We have improved the accuracy of the operation timing of the PIT.
CPUBENCH, etc., I think whether a result of the variation has decreased.
int 21h, ah = 44h (IOCTRL relationship) and int 21h, now supports the ax = 71aah (SUBST).
SUBST looks like move, but ... too much meaning is not I guess (laughs)
It gave a code cleanups for debugging.
As a result found, so far it has been some implement the service was not implemented.
However, the majority is simply the function returns an error of that it is not supported.