Int 2F Fn 120E  U - Dos 3.0+ Internal - Mark All Disk Buffers Unreference  [D]

   AX = 120Eh
   SS = DOS DS (must be using a DOS internal stack)

Return: DS:DI -> first disk buffer

Notes: clears "referenced" flag on all disk buffers
   in DOS 5+, this has become essentially a NOP, invoking the same code
     used by AX=1224h (SHARING DELAY)

See Also: AX=1209h,AX=1210h,INT 21/AH=0Dh