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Puting A Different Dvd Drive In A Xbox With A Softmod |
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| Bomb Bloke |
Apr 22 2009, 03:17 AM
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X-S Transcendental
         
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Xbox Version: v1.0
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I'm pretty sure X-Box discs are written in the correct order, though there are a lot of rumours flying around that GameCube discs are back to front (apparently they're wrong too).
Though when I put a GameCube disc in my PC, it will literally stall until I take it out.
In both cases I'm not really sure why a computer can't read the disc. In theory, blindly reading every sector off the disc should work. It doesn't.
The Sega Saturn has an interesting copy protection measure. There's a holographic rim around the edge of the disc, which simply cannot be replicated with a standard burner. Makes sense as to why those can't be copied.
PS2 discs, on the other hand, can not only be browsed in Windows Explorer, but a PC can quite easily backup/copy the entire disc with no special drives/firmware. A softmodded PS2 will boot these quite happily (though you might have to patch the ISO prior to burning).
As to why an X-Box DVD drive will accept burnt discs? Well, the truth is that it doesn't; you put one in and it tells the system that it's not a legal disc, but since the mods we use change the system's actual BIOS, the console goes "who cares?" and runs the game anyway.
Compare this to the 360, where you can flash the drive's firmware to make it report burns as valid discs. The system's still paying attention to security, but the drive's feeding it false information.
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| lordvader129 |
Apr 22 2009, 06:08 AM
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He Who Posts Alot...
              
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IIRC xbox discs are in fact read backwards, the reason a PC drive cant read it is because it reads the outer section (which is a dvd video telling you its an xbox game, and instruction you to put it in an xbox to play it) and then its a hard "end of disc" marker so it doesnt read any farther
xboxs read from the inside and see the game before the dvd-video (then later hit the end of disc marker and never get to the video portion)
for a backup, it only has the one region, the game, so it reads (maybe the inside out, maybe from the outside in, who knows) and eventually find the default.xbe, and runs it
if its an unmodded xbox one of two things happens, it hits the xbox and tries to run it, if its signed it runs it, but the media check within the xbe prevents the game from playing, if it has been media patched its signature is no longer valid, so the stock bios doesnt play it
for xbox1 modding, the hacked bios ignores the lack of proper signature, for a 360 the firmware patch counterfeits the media check and reports a proper, retail pressed DVD instead of a dvd-r
for PS2 the media check is not the in the executable, but in the ps2 firmware itself, thats why burned movies wouldnt play on old ps2s (i think they later updated it so it would play dvd-video from a burned disc, but not ps2 games)
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| Heimdall |
Apr 22 2009, 09:21 AM
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X-S Legend
        
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Done a bit more digging, and some thinking.
CDs / Conventional DVDs read from the inside out, Xbox DVD drive reads games from the outside in. Your PC DVD burner burns from the inside out regardless of whether it's burning a standard (PC) disc or an Xbox disc. I just checked with all my boot / rescue discs, and burned the latest AID to double check, and you can see the location and size of the various burned areas - they all start from the inside of the disc.
I've also taken the latest AID, opened it with Magic ISO (it will happily open Xbox iso images), and resaved it. When I burn that the Xbox sees it as a data DVD.
Consequently, I conclude that Qwix must reverse the order of the data in the iso image when it saves it. The Xbox tries to read the disc from the outside in, and if it gets valid data - which it will if the image file is reversed by Qwix - it concludes that the disc is a game. If it gets invalid data it tries reading from the inside out, and if it now gets valid data it concludes that it's a data disc.
If you try to read the same boot / rescue disc in your PC (for whatever reason) it reads it from the inside out, and doesn't recognise it as a valid disc because the data is reversed.
And for an original Xbox game disc there are two sessions, as Lordvader describes - an outside-in session containing the actual game, and an inside-out session containing the video. The Xbox reads from the outside in and sees the game, your PC reads from the inside out and sees the video.
I'm still a little sceptical about this plus the digital signature being the totality of the security on an original Xbox disc, for a variety of reasons - especially the security around media checking - so I'm off to do some more digging.
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| Bomb Bloke |
Apr 22 2009, 11:02 AM
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X-S Transcendental
         
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I gather there are different file systems you can use when burning discs. For example, to memory one of them doesn't support files larger then 2gb, while others do. (I have a memory that XBMC can't read all of them, and I know PCSXBox won't read proper PSX discs - XPort did the coding required, but apparently the read rate was so slow that he left it out of the actual emulator).
Could well be that proper discs don't have the game data around the outside, they may well be like our burns; all the actual tracks are near the center, and the outer areas around the rim of the disc just get ignored (as opposed to having a great big gap between in the video/game tracks).
Standard multi-track data discs are another anomaly. If memory serves, the only track the console will read is the last one.
(These days people don't use them so much, but back in the day discs cost more and it was often prudent to add more data to an old burn then to pull out a fresh one each time. Not all PCs would register the original tracks though, and if you did it wrong the original tracks would be hidden (though still accessible if you had the right software)).
Bah, too many different discs/formats for my mind!
This post has been edited by Bomb Bloke: Apr 22 2009, 11:04 AM
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