INT 31 P - DPMIsee DOS Protected-Mode Interface 0.9+ - SIMULATE REAL MODE INTERRUPT
	AX = 0300h
	BL = interrupt number
	BH = flags
	    bit 0: reset the interrupt controller and 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. line (DPMIsee DOS Protected-Mode Interface 0.9)
		    reserved, must be 0 (DPMIsee DOS Protected-Mode Interface 1.0+)
	    others: reserved, must be 0
	CX = number of words to copy from protected mode to real mode stack
	ES:(E)DI = selector:offset of real mode call structure (see #03148)
Return: CF clear if successful
	    real mode call structure modified (all fields except SS:SP, CS:IP(Internet Protocol) The lower level (transport layer) of the TCP/IP protocol suite.	See also TCP, TCP/IP.
	      filled with return values from real mode interrupt)
	CF set on error
	    AX = error code (DPMIsee DOS Protected-Mode Interface 1.0+) (8012h,8013h,8014h,8021h)(see #03143)
	protected mode stack unchanged
Notes:	16-bit programs use ES:DI as pointer, 32-bit programs use ES:EDI
	CS:IP(Internet Protocol) The lower level (transport layer) of the TCP/IP protocol suite.	See also TCP, TCP/IP. in the real mode call structure is ignored for this call,
	  instead, the indicated interrupt vector is used for the address
	the flags in the call structure are pushed on the real mode stack to
	  form an interrupt stack frame, and the trace and interrupt flags are
	  clear on entry to the handler
	DPMIsee DOS Protected-Mode Interface will provide a small (30 words) real mode stack if SS:SP is zero
	the real mode handler must return with the stack in the same state as
	  it was on being called
SeeAlso: AX=0302h,AX=FF01h,INT 21/AX=2511h,INT 21/AH=E3h"OS/286"
SeeAlso: INT 2C/AX=0026h,INT 2F/AX=FB42h/BX=000Dh


Format of DPMIsee DOS Protected-Mode Interface real mode call structure:
Offset	Size	Description	(Table 03148)
 00h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	EDI
 04h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	ESI
 08h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	EBP
 0Ch	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	reserved (00h)
 10h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	EBX
 14h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	EDX
 18h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	ECX
 1Ch	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	EAX
 20h	WORD	flags
 22h	WORD	ES
 24h	WORD	DS
 26h	WORD	FS
 28h	WORD	GS
 2Ah	WORD	IP(Internet Protocol) The lower level (transport layer) of the TCP/IP protocol suite.	See also TCP, TCP/IP.
 2Ch	WORD	CS
 2Eh	WORD	SP
 30h	WORD	SS