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< EFM Test Iso >   by blackcheck 23.5.2002     
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Wanna play with weak sectors ? :P


What is this thing ?
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This little file will create a 640 MB iso containing
nothing but weak sectors.The iso includes all possible
16 bit repetitions.Each weak sector is repeated 5 times.
The Iso has no file system, so don't try to access it
with your windows explorer.



What should i do with it ?
-------------------------

Burn the iso with your favourite software and compare
it to the original file.I do not think there is ANY writer
that can write this file correctly.



How do weak sectors work ?
----------------------------------

Ask spath ;)

Here's what i know for sure:

According to ECMA-130 Annex B a regular bit pattern fed into 
the efm encoder can cause large digital sum values that cannot 
be reduced by the merging bits.To avoid this, sectors get scrambled 
before efm encoding.

A weak sector is an arrangement of bytes that when put through 
the scrambler forms a regular pattern.

If you scramble one of Safedisc2's weak sectors it looks like this:

D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 
D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 
D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 D9 04 



Big thanks to spath who translated the cryptic (at least for me) explanation 
in ECMA-130 Annex B to C.




Comments ?  black_check@yourass.com



