[dodge32x]

Hi everyone.

I investigated BIOS Sega Saturn, and have thought that, possibly to change it, it will allow
For games of all regions and backup copies on CD-R.
It was possible to change BIOS to disconnect check of regional accessories
Disk, but it was necessary to check up fashion on the real console.
I have found comes nearer EPROM 4M-BIT [512K X 8/256K х 16], it is very ancient EPROM,
I managed to find only on Ebay.
Tests have passed successfully, I Saturn play games for all regions. Similar Playstation Pure Yaroze.
It is very convenient, and don't demand for switching of regions or demountable trick.
Besides, I would like to disconnect in BIOS checks of authenticity of disk what to play backup copy of CD-R,

This post has been edited by dodge32x: 20 January 2010 - 05:05 PM

[slinga]

What version(s) of the BIOS does this work against? In the screenshot above it appears to be an older, gray Japanese saturn.

Are you patching offsets in the BIOS on the fly? If so what addresses, I might want to take a look at it some point. Anyway cool stuff, congrats on your find.

This post has been edited by slinga: 27 December 2009 - 08:17 PM

[dodge32x]

[slinga]

Can you explain how the CD drive is unlocked (i.e. made to think a the security ring is present)? I didn't think there was a way to unlock the CD drive without having the security ring present, even if you controlled the BIOS.

As for helping, I'm not much of a hardware guy at all. Just curious to see how the BIOS functions.

[Piratero]

CyberWarriorX has done extensive work on this as well.

How much of the BIOS did you modify? Did you add any routines?

[dodge32x]

I modified all bios that I have.
I have added the modification - (Region Free), I can not modify for start CD-R, in this modification I need the help.

Hi-Saturn BIOS (J) (1.01).bin
Sega Saturn BIOS (E) (1.00).bin
Sega Saturn BIOS (J) (1.00).bin
Sega Saturn BIOS (J) (1.01).bin
Sega Saturn BIOS (UE) (1.00a).bin
V-Saturn BIOS (J) (1.01).bin

[ExCyber]

As far as I know, the CD-R lockout is handled by the CD block firmware, which is in a ROM inside the SH-1, and so can't be altered. Unless you discover some kind of test command that lets you read/write the SH-1's work RAM area (and then figure out where it stores the "disc verified" flag), there's probably no way to do it from the SH-2. The other approach that I've never seen confirmed/denied working is to modify the header check so that it recognizes and boots a disc with a modified header (one suggestion was to have "SEGATA SANSHIRO" instead of "SEGA SEGASATURN" :) ). This way, the CD block doesn't recognize it as a Saturn disc.

[slinga]

Any one have a dump of the CD block firmware? Any notes, docs? Can't be that much assembly to look at.

[ExCyber]

slinga, on 06 January 2010 - 10:24 PM, said:

Any one have a dump of the CD block firmware? Any notes, docs? Can't be that much assembly to look at.

As far as I know, it hasn't been dumped. It's on Guru's decap list, so it's probably only a matter of time before it shows up in the MESS BIOS set...

[slinga]

Any value in analyzing the official boot disk? I never had it (or bothered to download the iso) so I can't comment on it. I guess you could RE it and figure out the commands it issues to the CD block. Might be the next best thing to REing the CD firmware itself.

Also, if you use the boot disk and do the swap trick, can you then boot a burned CD? If so that's incredibly interesting.

[dodge32x]

This part of code is responsible for CD check.

Sega Saturn BIOS (J) (1.01).bin
Find - 880489037F08
To change 880389037F08

After that changes, Saturn won't start even original CDs.