[Scummvm-devel] Fwd: from MAME forum

[Marcus Comstedt]

Max Horn <max at quendi.de> writes:

>  BTW, and slightly offtopic (the following is not meant pro
> nor contra the whole idea): Bits rarely flip on modern media. There
> are all kinds of damage that can occur, but bit flips on CDs or
> modern HDs are about as likely as being hit by a meteor (mind you I
> am not saying you can't loose data, but it'll manifest quite
> differently :-). Also I always wondered: Once you found out using MD5
> that "a bit flipped".... what exactly do you do then? :-)

If a bit flips on a CD, you'll never know about it.  The CD-ROM data
standard ("yellow book") includes an error correction code which is
able to automatically correct single bit and double bit errors.  If
three bits flip (in the same frame (24 bytes)), it can still be
detected, but not corrected.  In that case you'll get a read error
from the drive, not faulty data.


  // Marcus