...
As for BIOS chip, you likely mean a ZeroKey security chip. (The bios doesn't matter, as you can set the region once you upgrade your firmware anyway.)
I recently tried looking into why I can't boot Outrun_2_Special_Tours_512.bin on my Chihiro, I get an Error 05: This game is not acceptable by main board. The manual describes the following "Cause The game is a foreign edition"... "Countermeasures Use the domestic version of the game"
I have seen two solutions one of which does not work for me, and the other I can't quite find.
1. There seems to be a Region setting GDROM from NAMCO, has anyone got a copy of this image?
"
Region flash software, available in 4 fruity flavours, Japan, Export, USA and Unknown, like the Triforce/Lindbergh, the Chihiro uses a 1 byte bitmask to define region, for example 0xE is Japan/USA/Export, while 0xC is USA/Export only, and 0x2 is Japan only. Unknown is FF so can run ALL applications."
2. Use the software test menu? Most folks say you only need 30 pushes inside the System Information menu.
"Press the Service button 30 times in a row and a hidden menu will appear to change the region."
https://github.com/mamedev/mame/blob/master/src/mame/drivers/chihiro.cpp#L166
Others say 15 to open up the Game ID menu, and then 30 more to pop open the Region change menu.
"press the service button 15 times, you will notice "Game ID" appear at the bottom of the screen... press the service button a further 30 times and you can then edit the region."
http://www.ukvac.com/forum/how-to-change-the-region-on-a-triforce-and-chihiro_topic328500.html
I can get the Game ID change after 15 pushes, but adding 30 more does nothing, I don't get the option to edit the Region. I've not double checked the PIC in this Chihiro, but does it *have* to be a netboot pic specifically for this Region edit to work? I think this one was using a random PIC just to get past the startup requirement, but remained tethered otherwise. Is that perhaps my issue?
Likewise if anyone has detail on that magical Namco GDROM I'd be keen.