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Recommended BIOS version for NAOMI 2

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freddiefiasco

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I am currently using EPR-23607B for a NAOMI 2. I found that running Guilty Gear XX Accent Core requires EPR-23605C in order to run. I have more games that require 23607B than 23605C. Is there a specific BIOS version that can run both 23607B and 23605C games without swapping out the EPROM?
 
I'm running the multi bios on my naomi 2. I haven't had an issue running anything on it.
 
The MultiBIOS is rev C which is the highest NAOMI 2 BIOS rev. I know that all NAOMI 2 games work well on it but I haven't tested out all NAOMI 1 games with it.

Are the games that require Rev B due to region requirments or do they not work on Rev C in general?
 
Pretty sure I used VF4 with a multi, but I sold that cart.

I don't know of any games which require non-JP region that won't work with the multi bios.
 
twistedsymphony said:
Are the games that require Rev B due to region requirments or do they not work on Rev C in general?
Click to expand...
afaik no.

probably he used Rev.B because it is latest available USA Naomi 2 BIOS,
currently I tend to think Sega not released Naomi2 BIOS Rev.C for US at all.
 
Has anyone made a bios switcher for the naomi like the one for the stv? I know there is a multi bios that works with the dip switches, but I would much prefer a solution like the st-v switcher.
 
Derick2k said:
Has anyone made a bios switcher for the naomi like the one for the stv? I know there is a multi bios that works with the dip switches, but I would much prefer a solution like the st-v switcher.
Click to expand...
Theoretically you could burn 2 images back to back to a 27c322 and put a switch to change the highest address line between 5v/gnd but I've never bothered to try it.
 
yep, digging through that code was quite amusing :)

this code also have odd enable trigger - if you look at very end of N bios you may see there "COPYRIGHT (C)SEGA blah blah blah", this text is compared against another one from bios (which is in obfuscated form, in reversed order), and if it will be *not* the same - DIPSW region switching will be enabled.
(in regular bioses they are the same, so this never happen)
not sure why and that for Sega did this...

PS: for those who may be not aware - p1pkin is my nickname @ ArcadeOtaku ;)
 
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MetalliC said:
yep, digging through that code was quite amusing :)

this code also have odd enable trigger - if you look at very end of N bios you may see there "COPYRIGHT (C)SEGA blah blah blah", this text is compared against another one from bios (which is in obfuscated form, in reversed order), and if it will be *not* the same - DIPSW region switching will be enabled.
(in regular bioses they are the same, so this never happen)
not sure why and that for Sega did this...

PS: for those who may be not aware - p1pkin is my nickname @ ArcadeOtaku ;)
Click to expand...
Thanks for the multi bios!
 
welcome.

there was a story behind of it. strictly speaking - it was never was a problem to write some homebrew code and inject it into Naomi (or Dreamcast, etc) BIOS, the problem was get it running on real hardware, because of BIOS sum protection implemented in hardware, inside of HOLLY chipset, and preventing BIOSes from being modified.

that was real problem, until one good person (Arzeno F.) found House of the Dead 2 prototype cartridge and BIOS, dumped them and shared. during analyze of this BIOS I noticed Sega engineer's security fuckup, and see how chunk of this BIOS can be used to make other ones "moddable/editable".
so in result it made possible things like "Naomi multibios", Japanese Cake's DC custom BIOSes, ROM dumper for SystemSP...

so, the moral is: then you spot some interesting or unusual looking thing - dump it and share to community, not hoard or sell to some unk collector with zero chances it becomes public.
 
MetalliC said:
twistedsymphony said:
Are the games that require Rev B due to region requirments or do they not work on Rev C in general?
Click to expand...
afaik no.
probably he used Rev.B because it is latest available USA Naomi 2 BIOS,
currently I tend to think Sega not released Naomi2 BIOS Rev.C for US at all.
Click to expand...
You are correct. I am using the Latest Revision for US Naomi 2 BIOS. I am just discovering that Naomi 1 games can run on Naomi 2 and found a cart I wanted to run but it needs the Japanese revision. :)
 
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