Yeah, so I hacked the Sega Saturn Bios and removed regional lockout and CD authenticity checks. Obviously, that was the reason I was dying to get a Saturn a couple of days earlier. Thanks to an unnamed individual, I've got one now and promptly installed that modified Bios.
Good news first: regional lockout bypass works just fine on real hardware.
Install this Bios in your Saturn and play any authentic game in any video mode you like, no need for clunky switches or cartridges anymore.
The bad news: Although the CD authenticity checks in the Bios have been removed, CD-R copies still don't boot.
I basically have zero debugging capabilities on real hardware, so I can't really tell what the exact problem is, but credible sources suggest that the CD interface has to be unlocked by initializing with a genuine Saturn disc before being able to boot a game disc. This is rather unsatisfying, but I'm releasing this anyway, it's better than nothing.
I'll be getting a modchip for now and will have a look at this again once Dr. Decapitator has dumped the CD interface program ROM.
I could imagine that there's a debug command hidden somewhere that lets you boot CD-Rs without authenticating first. We'll see...
Also, if you plan on installing this Bios in your Saturn, keep in mind that the pinout of the original Bios maskROM is similar to the 27c800 and don't forget to byteswap the ROM before copying it to a 16bit Eprom. Btw, this hack is based on the japanese 1.01 Bios.
Guys - I totally need a Sega Saturn, and fast! This is an emergency!! A matter of life and death!!! Humanity is at stake!!!!!!11 Ok, not really, but I'm dying to get one and they're rare as fuck here - so, if you're living around Cologne, Germany and happen to have one(working or not) for sale, contact me at firstname.lastname@example.org and I'll pick it up immediately. Thanks!
Yeah, and I don't even like the Mega Drive all that much...
Anyway, here's the story:
A friend of mine asked me if I could help him install a switchless multinorm mod in his Mk1 Mega Drive and passed me these instructions by mmmonkey.
Sure, why not?
Program a PIC microcontroller, solder 8 wires and be done with it, piece of cake.
Or so I thought.
As it turned out, the PIC code (which was originally created for a Sega Saturn mod) didn't work on 80% of my 16F630 chips for no apparent reason.
It wouldn't even boot on them, no matter what, even though my own programs ran perfectly fine on these chips.
Next, the Mega Drive that was about to be modded turned out to be an early Mk1 unit.
In contrast to all later models, these use active-high reset logic, which the author of above page tried to tackle with this behemoth of a mod that, even though it surely took a lot of effort to develop, seemed a bit excessive.
Obviously, a clean solution to both problems would be to create my own mod, including a working PIC program that would run on all Mega Drive models without any additional parts.
The focus here lies on simplicity.
There are just three auto-saved modes here indicated by the color of a status LED: