INT 2F C - MS Windows - "V86MMGR" VIRTUAL DEVICE API(Application Program[ming] Interface) The defined set of calls which a program may make to interact with or request services of the operating system or environment under which it is running.  Because the inputs and outputs of the calls are well-defined, a program using the API can continue using the identical calls even if the internal organization of the program providing the API changes.
	AX = 1607h
	BX = 0006h (VxDA virtual device driver for Windows 3.x or 95.	So called because nearly all of the Windows 3.0 drivers had names of the form "VdeviceD". See also device driver. identifier of "V86MMGR")
	CX = 0000h
Return: AX = status
	    0000h if local A20(Address line 20) The 80286 and higher CPUs allow addresses in real mode to extend slightly beyond the one megabyte mark, which causes an incompatibility with some older programs which expect such addresses to wrap back to the beginning of the address space.  For complete compatibility with the 8088, newer machines thus contain circuitry which permits the twenty-first address line (A20) to be disabled.  The CPU then effectively has only twenty address lines in real mode, just as the 8088 does, and addresses which would extend beyond the one megabyte mark wrap to the beginning of the address space.  See also High Memory Area, Real Mode. state changed
	    1607h if A20(Address line 20) The 80286 and higher CPUs allow addresses in real mode to extend slightly beyond the one megabyte mark, which causes an incompatibility with some older programs which expect such addresses to wrap back to the beginning of the address space.  For complete compatibility with the 8088, newer machines thus contain circuitry which permits the twenty-first address line (A20) to be disabled.  The CPU then effectively has only twenty address lines in real mode, just as the 8088 does, and addresses which would extend beyond the one megabyte mark wrap to the beginning of the address space.  See also High Memory Area, Real Mode. unchanged
	    other if global A20(Address line 20) The 80286 and higher CPUs allow addresses in real mode to extend slightly beyond the one megabyte mark, which causes an incompatibility with some older programs which expect such addresses to wrap back to the beginning of the address space.  For complete compatibility with the 8088, newer machines thus contain circuitry which permits the twenty-first address line (A20) to be disabled.  The CPU then effectively has only twenty address lines in real mode, just as the 8088 does, and addresses which would extend beyond the one megabyte mark wrap to the beginning of the address space.  See also High Memory Area, Real Mode. state changed
SeeAlso: AX=1607h"CALL OUT API(Application Program[ming] Interface) The defined set of calls which a program may make to interact with or request services of the operating system or environment under which it is running.  Because the inputs and outputs of the calls are well-defined, a program using the API can continue using the identical calls even if the internal organization of the program providing the API changes."