In order to use non-data bit patterns, disk drives use other kinds of encoding of the bit data, These encodings seem to waste space, but they are preferable to hard sectoring or other methods. One such bit encoding might use 00001111 to signal dead space and 00010001 to signal that the next group of bits begins the sector. Then the actual bits are encoded using 10 for 0, and 01 for 1. Thus, 'A' would be encoded as 1001101010101001. This halves the raw bit capacity of the disk drive, but for many reasons this sacrifice is worthwhile.