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310301

Category: DOS extenders
Flags: available only in protected mode

INT 31 - DPMI 0.9+ - CALL REAL MODE PROCEDURE WITH FAR RETURN FRAME

	AX = 0301h
	BH = flags
	    bit 0: reset the interrupt controller and A20 line (DPMI 0.9)
		    reserved, must be 0 (DPMI 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 at INT 31/AX=0300h)
Return: CF clear if successful
	    real mode call structure modified (all fields except SS:SP, CS:IP
	      filled with return values from real mode interrupt)
	CF set on error
	    AX = error code (DPMI 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
	the real mode procedure must exit with a FAR return
	DPMI 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=0300h,AX=0302h,AX=FF02h,INT 21/AX=250Eh,INT 21/AH=E1h"OS/286"
SeeAlso: INT 2C/AX=0025h

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  Copyright 2000   by Ralf Brown     Updated Jul 2000