interrup.l

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

Interrupt List, part 12 of 18
Copyright (c) 1989-1999,2000 Ralf Brown
--------W-2F1600-----------------------------
INT 2F - MS Windows - WINDOWS ENHANCED MODE INSTALLATION CHECK
	AX = 1600h
Return: AL = status
	    00h neither Windows 3.x enhanced mode nor Windows/386 2.x running
	    01h Windows/386 2.x running
	    80h XMS version 1 driver installed (neither Windows 3.x enhanced
		  mode nor Windows/386 2.x running) (obsolete--see note)
	    FFh Windows/386 2.x running
	AL = anything else
	    AL = Windows major version number >= 3
	    AH = Windows minor version number
Notes:	INT 2F/AH=16h comprises an API for non-Windows programs (DOS device
	  drivers, TSRs, and applications) to cooperate with multitasking
	  Windows/386 2.x and Windows 3.x and higher enhanced mode.
	certain calls are also supported in the Microsoft 80286 DOS extender in
	  Windows standard mode
	this function served as the installation check and AX=1610h served to
	  get the driver entry point for XMS version 1, which is now obsolete.
	  Use AX=4300h and AX=4310h instead
	Windows95 reports version 4.00, Windows95B reports version 4.03
SeeAlso: AX=160Ah,AX=1610h,AX=4300h,AX=4680h
Index:	installation check;XMS version 1
--------W-2F1602-----------------------------
INT 2F - MS Windows/386 2.x - GET API ENTRY POINT
	AX = 1602h
Return: ES:DI -> Windows/386 2.x API procedure entry point
Notes:	this interface is supported in Windows 3.x and Windows95 only for 2.x
	  compatibility
	to get the current virtual machine (VM) ID in Windows/386 2.x:
	    AX = 0000h
	    ES:DI -> return address
	    JUMP to address returned from INT 2F/AX=1602h
	After JUMP, at return address:
	    BX = current VM ID.
SeeAlso: AX=C020h
--------W-2F1603-----------------------------
INT 2F C - MS Windows/386 - GET INSTANCE DATA
	AX = 1603h
Return: AX = 5248h ('RH') if supported
	    DS:SI -> Windows/386 instance data (see #02630)
Notes:	reportedly supported by RM Nimbus MS-DOS 3.3 kernel
	this function is called by DOSMGR when AX=1607h/BX=0015h is not
	  supported, as is the case in DOS versions prior to 5.0
	see Geoff Chappell's book _DOS_Internals_ for additional discussions of
	  this function, DOSMGR's behavior, and instancing in general
SeeAlso: AX=1607h/BX=0015h

Format of Windows/386 instance data:
Offset	Size	Description	(Table 02630)
 00h	WORD	segment of IO.SYS (0000h = default 0070h)
 02h	WORD	offset in IO.SYS of STACKS data structure (DOS 3.2x)
		0000h if not applicable
 04h	WORD	number of instance data entries (max 32)
 06h	Array of instance data entries
	Offset	Size	Description
	 00h	WORD	segment (0002h = DOS kernel)
	 02h	WORD	offset
	 04h	WORD	size
--------W-2F1605-----------------------------
INT 2F C - MS Windows - WINDOWS ENHANCED MODE & 286 DOSX INIT BROADCAST
	AX = 1605h
	ES:BX = 0000h:0000h
	DS:SI = 0000h:0000h
	CX = 0000h
	DX = flags
	    bit 0 = 0 if Windows enhanced-mode initialization
	    bit 0 = 1 if Microsoft 286 DOS extender initialization
	    bits 1-15 reserved (undefined)
	DI = version number (major in upper byte, minor in lower)
Return: CX = 0000h if okay for Windows to load
	CX = FFFFh (other registers unchanged) if Windows 3.0 in standard mode
	CX <> 0 if Windows should not load
	ES:BX -> startup info structure (see #02631)
	DS:SI -> virtual86 mode enable/disable callback or 0000h:0000h
	      (see #02634)
Notes:	the Windows enhanced mode loader and Microsoft 286 DOS extender will
	  broadcast an INT 2F/AX=1605h call when initializing.	Any DOS device
	  driver or TSR can watch for this broadcast and return the appropriate
	  values.  If the driver or TSR returns CX <> 0, it is also its
	  responsibility to display an error message (however, Windows95 is
	  reported to load regardless of the returned CX).
	each handler must first chain to the prior INT 2F handler with
	  registers unchanged before processing the call
	if the handler requires local data on a per-VM basis, it must store the
	  returned ES:BX in the "next" field of a startup info structure and
	  return a pointer to that structure in ES:BX
	a single TSR may set the V86 mode enable/disable callback; if DS:SI is
	  already nonzero, the TSR must fail the initialization by setting CX
	  nonzero
	MSD checks for Windows 3.0 running in standard mode by testing whether
	  CX=FFFFh and other registers are unchanged on return
	Novell DOS v7.0 (Update 8 - Update 11) TASKMGR in multitasking mode
	  uses this broadcast, even if TASKMGR.INI sets WinPresent= to OFF
	Microsoft's EMM386.EXE for DOS 5+ when installed with the NOEMS option
	  changes its driver name from EMMQXXX0 to EMMXXXX0 while Windows is
	  active
SeeAlso: AX=1606h,AX=1608h,AX=4B05h

Format of Windows Startup Information Structure:
Offset	Size	Description	(Table 02631)
 00h  2 BYTEs	major, minor version of info structure
 02h	DWORD	pointer to next startup info structure or 0000h:0000h
 06h	DWORD	pointer to ASCIZ name of virtual device file or 0000h:0000h
 0Ah	DWORD	virtual device reference data (see #02633)
		(only used if above nonzero)
 0Eh	DWORD	pointer to instance data records (see #02632) or 0000h:0000h
---structure version >= 4.0---
 12h	DWORD	pointer to optionally-instanced data records (see #02632)
		  or 0000h:0000h

Format of one Instance Item in array:
Offset	Size	Description	(Table 02632)
 00h	DWORD	address of instance data (end of array if 0000h:0000h)
 04h	WORD	size of instance data
SeeAlso: #02631

Format of Virtual Device Reference Data:
Offset	Size	Description	(Table 02633)
 00h	DWORD	physical address of ??? or 00000000h
 04h	DWORD	physical address of ??? table
 08h	DWORD	"DEST_PAGE" address to which pages must be mapped
 0Ch  N DWORDs	"SRC_PAGE" physical addresses of the pages
		00000000h = end of table
Note:	EMM386.EXE sets the first pointer to the start of the device driver
	  chain, the second pointer to a field of 40h bytes followed by a
	  16-bit offset to the end of the SRC_PAGE table, and DEST_PAGE to
	  the start segment of the UMB area
SeeAlso: #02631

(Table 02634)
Values Windows virtual mode enable/disable procedure is called with:
	AX = 0000h disable V86 mode
	AX = 0001h enable V86 mode
	interrupts disabled
Return: CF set on error
	CF clear if successful
	interrupts disabled
SeeAlso: #02631
--------W-2F1606-----------------------------
INT 2F C - MS Windows - WINDOWS ENHANCED MODE & 286 DOSX EXIT BROADCAST
	AX = 1606h
	DX = flags
	    bit 0 = 0 if Windows enhanced-mode exit
	    bit 0 = 1 if Microsoft 286 DOS extender exit
	    bits 1-15 reserved (undefined)
Notes:	if the init broadcast fails (AX=1605h returned CX <> 0), then this
	  broadcast will be issued immediately.
	this call will be issued in real mode
	Novell DOS v7.0 (Update 8 - Update 15) TASKMGR in multitasking mode
	  uses this broadcast, even if TASKMGR.INI sets WinPresent= to OFF
SeeAlso: AX=1605h,AX=1609h
--------W-2F1607-----------------------------
INT 2F C - MS Windows - VIRTUAL DEVICE CALL OUT API
	AX = 1607h
	BX = virtual device ID (see #02642)
	CX = (usually) callout subfunction
Return: (usually) AX,BX,CX,DX,ES contain results
Notes:	more of a convention than an API, this call specifies a standard
	  mechanism for Windows enhanced-mode virtual devices (VxD's) to talk
	  to DOS device drivers and TSRs
	see below for details on several virtual devices
SeeAlso: AX=1605h,AX=1607h/BX=000Ch,AX=1607h/BX=0014h,AX=1607h/BX=0015h
SeeAlso: AX=1607h/BX=0018h,AX=1684h"DEVICE API",AX=C020h
--------W-2F1607BX0006-----------------------
INT 2F C - MS Windows - "V86MMGR" VIRTUAL DEVICE API
	AX = 1607h
	BX = 0006h (VxD identifier of "V86MMGR")
	CX = 0000h
Return: AX = status
	    0000h if local A20 state changed
	    1607h if A20 unchanged
	    other if global A20 state changed
SeeAlso: AX=1607h"CALL OUT API"
--------W-2F1607BX000C-----------------------
INT 2F C - MS Windows - "VMD" VIRTUAL MOUSE DEVICE API
	AX = 1607h
	BX = 000Ch (VxD identifier of "VMD")
Return: CX = nonzero if mouse driver already virtualized
Note:	VMD (Virtual Mouse Driver) calls this and then checks whether CX is
	  nonzero; if yes, it will not automatically virtualize the mouse
	  driver.  This would be used if MOUSE.COM already virtualizes
	  itself using the Windows API.
SeeAlso: AX=1607h/BX=0014h,AX=1607h/BX=0015h
--------W-2F1607BX000D-----------------------
INT 2F C - MS Windows95 - "VKD" VIRTUAL DEVICE - ??? CALLOUT
	AX = 1607h
	BX = 000Dh (VxD ID for VKD)
	???
Return: ???
SeeAlso: AX=1607h"CALL OUT API",#02642
--------W-2F1607BX0010-----------------------
INT 2F C - MS Windows 3.1 - "BLOCKDEV" VIRTUAL HARD DISK DEVICE API
	AX = 1607h
	BX = 0010h (VxD identifier of "BLOCKDEV")
	CX = function
	    0001h starting FastDisk compatibility tests
	    0002h ending FastDisk compatibility tests
	    0003h check if FastDisk installation allowed
		Return: CX = 0000h if allowed
Note:	this interface is called by the Windows FastDisk driver (such as
	  WDCTRL) when it thinks that the INT 13h handler immediately below
	  IO.SYS's INT 13h code is not in ROM; it should be supported by any
	  program which hooks itself underneath IO.SYS's INT 13h code with
	  INT 2F/AH=13h
SeeAlso: AX=1607h/BX=0014h,INT 2F/AH=13h
--------W-2F1607BX0014-----------------------
INT 2F C - MS Windows - "VNETBIOS" VIRTUAL DEVICE API
	AX = 1607h
	BX = 0014h (VxD identifier of "VNETBIOS")
Return: ES:DI -> 128-byte table specifying VNETBIOS actions for each NetBIOS
		command code (see #02635)
Note:	VNETBIOS (Virtual NetBIOS) calls this function to determine whether
	  the NetBIOS has an extensions Windows should know about
SeeAlso: AX=1607h/BX=000Ch,AX=1607h/BX=0010h,AX=1607h/BX=0015h

(Table 02635)
Values for VNETBIOS action code:
 00h	"VN_Unknown" unknown command
 04h	"VN_No_Map"  no memory mapping necessary
 08h	"VN_Map_In"  input buffer is quickly used, so no global mapping needed
 0Ch	"VN_Map_In"  output buffer is quickly used, so no global mapping needed
 10h	"VN_Map_In_Out"	 buffer is quickly used, so no global mapping needed
 14h	"VN_Chain_Send"	 the chain-send command
 18h	"VN_Cancel"	special case for cancel command
 1Ch	"VN_Buffer_In"	buffer is incoming
 20h	"VN_Buffer_Out" buffer is outgoing
 24h	"VN_Buffer_In_Out" buffer used for both incoming and outgoing data
--------D-2F1607BX0015-----------------------
INT 2F C - MS Windows - "DOSMGR" VIRTUAL DEVICE API
	AX = 1607h
	BX = 0015h (VxD identifier of "DOSMGR")
	CX = function
	    0000h query instance processing
		DX = 0000h
		Return: CX = state
			    0000h not instanced
			    other instanced (DOS 5+ kernel returns 0001h)
				DX = segment of DOS drivers or 0000h for
					default of 0070h
				ES:BX -> patch table (see #02637)
	    0001h set patches in DOS
		DX = bit mask of patch requests (see #02636)
		Return: AX = B97Ch
			BX = bit mask of patches applied (see #02636)
			DX = A2ABh
	    0002h remove patches in DOS (ignored by DOS 5.0 kernel)
		DX = bit mask of patch requests (see #02636)
		Return: CX = 0000h (DOS 5-6)
		Note:	return values are ignored by DOSMGR in Windows 3.1
	    0003h get size of DOS data structures
		DX = bit mask of request (only one bit can be set)
		    bit 0: Current Directory Structure size
		Return: if supported request:
			    AX = B97Ch
			    CX = size in bytes of requested structure
			    DX = A2ABh
			else:
			    CX = 0000h
			    all other registers preserved
	    0004h determine instanced data structures
		Return: AX = B97Ch if supported
			DX = A2ABh if supported (DOS 5+ kernel returns 0000h)
			BX = bit mask of instanced items
			    bit 0: CDS
			    bit 1: SFT
			    bit 2: device list
			    bit 3: DOS swappable data area
	    0005h get device driver size
		ES = segment of device driver
		Return: DX:AX = 0000h:0000h on error (not dev. driver segment)
			DX:AX = A2ABh:B97Ch if successful
			    BX:CX = size of device driver in bytes
Notes:	DOSMGR (DOS Manager) will check whether the OEM DOS/BIOS data has
	  been instanced via this API and will not perform its own default
	  instancing of the normal DOS/BIOS data if so; if this API is not
	  supported, DOSMGR will also try to access instancing data through
	  INT 2F/AX=1603h
	these functions are supported by the DOS 5+ kernel; DOSMGR contains
	  tables of instancing information for earlier versions of DOS
	see Geoff Chappell's book _DOS_Internals_ for additional discussions of
	  DOSMGR's behavior and instancing in general
SeeAlso: AX=1603h,AX=1605h,AX=1607h/BX=000Ch,AX=1607h/BX=0014h
SeeAlso: AX=1684h"DEVICE API"

Bitfields for DOSMGR patch requests:
Bit(s)	Description	(Table 02636)
 0	enable critical sections
 1	NOP setting/checking user ID
 2	turn INT 21/AH=3Fh on STDIN into polling loop
 3	trap stack fault in "SYSINIT" to WIN386
 4	BIOS patch to trap "Insert disk X:" to WIN386

Format of DOSMGR patch table:
Offset	Size	Description	(Table 02637)
 00h  2 BYTEs	DOS version (major, minor)
 02h	WORD	offset in DOS data segment of "SAVEDS"
 04h	WORD	offset in DOS data segment of "SAVEBX"
 06h	WORD	offset in DOS data segment of InDOS flag
 08h	WORD	offset in DOS data segment of User ID word
 0Ah	WORD	offset in DOS data segment of "CritPatch" table to enable
		  critical section calls (see INT 2A/AH=80h)
 0Ch	WORD	(DOS 5+ only) offset in DOS data segment of "UMB_HEAD",
		  containing segment of last MCB in conventional memory
--------W-2F1607BX0018-----------------------
INT 2F C - MS Windows - "VMPoll" VIRTUAL DEVICE - IDLE CALLOUT
	AX = 1607h
	BX = 0018h (VMPoll VxD ID) (see #02642)
	CX = 0000h
Return: AX = status
	    0000h if timeslice used
	    nonzero if timeslice not needed
Note:	when VMPoll makes this callout, all virtual machines are idle, and any
	  interested TSR can use the opportunity to perform background
	  processing
SeeAlso: AX=1607h"CALL OUT API",AX=1689h
--------W-2F1607BX0021--------------------------------------
INT 2F C - MS Windows - "PageFile" VIRTUAL DEVICE - GET LOCK BYTE
	AX = 1607h
	BX = 0021h (PageFile VxD ID)
	CX = 0000h
Return: AX = status
	    0000h success
		ES:DI -> cache lock byte in disk cacher
	    other no disk cache or unsupported
Notes:	PageFile issues this call on real-mode initialization in order to allow
	  disk caches to provide it with a byte which it can use to temporarily
	  lock the disk cache; VMPOLL also issues this call, so it is made
	  twice each time Windows starts up
	if this call fails, PageFile falls back to other techniques for locking
	  the disk cache
SeeAlso: AX=1607h"CALL OUT API"
--------W-2F1607BX002D-----------------------
INT 2F C - MS Windows - "W32S" VIRTUAL DEVICE - ??? CALLOUT
	AX = 1607h
	BX = 002Dh (VxD ID for W32S)
	???
Return: ???
SeeAlso: AX=1607h"CALL OUT API",#02642
--------W-2F1607BX0040-----------------------