What the R422 mod actually does

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KillerBean2
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What the R422 mod actually does

Post by KillerBean2 » Fri Apr 18, 2008 1:48 pm

Some people think the R422 mod is a 50/60 Hz mod, but that's definitely not true.
(The scanrate is determined by the sofware in the BIOS and can't be changed without some BIOS tinkering)

Most people think it makes a US/JAP Dreamcast output its video encoded as PAL, but that's only partially true. I tried the mod, did some testing and came to the following conclusion:

The mod makes the Dreamcast forget about its own PAL/NTSC setting and forces it to "follow" the inserted game.

This means:

US/JAP Dreamcast + R422 mod + US/JAP game = 60 Hz NTSC
US/JAP Dreamcast + R422 mod + EU game = 60 Hz PAL
EU Dreamcast + R422 mod + US/JAP game = 50 Hz NTSC
EU Dreamcast + R422 mod + EU game = 50 Hz PAL


Can anybody confirm this?
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Re: What the R422 mod actually does

Post by Ex-Cyber » Fri Apr 18, 2008 4:56 pm

Are you sure that the BIOS doesn't read some kind of hardware register (whose state could be set by R422) in order to determine which video mode to set? It seems like it would be preferable (in terms of inventory management) to have a universal BIOS and PCB and just set the region by placing/omitting resistors.
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KillerBean2
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Re: What the R422 mod actually does

Post by KillerBean2 » Sat Apr 19, 2008 3:17 am

Well, you'd think, that's what they'd do, since that's the case with all of their previouse consoles. But I seriously think Sega went with a all-BIOS-internal-settings solution, when they designed the Dreamcast. It seems to me, that the R422 mod doesn't change a bit (so to speak) in the video settings. It just tells the video hardware to read the settings string somewhere else... don't ask me how. All I know, is what my eyes tell me:

When I put a JAP or US game in my R422 modded Dreamcast, it outputs in NTSC.
And when I put a EU game in the same Dreamcast, it outputs in PAL.

Hence my "following" theory.

Is it just me, who's going crazy?
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Re: What the R422 mod actually does

Post by Lyris » Sun Dec 21, 2008 2:45 pm

I modified a European Dreamcast by connecting R512 to +12v and running region changer.

Before the mod, the 60hz games ran at PAL60. I don't like this because the DC PAL60 output is weird-looking over S-Video (luminance of the colours doesn't seem correct), and I have to use S-Video until I get a new VGA box.

After the mod, setting the video to NTSC in the Region Changer program gives real NTSC 60hz video. Bridging R422 gives PAL60 instead.
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Re: What the R422 mod actually does

Post by FamilyGuy » Sun Dec 21, 2008 3:41 pm

Personnally, when I made the region changer mod a year ago, I've tried the r422 trick, jsut to see what it acutally does.

With a ntsc console flashed to PAL my screen flickered and was in black and white.
With a ntsc console flashed to PAL and R422-mod enabled, my screen was in black and white but wasn't flickering anymore.

Has I have no real PAL games I use a backup of Sonic Adventure that I've made (JUE patched).

The fact that the screen is in black and white means it's outputting PAL video (NTSC TV can't understand what's goin on witht he color). But the flickering screen means it's in 50hz, the stable screen means it's in 60hz.

I hope that little observation could help you :P

FG
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Re: What the R422 mod actually does

Post by petterk » Thu Feb 17, 2011 11:32 am

-=FamilyGuy=- wrote:Personnally, when I made the region changer mod a year ago, I've tried the r422 trick, jsut to see what it acutally does.

With a ntsc console flashed to PAL my screen flickered and was in black and white.
With a ntsc console flashed to PAL and R422-mod enabled, my screen was in black and white but wasn't flickering anymore.

Has I have no real PAL games I use a backup of Sonic Adventure that I've made (JUE patched).

The fact that the screen is in black and white means it's outputting PAL video (NTSC TV can't understand what's goin on witht he color). But the flickering screen means it's in 50hz, the stable screen means it's in 60hz.

I hope that little observation could help you :P

FG
So this means that a PAL dreamcast with the r422 mod will display PAL60 as default?
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