can be dramatically improved by calling INT 28
	  frequently from an application's idle loop
SeeAlso: INT 21/AH=34h,INT 2A/AH=84h,INT 2F/AX=1680h
--------U-289999-----------------------------
INT 28 u - PCXDUMP v9.00+ - INSTALLATION CHECK
	AX = 9999h
Return: AX = AAAAh if installed
	    CX = version number * 100 (example: 03A2h = 930 = v9.30)
	    DL = interrupt used by the dump function (see #02553)
		(00h if call not available)
	    BX = CS of PCXDUMP's INT 28 handler (undocumented)
	    ES = segment of PCXDUMP's memory block (v9.30, undocumented)
Program: PCXDUMP is a shareware screen grabber saving in PCX format
Notes:	if DL<>00h a dump can be requested by calling INT DL as shown
	  below (the user can choose the interrupt number at installation
	  time); if DL=00h the dump function can be called only by hotkeys
	  (this is the default)

(Table 02553)
Call PCXDUMP screen-dump function with:
	INT xx
	AX = 1234h
	BX = dump type
	    0000h Color dump
	    0001h Immediate color dump
	    0002h Black/White dump
	    0003h Immediate B/W dump
	    0004h Inverted B/W dump
	    0005h Gray scaled dump
	    0006h Inverted gray scaled dump
	    0007h Text screen dump to text file
	    0008h Text screen dump to ansi file
Return: nothing
Notes:	if BX=0001h, 0003h, 0007h or 0008h the whole screen will be
	  dumped; the other valid values will draw a selection frame
	  on the screen except in text modes (text modes allow only
	  full screen dumps)
	this function doesn't perform the dump, it only requests it;
	  the dump will be performed after a few milliseconds if it's
	  safe to do so, thus the author recommends putting a 60 ms delay
	  after this call
--------D-29---------------------------------
INT 29 C - DOS 2+ - FAST CONSOLE OUTPUT
	AL = character to display
Return: nothing
	BX may be destroyed by some versions of DOS 3.3
Notes:	automatically called when writing to a device with bit 4 of its device
	  driver header set (see also INT 21/AH=52h)
	COMMAND.COM v3.2 and v3.3 compare the INT 29 vector against the INT 20
	  vector and assume that ANSI.SYS is installed if the segment is larger
	the default handler under DOS 2.x and 3.x simply calls INT 10/AH=0Eh
	the default handler under DESQview 2.2 understands the <Esc>[2J
	  screen-clearing sequence, calls INT 10/AH=0Eh for all others
SeeAlso: INT 21/AH=52h,INT 2F/AX=0802h,INT 79"AVATAR.SYS"
--------U-29E60DCL0E-------------------------
INT 29 - ShowGFX - INSTALLATION CHECK
	AX = E60Dh
	CL = 0Eh
	DX = C0DEh
Return: DX = DEC0h
Program: ShowGFX is a PCBoard graphics driver by Solar Designer
--------N-2A00-------------------------------
INT 2A - NETWORK - INSTALLATION CHECK
	AH = 00h
Return: AH <> 00h if installed
	CF set if NetWare v2.15 NetBIOS emulator installed
Note:	supported by PC LAN Program, LAN Manager, LANtastic, NetWare, 10NET,
	  etc.
SeeAlso: INT 5C"NetBIOS"
--------N-2A0000-----------------------------
INT 2A - AT&T Starlan Extended NetBIOS (var length names) - INSTALLATION CHECK
	AX = 0000h
Return: AH = DDh
SeeAlso: INT 5B"Extended NetBIOS"
--------N-2A01-------------------------------
INT 2A - NETWORK (Microsoft,LANtastic) - EXECUTE NETBIOS REQUEST,NO ERROR RETRY
	AH = 01h
	ES:BX -> NCB (see #03249 at INT 5C"NetBIOS")
Return: AL = NetBIOS error code
	AH = status
	    00h no error
	    01h error occurred
SeeAlso: AH=04h,AX=0500h,INT 5B"Extended NetBIOS",INT 5C"NetBIOS"
--------N-2A02-------------------------------
INT 2A - NETWORK (Microsoft) - SET NET PRINTER MODE
	AH = 02h
	???
Return: ???
--------N-2A0300-----------------------------
INT 2A - NETWORK - CHECK DIRECT I/O
	AX = 0300h
	DS:SI -> ASCIZ device name (may be full path or only drive specifier--
		  must include the colon)
Return: CF clear if direct physical addressing (INT 13,INT 25) permissible
	CF set if access via files only
Notes:	do not use direct disk accesses if this function returns CF set or the
	  device is redirected (INT 21/AX=5F02h)
	use AH=00h to determine whether the network is installed; if not,
	  direct physical access is allowed
	may take some time to execute, so programs which need to check
	  frequently should save the result of the first call
	this function is called by the DOS kernel on INT 25 and INT 26
	supported by PC LAN Program, LAN Manage, LANtastic, NetWare, 10NET,
	  etc.
SeeAlso: INT 13/AH=02h,INT 13/AH=03h,INT 25,INT 26,INT 21/AX=5F02h
--------N-2A04-------------------------------
INT 2A - NETWORK - EXECUTE NetBIOS REQUEST
	AH = 04h
	AL = error retry
	    00h automatically retry request on errors 09h, 12h, and 21h
		  (see #03248 at INT 5C"NetBIOS")
	    01h no retry
	    02h ???
	ES:BX -> Network Control Block (see #03249 at INT 5C"NetBIOS")
Return: AX = 0000h if successful
	AH = 01h on error
	    AL = error code
Notes:	invokes either INT 5B or INT 5C as appropriate
	supported by PC LAN Program, LANtastic, LAN Manager, NetWare, 10NET,
	  etc.
	NetWare 2.15 NetBIOS emulator returns CF clear if successful, CF set
	  on error
	PC LAN Program defines any non-zero return value in AH as an error
	  indicator for subfunction 00h, and any non-zero return value in AX
	  as an error indicator for subfunction 01h
SeeAlso: AH=00h,AH=01h,AX=0500h,INT 5B"Extended NetBIOS",INT 5C"NetBIOS"
--------N-2A0500-----------------------------
INT 2A - NETWORK - GET NETWORK RESOURCE AVAILABILITY
	AX = 0500h
Return: AX reserved
	BX = number of network names available
	CX = number of network control blocks available
	DX = number of network sessions available
Notes:	supported by PC LAN Program, LAN Manager, LANtastic, NetWare, 10NET,
	  etc.
	the application should call this function before using any network
	  resources, and maintain its own count to avoid exceeding the
	  network's resource limits
SeeAlso: AH=00h,AH=01h,AH=04h,INT 5C"NetBIOS"
--------N-2A06-------------------------------
INT 2A - NETBIOS, LANtastic - NETWORK PRINT-STREAM CONTROL
	AH = 06h
	AL = function
	    01h set concatenation mode
		all printer output put in one job until return to DOS prompt
	    02h set truncation mode (default)
		printer open/close or BIOS/DOS output switch starts new job
	    03h flush printer output and start new print job
Return: CF set on error
	    AX = error code
	CF clear if successful
Notes:	subfunction 03h is equivalent to Ctrl/Alt/keypad-*
	supported by PC LAN Program, LANtastic, NetWare, 10NET, etc.
	LANtastic v4.x no longer supports this call
	this function sets the printer mode for all redirected printers
SeeAlso: INT 21/AX=5D08h,INT 21/AX=5D09h,INT 2F/AX=1125h
--------N-2A07-------------------------------
INT 2A U - PC Network v1.00 - RECEIVER.COM - ???
	AH = 07h
	???
Return: ???
Program: PC Network is an early networking package which was renamed the
	  IBM PC Local Area Network Program (PC LAN Program) as of v1.10
SeeAlso: AH=86h
--------N-2A2001-----------------------------
INT 2A - MS Networks or NETBIOS - ???
	AX = 2001h
	???
Return: ???
Note:	intercepted by DESQview 2.x
--------N-2A2002-----------------------------
INT 2A - NETWORK - ???
	AX = 2002h
	???
Return: ???
Note:	called by MS-DOS 3.30-6.00 APPEND
--------N-2A2003-----------------------------
INT 2A - NETWORK - ???
	AX = 2003h
	???
Return: ???
Note:	called by MS-DOS 3.30-6.00 APPEND
--------N-2A4147DX0000-----------------------
INT 2A U - NetSoft DOS-NET v1.20+ - INSTALLATION CHECK
	AX = 4147h ('AG')
	DX = 0000h
Return: DX = 4147h if installed
	    DS:SI -> configuration data (see #02554)
Program: DOS-NET is a shareware networking package by Albert Graham
Note:	this call is supported by CLIENT.COM, SERVER.COM, ROUTER.COM, and
	  NETDOS.COM
SeeAlso: INT 65/DX=4147h,INT 65/DX=4741h

Format of DOS-NET v1.20 configuration data area:
Offset	Size	Description	(Table 02554)
 00h	BYTE	???
 01h	BYTE	interrupt number used by DOS-NET APIs
 02h	WORD	function number to place in AX for above interrupt
 04h	BYTE	minor version as two BCD digits (e.g. 20h for v1.20)
 05h	BYTE	major version number (01h for v1.20)
 06h  2 BYTEs	???