INT 67 - Virtual Control Program Interface - GET PROTECTED MODE INTERFACE
        AX = DE01h
        ES:DI -> 4K page table buffer
        DS:SI -> three descriptor table entries in GDT
                first becomes code segment descriptor, other two for use by
                main control program
Return: AH = 00h successful
            DI -> first unused page table entry in buffer
            EBX -> protected mode entry point in code segment
        AH = nonzero  failed
Note:   protected mode entry point may be called with AX=DE00h-DE05h and
          AX=DE0Ch (in each case, all other registers as appropriate for
          the function)
SeeAlso: INT 67/AH=3Fh

QEMM v6.03 protected mode entry point may also be called with:
        AX = DF00h ???
                ???
                Return: ???
        AX = DF01h ???
                ???
                Return: ???