Returns the current directory of a specified drive.
procedure GetDir(D: Byte; var S: String);
where D is set to:
1 Drive A
2 Drive B
3 Drive C
Windows, Real, Protected
Performs no error checking. If the drive specified by D is invalid, S returns X:\ as if it were the root directory of the invalid drive.
performs the same function as GetDir but it takes a null-terminated string as an argument instead of a Pascal-style string.