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310302

Category: DOS extenders
Flags: available only in protected mode

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

	AX = 0302h
	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 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
	the real mode procedure must exit with an IRET
	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

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  Copyright 2000   by Ralf Brown     Updated Jul 2000