INT 31 P - DPMI 1.0+ - INSTALL RESIDENT HANDLER INIT CALLBACK AX = 0C00h ES:(E)DI -> resident service provider structure (see below) Return: CF clear if successful CF set on error AX = error code (8015h,8021h,8025h) (see AX=0000h) Note: calling this function declares an intent to provide resident protected mode services after terminating with AX=0C01h SeeAlso: AX=0303h,AX=0C01h Format of resident service provider structure: Offset Size Description 00h QWORD descriptor for 16-bit data segment 08h QWORD descriptor for 16-bit code segment (zeros if not supported) 10h WORD offset of 16-bit callback procedure 12h 2 BYTEs reserved 14h QWORD descriptor for 32-bit data segment 1Ch QWORD descriptor for 32-bit code segment (zeros if not supported) 24h DWORD offset of 32-bit callback procedure .