Interesting read, but a total fabrication.
DSV exists and you do need to keep the DSV sum close to zero when encoding EFM. But Iâ€™m afraid it has nothing to do with the protection on PS2 media.
Also, the erroneous data on our discs is nothing to do with the PS2 disc protection. It does make our discs unreadable in a PC (or at least certain data sectors), but it came about mainly because I didnâ€™t get round to encoding those sectors as I didnâ€™t need them; Plus we liked the side effect of the disc being hard to read in a PC. Funny enough, when the PSX came out in Japan, I had to fix a whole range of sectors as our disc didnâ€™t work in it. If you compare one of out early Jap discs to a newer one, you will find a PC will not even recognize the early disc, but put with a newer disc in a PC and you get a file list.
In answer to â€œSo why cant Datel press discs like Sonyâ€: We can and we do, but we only make our own products.
The reason all the discs are the same (all Japanse discs, all Europe discs, all USA discs) is because I use the same protection key on the disc. I could quite easily use a different key, but why bother?
Fortunately, the PS2 is nowhere near dead and hence I canâ€™t disclose exactly how the PS2 protection works. The PS2 has at least another 2 years left in it from a software & peripherals manufacturer point of view, just look at how long and well the PSOne sold after the PS2 came out!
I can tell you I wrote a lot of software including data analysis and full decoders & encoders for CD HF and EFM. Far too much time was spent with microscopes, expensive CD test hardware, oscilloscopes, digital and analogue samplers. PS2 guts decorated my desk along with empty Dr Pepper cans. It took a number of late nights over a period of about 10 months from start to finish. And it helped to have a mastering plant!