Hamming Codes

• Calculate parity bits as follows:

P1= xor(3,5,7,9,11) = 1?1 ? 0 ? 0 ? 0 = 0

P2= xor(3,6,7,10,11) = 0

P4= xor(5,6,7,12) = 1

P8= xor(9,10,11,12) = 1

• When bits are read from memory, compute check bits:

C1= xor(1,3,5,7,9,11)

C2= xor(2,3,6,7,10,11)

C4= xor(4,5,6,7,12)

C8= xor(8,9,10,11,12)

1 2 3 4 5 6 7 8 9 10 11 12

0 0 1 1 1 0 0 1 0 1 0 0

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