IBM IC25N040ATCS04 - Travelstar 40 GB Hard Drive - 5.8 ECC

5.8 ECC
The 40 byte three interleaved ECC processor provides user data verification and correction capability. The
first 4 bytes of ECC are check bytes for user data and the other 36 bytes are Read Solomon ECC. Each
interleave has 12 bytes for ECC. Hardware logic corrects up to 15 bytes (5 bytes for each interleave)
errors on-the-fly.
Following are some examples of error cases. An "O" means that the byte contains no error. An "X" means
that at least one bit of the byte is bad.
On The Fly correctable
Byte # 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7
1 1 1 1 1 1 1 1
Interleave
A B C A B C A B C A B C A B C A B C
A B
C
Error pattern
5
Error byte # for
each interleave
X X X X X X X X X X X X X X X O O O
Error pattern
5
5
5
5 5
X X X X X X X X X O O O X X X X X X
Uncorrectable
Byte # 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7
1 1 1 1 1 1 1 1
Interleave
A B C A B C A B C A B C A B C A B C
A
B
C
Error pattern
6
Error byte # for
each interleave
X X X X X X X X X X X X X X X X O O
Error pattern
6
5
5
0 0
X O O X O O X O O X O O X O O X O O
Figure 16. Examples of error cases.
Travelstar 60GH & 40GN hard disk drive specifications
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