Function 0400h returns the version of DPMI services supported. Note that this is not necessarily the version of any operating system that supports DPMI. It should be used by programs to determine what calls are legal in the current environment.
AX = 0400h
AH = Major version AL = Minor version BX = Flags Bit 0 = 1 if running under an 80386 DPMI implementation Bit 1 = 1 if processor is returned to real mode for reflected interrupts (as opposed to Virtual 8086 mode). Bit 2 = 1 if virtual memory is supported Bit 3 is reserved and undefined All other bits are zero and reserved for later use CL = Processor type 02 = 80286 03 = 80386 04 = 80486 DH = Current value of virtual master PIC base interrupt DL = Current value of virtual slave PIC base interrupt Carry flag clear (call can not fail)