0040h:0080h           Keyboard Buffer Start Offset Pointer

    Length: 2 bytes

    This word contains the offset of the start of the keyboard buffer.
    This allows you to move the buffer, increase its size, or decrease
    its size. There is one catch, however: The address here is an
    offset starting at address 0040h:0000h. For example, the default
    32-byte buffer at 0040h:001Eh forces this offset address to be
    001Eh. Therefore, if the buffer is to be moved to another
    location, the buffer starting offset must be relative to
    0040h:0000h.