cactus data shield 200

[SafeDisk v2]

SAO-RAW:
Besides the standard RAW methods that are mentioned in the MMC standards we also have SAO-RAW. SAO in this case is not the same as Session At Once and therefore it is not an MMC standard!

Than what is SAO-RAW? SAO-RAW is nothing more than a software trick to get errors from the original disc onto the copy or back-up. This trick was first used by Wesson, creator of BlindSuite (www.blindwrite.com). Programs like DiscJuggler (www.padus.com) have used this method since the beginning to copy the 'unreadable' sectors. Unreadable does not mean that the writer cannot read the sectors, but it means the sectors are giving wrong (not compliant to the standards) information to it so that the writer will keep re-reading them and eventually will enter a "0" for these sectors.

If you want to back-up an error protected game like a game with the SafeDisc protection (which has about 10.000 error sectors in the first 5% of the disc) and the writer fills in a "0" for these sectors, the back-up will not work! The game has a build-in check to see if the error sectors are present and if they're not, it simply won't start and give a message like "Please insert the original CD"...

To prevent the writer of filling in a "0" for the error sectors a smart trick is used that works in the same way as an audio disc being written. To explain this we have to get a bit technical:

-A CD-R of 650MB has 333.000 sectors
-Each sector can hold a maximum of 2352 bytes

But here's the trick: a data sector can only hold 2048 bytes per sector! This is because a data sector will have space left for the error correction (so-called CRC-check). An audio sector does not use the CRC-check because audio is corrected by the hardware and therefore it can use the full 2352 bytes per sector!

SAO-RAW uses this to write 'data in an audio way' preventing the writer from doing an error correction and therefore it will write the errors on the back-up and thus producing a succesful copy.



Cheer's

[themis_t]

this was a good one safedisk!!!