Int 31 Fn EE20 - Dos32 V3.0+ - Get Real Mode Call Back Address With Retf [E]
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
See Also: AX=EE00h,AX=EE02h,AX=EE21h