1. The invention can avoid a check bit of indirect continual deleting the LDPC code.

2. Select proper drilling bit. Check bit for damage and to make sure it is sharp.

3. Check bit of divide operation circuits of RS codes is realized by using shift registers.

4. Parity bit: A check bit added to a series of binary digits to make the total odd or even according to the logic of the system.

5. Thi is an example of an even-parity format, but other computers use the check bit to produce an oll parity.

6. While the extended-Hamming code based on the Hamming code has 5 check bits by adding an additional 15th check bit.

7. The present invention also discloses one method of generating the optimal repeated output code from the input code and its check bit flow.