Question about Saturn CD part.

[TmEE]

You have unmodified Saturn, you enter a burned disc in it, it gets rejected... but will the drive remain functional or is "locked" until you insert audio or game CD ? I have no idea how much the SH1 will do for you in the Saturn...


I will start messing with Saturn after my current MD business is done, and I like to think ahead...

 

[ExCyber]

I'm not the expert here, but my understanding is that if a disc has a Saturn header, then the SH-1 will not allow reading beyond the header (until a successful ring check), and if there is no Saturn header the disc can be read without restriction.

 

[TmEE]

This is very relifing, I hope things work so

 

[vbt]

This is very relifing, I hope things work so

Ex-Cyber is right. If you make a regular CD without an IP.BIN you can access the data of the CD from a binary loaded in to memory after unlocking it (good old function CD unlock).

 

[antime]

If it really is that simple, you'd have thought there would be pirate carts by now. Ie. wipe enough of the static part of the header so the disc is no longer recognized as a Saturn disc, then have the cart load and run the game instead.

 

[TmEE]

I intent on doing Saturn dev from the cartslot, and knowing you can use CD for data makes things nicer.

 

[Amon]

That would be a good way to release a game. Use a cart/cd combo, with data being on both binary and what not on the cart.

 

[ExCyber]

That would be a good way to release a game. Use a cart/cd combo, with data being on both binary and what not on the cart.

Good from a technology standpoint, but pretty expensive. The memory alone is far more expensive than a CD, then you also have to get the actual cartridge fabricated and assembled. Some kind of alternative header format (as I recall, the winning suggestion was that we should change "SEGA SEGASATURN" to "SEGATA SANSHIRO" and leave everything else the same ) supported by a replacement AR firmware would probably be the way to go.

 

[Amon]

Unless someone cracks the security ring this seems like the only option to release something that EVERY saturn can use and play.

 

[TmEE]

I'm getting a AR cart soon, I'll dump its ROM (or someone can provide a dump) to see what is done so that it is bootable (Dev docs are very silent about the cart part...). I'll be ending up making my own cart (basically an adaptor so I could use my MD flashcart http://www.hot.ee/tmeeco/EEPROM/INACT.JPG )

 

[ExCyber]

The cart just needs to have a header similar to the CD header, and the BIOS will jump to it (IIRC, the entry offset is 0xF00 in A-Bus CS1 space, which I can't remember the base address of right now). The way that the AR boots Saturn games is a bit trickier, and I'm not familiar with the details (AFAIK it actually runs the BIOS CD booting code, but interrupts it with the User Break Controller in order to patch the region code and load the cheat routine). Firmware images are available in the upgrade/tools packages from Datel and EMS. Despite the fact that they distribute the firmware images themselves, there's "protection" against dumping the firmware using the standard commlink protocol commands, so if you want to back up the firmware on your cart you'll either need to write your own dumping program (not hard) or a program that patches the in-RAM copy of the firmware to bypass the protection (I think one of Charles MacDonald's docs shows the relevant chunk of asm).

 

[antime]

The BIOS will "load" the IP from the cartridge and execute it from workram, just like it would from a CD.

 

[Amon]

Im running on no sleep so I am guessing this is a dumb question is there any way to get an ar4in1 to boot a burned saturn game without a mod chip through some means of the ip.bin not being on the cd but somehome read by the ar such that the saturn wont lock the drive?

 

[antime]

I don't think anyone's tried. I doubt it would be that simple, though.

 

[ExCyber]

It should be possible by modifying the disc header, but I think it would be tricky. There are basically two approaches:


1) Write a new boot routine that handles everything while maintaining compatibility with games.


2) Trick the Saturn BIOS into treating the game as a Saturn game while preventing a ring check.


If an unlock command has to be issued regardless of which kind of CD is being read, then it seems like it should be possible to do something similar to the region bypass to convince the BIOS that it's a normal Saturn game...

 

[antime]

Add at least 3) Hook the CDC vectors so that games that issue ring checks after booting don't fail (or remove the additional checks from the game code).