Is the NES chr and prg rom on seperate data bus, prg for cpu and chr for ppu? and bankswitching refers to the prg memory locations?

Is chr memory only for ppu data, is it possible to use chr for dmc samples?

Is there an address area for directly selecting the ppu memory? - I saw another thread mention accessing directly over storing to 2006-2007? - but I'm not sure about the address range,

Also sidenote, half of mck driver is for n106, and fds routines, I suppose shaving it down having a strictly 2a03 version could free up for extra song data, although I'm not sure why mck still writes data to fill space, is there some kind of preset size a nes has to be?

cool, thanks much,

also I've been brainstorming more on the layout and internal dataformats for a sequencing app/rom, for music, well continuing on anyhow, from way back , but at least now I have a better understanding so I can try some basic things, honestly I kind of like more of a freeform approach rather than a normal tracked approach, like having a macro/array grouping but being able to apply it to different things, rather than have seperate memory for each area, thinking about ways to compress the info and keep it flexible

anyhow I'll gather my scribblings on the music rom, post in another thread here, thanks