PMODE/W duplicates a subset of DPMI protected mode functions.
These functions are available ONLY in protected through INT 31h.
They provide descriptor services, extended memory services,
interrupt services, translation services, and some other
miscellaneous things. A function is called by setting AX
to the function code, setting any other registers for the
function, and executing INT 31h. Upon return, the carry flag
will be clear if the function was successful. If the carry flag is set,
the function failed. All other registers are preserved unless otherwise
specified. In addition to the functions listed here,
functions 0600h, 0601h, 0702h, and 0703h will return
with the carry flag clear to stay compatible with code that uses those
particular DPMI functions.