Give a big thanks to 6502freak for supporting VRC7 audio for our PowerPaks. :DDD/

More excitingly... He has also enabled a little feature recently to swap between VRC7 and OPLL mode for the NES/Famicom. ;)

What this means is you can basically turn the NES/Famicom into a Japanese SMS. You get all 9 OPLL channels, rhythm mode, and use the patch sets provided by the OPLL.

It works by regular implementation of VRC7's hardware access registers but referring to the OPLL datasheet instead.

In order to set between VRC7 and OPLL modes you change bit 6 of $E000. 1 = VRC7 / 0 = OPLL :)

Currently there isn't a NSF-compatible application for this mode, but NES export of 0CC-FamiTracker (given modification) will adequately address it. :)

I'm not quite certain if the PowerPak NSF player will work with OPLL-mode VRC7 NSFs, but in theory they should if bit 6 of $E000 is cleared and OPLL code is driven through the VRC7 hardware-access registers. No additional modification of the NSF spec would be necessary for other non-NES/Famicom hardware players; just the emulation of the OPLL core. :)

*pokes HertzDevil in the rib with a boney finger*

did he deliberately make the opll incompatible with nsd.lib

hrm... I see what you mean. http://shaw.la.coocan.jp/nsdl/ that could have been an interesting way to do it. seems like bit 4 and 5 of $e000 is free. i'll talk to him.

also it is NSD.lib compatible, but not TNSx compatible. if bit 6 was set to 0 then the VRC7/OPLL would be silent.