Sega Saturn cp talk

[themabus]

the thing is, i have saturn only for about half of the year and never tried to rund non Japanese CDs,
but i think you're right. probably it would act different from copy.

Vigi, ok, i'll check you'r sector.
i tried to burn your image yesterday as an audio cd on 650mb rw, so that ther's no need for scrambling.
but nothing is visible, not even change from erroneous zone with $55s to ring. i guess contrast is too low, after all.
edit:
oh, ok i did
yes, those bytes, i think they are from previous sector. it's not different from how rest cd is made and so we get
sector with some offset, instead of requested one. but from your cd it looks different, form data track.
it's 222 in db, but here difference is several sectors, i'll have to check my cd's on this again.
so meanwhile i've uploaded you'r MK2 image (from yesterday) here:
http://www.mediafire.com/?81ynydnbmd1



also from image with data block x2000, i'm now almost sure it's sync up there. i belive, little lower,
it's 4 parity bytes, then 12 bytes forming block, 4 parity again...
but ther's no sync formed arrays on data track, so i guess they've manipulated with speed/pit lenght @ring.
i guess it means trying to get visible logo, it's useless - it's not going to happen.
but i think it should be possible to get ring with software, so we would know at least it's properties
and maybe we could synthesize it later on (if sector content does not matter, maybe it's possible?).
...but i'm not even sure, it's logo, that matters, i think that's what RPS said. and he said it's not possible to reproduce
but it's at least interesting to understand 'how?'.

also i got those saturn CDs and will try to check ranges again on d8.

[themabus]

Vigi, you were right about offset difference on sega logo.
from 6 cds i've checked 4 offsets match with datatrack offset but 2 doesn't.

i've checked ranges and all those rings do end there (4 at the same place, @LBA 328124), right on sector boundary.
then follow some zero sectors, while subchannel is still readable, but soon it runs out.

those zones with background $59 @the start and the end of ring,
i think, they work like a buffer. some cd's have them smaller, some larger - it doe's not matter.

about your Mortak Kombat image: i think, most likely, it does not matter about how sectors are alignet.
laser would seek 297700 (66:11:25) in subchannel and correct itself to locate right sector.
also i think, this change, it does not affect logo pattern (since unit is sector). so, it could be both ways.

[Jackal]

With offset difference you mean that MK2 has +222 before ring and +150 (180-30) after?

Anyway, I was thinking.. maybe there are actually some readable sectors inside the ring? is there any way we could check this accurately? (ddump resets the drive after every sector read, I'm not sure if this makes any difference or if other tools do this as well?)

[themabus]

i call that logo zone 'ring'
i mean when you check that zone for offset, like you do on data tracks, this offset, it sometimes differ from the rest of cd.
like in your Mortal Kombat. it's +222 for data - ok, but i think it should be higher, for ring, because that sector, you uploaded,
it's MSF:66:11:19 (297694), so difference with requested sector 66:11:25 (297700) is 6 sectors and 180 samples
(those preceding 1st sector with header in your dump), but maybe i'm wrong here

about data in this area, i don't think there is any. on microscope photo it's empty, so there cant be full (round) 'track'.
i've found boundaries of this transition zone between data->logo with Truman's 'cdreader' on the same cd, i did microscope readings.
it's exactly 1350 wide. from photos i'd guess it's about 31~32 tracks in there, so 1350/31=~43 sectors per track.
so there is no 43 continuous sectors in there.
when i looked for zone boundaries earlier today, it's quite hard to get there. if you go from e.g. 300000 to 320000
and data ends @328000, laser can often skip past data and will loose track. and it's thousands of sectors.
so i don't think laser would be able to find anything there. though maybe there could be some pattern, that's not read as data at all.
so that would mean Saturn is way different, but on PC i think it's impossible to verify. i think Cdrwin did reading for very long, until
it get past this area, but i would not trust, if it returns anything. probably junk.
it would show on microscope tho

also i've run logo sectors data through circ delay lines simulation, and looked for a best contrast by statistics.
(and it's a bit strange actually, it wasn't per sample unit)
i did this before, but now i realigned data in tracks, looking for patterns.
and this is what i got:




it's first and last characters of each sentance, later those patterns run onto eachother and become unreadable.
i guess - maybe my circ is wrong. or could be holographic image is made this way? - i would not know.

[themabus]

there was an error in circ
i'll post logo details tomorrow

[Jackal]

1337 paint skillz keep it coming

Vigi, you were right about offset difference on sega logo.
from 6 cds i've checked 4 offsets match with datatrack offset but 2 doesn't.

You were right about the 6 sectors, so I guess the write offset after the ring is 6x588 + (180-30) = +3678 vs +222 before (+3678 - 222 = +3456, a funny number ).

Anyway, it's weird that the offsets differ on some discs.. maybe they used a separate device to add the logo?...

and maybe all discs start at the same sector after combined offset correction? if so, then it would be easy to convert a redump dump to a complete one: just insert zeroes after the original dump data up to sector 297143, then 550 sectors of 55's and then the logo data (if this data is always the same, including the RAW bytes?).

Also, I'm a bit confused.. the 'logo' area, is it the same area that is visible at the end of the disc when you hold it in the light? It has the same Sega logo written on there.

[themabus]

thanks!

Also, I'm a bit confused.. the 'logo' area, is it the same area that is visible at the end of the disc when you hold it in the light? It has the same Sega logo written on there.

yes,
when console boots up saturn will drive laser to this area and do few readings and if it's a backup - will fail.
so this final protection, it's very likely to be somewhere there.
i'm now very sure it's actually this logo, like RPS and few other people said (years ago ). because it's in CAV, this area is unlike the rest of cd.
every track consists of the same amount of frames (tracks do not get longer, closer to outer edge)

Console: SS
Tracks=~1460
FPT=2058 (2058/98=21 sec.) <|Frames Per Track

Console: DC
Tracks=~1226
FPT=1078 (1078/98=11 sec.)

so on backup this logo will never show up. it washes along the tracks and becomes garbage.
so i guess it doesn't matter how you pad it - to get logo, whole data would have to be recreated anyway, based on cd geometry.
would that work? - i don't know, it's unlikely, original is very precise (as can be seen in microscope,
i don't belive anyone could do that without proper hardaware)
maybe offset affects this whole process as well - i'm not sure. if it does, ther's 6 possible ways to pass data to circ
(one is correct, on four other ring will shuffle, like in those images i posted earlier).
and probably contrast on recorded media is too low to see anythig, anyway.
and maybe protection is something else after all...

also what's strange, sector count per track seems very low, compared to what i estimated from empty area. but maybe i made a mistake there.

i only had one DC ring, from European ChuChu Rocket. and it looks to be 1sample off. so you must remove 4bytes from the start of data
to get correct logo. but likely it's also my fault could be a bad dump.

Vigi, could you, please, check your DC rings?

i've uploaded the program here that will do circ delay lines and output ring to ASCII.
http://www.mediafire.com/?4hm1xyvojy2

syntax is:
ring2ascii.bat s 2058 10 RING_data.raw >SSRing
ring2ascii.bat s 1078 10 RING_data.raw >DCRing

i'll try to write something to reconfigure this data depending on cd in next few days,
maybe something shows up, some blured franken-image...

also, maybe new burners could write this logo easy, if you could specify CAV mode and speed,
i think, that's pretty much all there is.

[Jackal]

Ok, here's a package from Sonic Adventure:

http://rapidshare.com/files/129884698/sonic.rar.html

You should explain me how to open the ascii output (which tool are you using in those logo screenshots?)

[themabus]

thank you very much, Vigi!

i used Notepad++
it should have monospace font set by default, i think
ther's option to zoom out, under 'View', so you can go all way
it's slow tho, but good for overview

also you can just hit F4 in FAR Manager

..it's stupid, i know, but less coding...

[Jackal]

Dremora already helped me identify the tool



anyway, aren't we just extracting the printed ring text on the CD in bytes and turning it back into readable ASCII text? because both texts are identical:

TRADEMARK ''SEGA''      PRODUCED BY or UNDER LICENSE FROM SEGA ENTERPRISES LTD.

I guess we should start looking at the pregap instead?