INT 31 P - DPMI 1.0+ - MAP CONVENTIONAL MEMORY IN MEMORY BLOCK
        AX = 0509h
        ESI = memory block handle
        EBX = page-aligned offset within memory block of page(s) to map
        ECX = number of pages to map
        EDX = page-aligned linear address of conventional (below 1M) memory
Return: CF clear if successful
        CF set on error
            AX = error code (8001h,8003h,8023h,8025h) (see AX=0000h)
Notes:  only supported by 32-bit DPMI hosts, but may be used by 16-bit clients
        support of this function is optional
SeeAlso: AX=0508h,AX=0801h