[lucb1e]

> That copy protection scheme (outer ring spiral) is quite something.

Yeah about that, I don't get it. Is there data hidden in that spiral that acts as a checksum for the CD or something? Or is it of special material that lights up differently under certain light (like money)?

To me it doesn't look that hard to duplicate a simple spiral, but then I know nothing about it.

[christoph]

Consumer CD writers and CD-R's don't have the ability to write anything similar to the disc.

Gamecube discs utilised a similar technology which you can easily see on the disc surface - http://www.gamesx.com/grafx/ngcdisc2.jpg & https://en.wikipedia.org/wiki/Nintendo_optical_discs#Burst_c...

Years before, companies actually did a similar thing with floppy discs, albeit in a slightly different way.

https://en.wikipedia.org/wiki/Bad_sector

[rasz_pl]

original Playstation used similar copy protection trick - ASCII string SCE(I/E/A) was stored in pregap pre-groove wobble between the leadin and the first track. PSX used Three-beam pickup and was able to track this wobble and extract code from radial tracking error signals. Modchips simply injected same error signal for couple of seconds after closing CD lid, enough for the CD controller to recognize it as "original".

[voltagex_]

Any idea why PS modchips used to kill the drive laser pretty quickly?

[rasz_pl]

they didnt. lasers were poor to begin with, plus weaker media(cdr) probably caused extra mechanism movements (focusing)

edit: hmm, now that I think about it, its possible someone incompetent made modchip that would keep sending wooble constantly, that could cause tracking problems and tire mechanism pretty fast.