INT 31 - DOS32 v3.0+ - GET REAL MODE CALL BACK ADDRESS WITH RETF STACK FRAME
AX = EE20h
ESI = offset of the real mode call back function
Return: CF clear if successful
CX:DX = real mode address to call up to the protected mode
procedure
CF set on error
SeeAlso: AX=EE00h,AX=EE02h,AX=EE21h