Int 2F Fn 1219  U - DOS 3+ Internal - Set Drive???                         [D]

   AX = 1219h
   SS = DOS DS (must be using a DOS internal stack)
   STACK: WORD drive (0 = default, 1 = A:, etc)

Return: ???
   STACK unchanged

Notes: calls AX=1217h
   builds a current directory structure if inside server call
     (INT 21/AX=5D00h)

See Also: AX=1217h,AX=121Fh