[charlie_ps2]

I've come up with theories in the forum.

The one that is most likely is that Sony have put proprietary code into their Digital/Analogue section of the disk unit. What I think happens is that the Sony pressing kit introduces a wobble in the pre-groove area (which is outside the DVD-R spec).

The disk drive reads this area under special Sony firmware code and the photo diodes detect this wobble as a tracking error. Either the degree of tracking error is noted in the D/A section and/or it counts the sequencing and compares that via an algorithm with the appropriately encrypted region code.

When that test has been passed, the game can boot in the 'normal' way.

The Messiah does the first bit, feeding the appropriate PS2 registers with signals and data that correctly reports the pre-groove check OK. Then it activate the secnd part of the boot process to actually read the data part of the disk.