Saturn proof-of-concept bootloader Pseudo Saturn

You just have to use writable memory - the only thing that's required to make it bootable is that it has a valid application identifier block at the start of the ROM and the correct magic binary data stored after that, so it's entirely a factor of what you program into it rather than the type of memory device used.

If the code is 256KB or less (which seems very likely) you don't even need to make a full-width board, since most of the A-bus signals except for some high order address lines are on one half of the connector.

 

Pretty much. I'm not doing anything particularly special to boot code off the cart. You could probably base a design off existing schematics(like antime's usb flash cart) and then flash your own custom code with whatever features you want.

 

Just on a technical level so that I understand this correctly.
When an unodified Saturn reads a CD-R w/o the wobble but the "SEGA SEGASATURN" string in place, it does reject the disc, correct?
But with a patched image and bootloader containing patched strings, it eats the disc without complaining ? Wouldn't that be exasctly the same case as above?

How come the disc doesn't get rejected in this condition ? Which part of the security gets bypassed here?

 

My understanding is, that discs without the "SEGA SEGASATURN" string are treated as VideoCD or audio CD's - i.e. you can access the fill disc, but it wont boot a game from it.

The bootloader on the AR card accesses the disc and boots it. Discs with the string are outright rejected as its a copy.

 

Correct

Not quite the same case. Basically the CD Block determines what security scheme to use depending on the type of disc. The way it determines whether the disc type is a Saturn disc vs some other kind of data disc is by the "SEGA SEGASATURN" string. So by changing that string on a disc when going through the authentication process it doesn't do the extra checks and just unlocks it. The other part of the security is in the bios which also checks to see if "SEGA SEGASATURN" is present. The boot loader still boots "SEGA SEGASATURN" disc if present, but also checks for the custom string in the patched discs. It also doesn't do region checks.

 

I was going to test this out but I got an error 9 when going for the flash

Booted the CD fine via the Action Replay 4M Plus cart (2 swap trick CDR Original then back to the CDR)

The newer version of the AR4M+ with no back port

 

So, what about if you were to change the string to say.... "SEGA SATURNSEGA", this should bypass the additional checks - right?

Then change the bios check to boot discs with that new string. In theory, allowing backups with just a bios swap and patching the ISO first?

 

What is the custom string?

Also the full error I am getting on trying to flash the cart is "Error detecting cart. Err code = -9"

I checked to make sure I could flash it at all... forgot to back up my saves but no great loss I wanted to start a couple of the games from scratch anyway but also wanted to make sure I could revert the firmware back to 2.02

I may check and flash that from a SGM disc (Save Game Manager) it also has a flashing tool

My cart is detected as
Flash Ven BFBF.
Flash Dev 1010.
Vendor: Silicon Storage Technology
Unknown Device ID - proceed with cau (presume that would say "caution" if it fit)

I can do a capture of my Saturn running this if I can get it running that is

EDIT:- It did flash ok with 2.02C update and I checked it to make sure it was not bricked and my code count went up as it did

EDIT:- before I commit to flashing this I did have a quick look at PseudoSaturn.BIN in hex (was hopeing I could figure out what you replaced the "SEGA SEGASATURN" string with but was unable to figure that out anyway) and noticed it has some of the flashing instructions inside this as well as a few codes, so I am wondering if the rom is correct or if it has some code left in there that should not be there

 

Congrats about this, amazing hack!

 

Sorry for asking but, is it required to hack my action replay 4M Plus to use it or no need too at all?

 

Did you read the instructions? The answer is completely obvious if you did.

 

Not anymore, but this is cheaper than buying a modchip.

 

Someone in this thread mentioned to patch this string in the BIOS (together with the region free patch).
Is it possible to do it on this level ? That would be pretty cool because it would bring the 2 most asked for features into one solution ... probably even for the lowest price.

 

Does anyone make Saturn cart pcbs and sell them at a reasonable price? Although you wouldn't have the RAM expansion, you could atleast make something to boot these patched burns and imports.

It would be a nice idea for the BIOS replacement mod to hack it to check for a second string when it comes to booting games. Maybe that reordered SEGA SATURNSEGA. Then you would have it all, import capability and CD-Rs. Ofcourse replacing the BIOS isn't the easiest thing to do but it could be done.

 

Finally got round to testing this fully

I couldn't flash with the installer.iso though as detailed in post #48

I did notice you fixed the disc patch though, though I had already figured the exact string replace anyway but the patch does save from manually patching the string plus no extra fixes needed with CD-Mage ect, so big thanks for that

53 45 47 41 20 53 45 47 41 53 41 54 55 52 4E 20 SEGA SEGASATURN
50 53 45 55 44 4F 20 53 41 54 55 52 4E 20 20 20 PSEUDO SATURN
20 = a space (so PSEUDO SATURN is followed by 3 spaces)

If you are keeping your disc images in a format that is not currently supported by the patch then you can do that by hex then fix it via CD-Mage (More details further back in the thread for CD-Mage)


I flashed with a custom atlas disc though built via VirtualBox with XP installed, that kinda sucks as the builder was not compatible with 64bit win7 (I could share that if anyone wants it now though (iso+mp3+cue format, or I can re image that, in bin+cue), it also has the AR4M+ 2.02C bios on there as well as this one, if you wanted to restore the AR4M+)

Anyway I just used 3D Lemmings EU as a quick test (I'm not a fan of the game or anything what did they do to the classic lemmings I loved so much) it boots just fine

I will make a video capture of my Saturn soon though to show off this masterpiece in action, not the game, but work of Cyber Warrior X.

I take it the debug mode has no use to the average user

I am a little curious about multi disc games, in that will that swap discs fine with this mod or has it yet to be tested, or do the games have a end of disc save feature like Final Fantasy 7 to 9 has that let you create a save for the next disc (yet to play any as of yet from backup anyway [multi CD games that is])



For the sake of extra info

Saturn = Model 1 [PAL][E] (too lazy to look at it more that for now though)
Cart used = Action Replay 4M Plus (later version with no Comms port)
Flash Ven BFBF.
Flash Dev 1010.
Vendor: Silicon Storage Technology
Unknown Device ID (Presume that is why I get problems with the installer?)


EDIT: Another quick game test X-Men vs Street Fighter JP this time, boots fine on my PAL console (I did add a region display switch though, very very easy mod even for those that are new to soldering or just not very good at it) that game also needs ram so the ram functions of the AR4M+ are still working with this bios so only missing codes and backup flash

 

Could I bother you to try Panzer Dragoon Saga? It's been a while, but I seem to recall getting it to boot with the swap trick, but then it'd run into some kind of additional protection shortly after starting a game. (Maybe it was just a semi-bad burn, not sure, didn't investigate it back then.)

 

Well I just re-found this page with a schematic and even gerber files to order the PCB and was hoping Trimesh or someone else with enough knowledge could confirm that this guys setup could be used to make the boot cartridge. Obviously there will be the RAM and other functions missing but as a boot cartridge it promising if it fit the requirements.
http://koti.kapsi.fi/~antime/sega/usbcart/usbcart.html

 

Was that something like the FMV plays but after that, it reboots the Saturn? If so it just sounds like you did not burn the audio track/s or possibly done a single swap trick instead of the double swap trick that would result again in only reading the data track

I can test the game but need to know what the issue was before I can verify it working or if the issue remains

 

Video of this booting a disc

It's a Console capture rather than from a video camera



It's not a public video or anything, so just for here at the moment

 

Is there any way to restore original AR Rom (eg reflash with original? Are there any AR flash dumps avadible)?