Saturn disks-A closer look.

croft

New Member
HI All :D

I am farely new to the forum and recently joined Sega extreme.

I must first thank Mal who has helped me very much with the Sega Saturn.

Mal you are one cool dude :smokin:

Last night i had the Sega Saturn to bits(again) and noticed a few interesting things.

I first thought that the outer ring on the disks was just holographic and doesnt do anything except act as a trademark.

I made a backup of my Original Japanese Guardian heroes and the rip was fine.

Later on i found a Sega rally disk(pal) lying around and thought"what the heck" lets do some experamenting. :huh

I took the Guardian heroes disk and where the data had ended i cut the rest of the disk off completely.

I then stuck this to the sega rally disk on the underneath.

Placed the disk in and had no luck.The machine was trying to look for the outer rings etc and i dont think it could focus on them,Or it may be that the Sega rally was a uk copy.

I then stuck Guardian heroes in by itself (backup)) and watched exactly where the laser was trying to focus.It was right at the very edge where the data ends.I then looked closely at my Original saturn games and there is an extremely fine line near where the data ends,this is then followed by the holographic ring.

I watched how the laser tracks this very thin track and then jumps to the extreme outer edge where the hologram and trademark are.

It looks like the Sega Saturn looks at 2 peices of information on the disks.The first outer track seems to push the laser towards the outer edge.Is the first track some sort of region check?

With the holographic image i had a look under a magnifying glass and there are literally hundreds of very odd lines,I cannot see how this could be data beacuse i am not aware of any laser mechanism in the world that can read holographic images yet.Maybe the chip looks for a certain wavelenghth as the laser rebounds of it?

I origianlly thought that this outer rim did nothing but i did notice the laser does radically move over it.

I then reversed the cd mod but this did not work beacuse the bottom cd was to close to the disk mechanism(beware :blah )

I have heard of the disk swap method and this gave me an idea.

How about a switch aplying to the lever which tells the saturn when the lid is open,So access can be made while the lid is up.

Also a switch aplying to the mechanism etc which spins the disk,This then could be stopped just after the security has been checked,Backup placed inside and switched back again.

I thought this process would stop people having to pull disks out while the motor is spinning. :unsure:

With my first process i would say that it is possible to take an original disk and cut the outer rim off and aply it to your backups of your origianls.

But the disks need to be level so the laser can track each peice of info.

I think this is easier said than done,I butchered the Sega rally disk with a pair of very sharp scissors.

I will carry on with my experimentations,

Whoever desighned the Saturn software must be one hell of a programmer?

Regards,

ian. :slap
 

antime

Extra Hard Mid Boss
Before you destroy your hardware I recommend you browse through the old threads on the subject.
 

croft

New Member
Hi All, ;)

Many thanks for the information and the links,I am very greatfull. :thumbs-up:

It has amazed me how much info is out there :huh: .

I am interested in the option of using VGA on the Sega Saturn,This would be amazing.

I use the Dreamcast on a 21"Mitsubishi Diamandtron and it is awsome.

Amazing how the saturn is full of neat tricks. :flamethrower:

Has anybody actually built a system of stalling the laser with a switch etc?

It also would be intresting to have 2 saturn machines,Run a scope on the chip when the data has been extracted from the securety check and make a note of the correct code,Maybe then bridging the 2 pcb boards so that the machine that has loaded the info passes this on to the second machines chip. :sarcasm:

Thanks for the thoughts on the Sega disk that i destroyed with a pair of scissors. :eek:wned Will try not to ruin to may more. :smash

Sega reps"please give us the information that we want",The machine is no longer for sale and we just want to back our favourite games up :puke:
 
I think it's more out of fun then to just have one that isn't modded play backups....modchips are an easy fix so ppl can jus as easily throw one of those in.
 

Alexvrb

Member
Actually modchips are a PITA, for those with (certain?) 64-pin saturns and/or (certain?) modchips. Also for those with unmodded model 1 systems. BUT, having said that, it is the ONLY solution other than swapping. I doubt anyone does it because they don't have another method of playing backups/homebrew, so it is probably just for the experience. But if they succeeded they could help others out.
 

ExCyber

Staff member
With the holographic image i had a look under a magnifying glass and there are literally hundreds of very odd lines,I cannot see how this could be data beacuse i am not aware of any laser mechanism in the world that can read holographic images yet.
It's almost certainly data. The "very odd lines" you're seeing are probably the channel.
 

croft

New Member
THANKS FOR THE INFO ;)

Its intresting to look at the lines and figure out what they do?

You mentioned Channel,

Please exscuse as my Saturn knowledge is fairly small.

:huh
 

croft

New Member
Thanks Excyber for the info.

If the holographic image does contain data i was wondering how the chips intercept this.

Do they stall the Saturn into not making the data check :unsure:

I heard that the rim was "sil screend on".If so the silk screen machines must exist somewhere.

Anybody out there know about silk screening holographic data on to cd,s :bow

The laser lens does move extremely radically when it hits this rim.

Could it be looking for a reflective wave length patter instead of data.

I have read the forums on this site and the Sega machine must be the hardest one to crack.In one respect the disks cannot be read all the way to the edge via conventional pcs but the Saturn does this with ease? :damn:

I did read that one guy reported that a Sega rep stated that the track contains no data at all.

Has anybody thoroughly examined the chip itself and how it operates,

Will carry on exploring as this machine has to be cracked if its the last thing i do. :slap

Thanks,

I.H. :bs
 

ExCyber

Staff member
You mentioned Channel
The "channel" is the physical track on CDs which contains the data. I might be using this term incorrectly; now that I think about it I'm not sure whether it refers to the physical track or the datastream it encodes...

If the holographic image does contain data i was wondering how the chips intercept this.
The image (not holographic, AFAIK; the weird appearance is probably due to small areas of unlike diffraction) is probably formed by carefully positioned runs of short/long pit lengths, as suggested by Sega's patent on the protection, which describes this approach as being preferred for cost reasons over an optical recognition system.

I heard that the rim was "sil screend on".If so the silk screen machines must exist somewhere.
I'm not sure this is really compatible with the way CDs are made. It would also be pretty expensive.

The laser lens does move extremely radically when it hits this rim.

Could it be looking for a reflective wave length patter instead of data.
Well, data on a CD is a "reflective wave length pattern", so I'm not sure what you're asking. As for the radical movement, my guess is that it reads different areas of the signature unti one "chunk" comes through clear. I seem to remember the patent mentioning this approach for reliability.

Anybody out there know about silk screening holographic data on to cd,s
I've never heard of this being done.

I did read that one guy reported that a Sega rep stated that the track contains no data at all.
The Sega rep probably didn't know what he/she was talking about. You're not very likely to run into a person who knows about this kind of stuff outside of the hardware engineers who actually worked on the system, as the details of the process seem to be bottled up inside the CD reader MCU.
 

croft

New Member
Hi :)

Thanks for the info.

Really helpfull,

I wish i had joined the forum months ago. :blush:

Amazing insights and discoveries on Sega extreme.

Have made anote in my mind of the info,

Exellent :cool:
 

ExCyber

Staff member
Since you seem to be really interested in figuring this out, I went into the USPTO database and tried to dig up the patent - I think it was this one (go here and enter number 5627895 if the direct link doesn't work). You'll likely need a TIFF plugin such as Alternatiff to look at the figures.

edit: Long story short, if you happen to know anyone who does serious CD hacking work, see if you can get them to try dumping a Saturn CD while ignoring the TOC (there are programs that support this, but the CD reader firmware normally doesn't allow it). I suspect that what's happening is that the discs essentially have a huge postgap with the ring graphics encoded as data at the end.
 

croft

New Member
Hi Ex Cyber,

Just got to the link page with the info on.

Super cool,Thanks very much.

Will have a read of all the info,

Full respect to you :thumbs-up: :thumbs-up: :thumbs-up: :thumbs-up: :thumbs-up:

Super....
 

antime

Extra Hard Mid Boss
As long as we're talking Saturn discs, I thought I'd bring up this again: this is an unfortunately poor scan of the underside of the US version of Dark Savior. The thin dark band is the gap before the logo area, but if you look to the center you see part of a thicker, light ring with a pattern that is repeated across the circumference of the disc. Is this just something added to combat counterfeiters or does it serve any technical purpose? Do any other games have a similar "second ring?"
 
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