Authentic FDS RP2C33 Audio for NSFs

So I've been experimenting with original hardware recordings of my NSF covers, and I've been wondering...

Is it feasible to either:

a) Create a custom cartridge with FDS audio implemented?

or

b) Create a custom disk to play NSFs from on an FDS?

I would really like to use authentic expansion chips in these recordings rather than rely on emulation. I think I might avoid FDS if I can't get someone to do accurate recordings in the near future.

Totally doable. Just somewhat obnoxious, and NSF's bankswitching style is particularly obtuse with the FDS (which provides only 32KiB flat RAM from $6000-$DFFF and BIOS from $E000-$FFFF).

There's a person in Japan who's explicitly made hardware players for NSFs: the TNS-HFC4 and HFX4 are overkill, but they do explicitly support the FDS base (while the TNS-HFC3 is claimed not to).

Making an FDS image out of an unbanked NSF shouldn't be too awful: you'd need to provide it with up to 32 KiB of PRG to upload to RAM, and deal with the bootloader. A little more involved than vegaplay, but not tremendously.

It's possible to do both those things, yes.

My own solution was to make a cartridge extension connector for my NES and plugged an FDS into that, and then used CopyNES to stream logged writes from an NSF to it. In this situation the audio mix level of the FDS is arbitrary, but at least all the sound producers are the real thing.

Wow. So I would, like, need to attach the games to the dongle? (I already have Lagrange Point and Rolling Thunder, so I guess I'm halfway there? I don't have plans to do any Sunsoft 5B yet so I won't need Gimmick!)

Question with that thing: can you combine expansion audio? Not that I'm planning to do that.


I take it there are variations in audio levels among different FDS releases? (Like the Sharp Twin, etc.) I don't mind too much as long as it's not obviously way off. (I was told the audio in my NES mod was low but I think it sounds alright).

Anyway, I don't plan on getting a Disk System anytime soon, so I'd be up for someone recording everything for me.

Take a look at this monster: http://www2s.biglobe.ne.jp/~tns/nr26730221.html



The mix level is pretty variable. There's a a bit of variation from NES to NES, Famicom to Famicom of how the two 2A03 audio pins get mixed, then for expansion audio carts there is also variation from cart to cart. So, between these two factors it's hard to get a bead on what the levels "should" be (though I tried to gather a little bit of consensus through multiple recordings across different hardware when tuning NSFPlay). This is not to mention that different games that use the same expansion audio are often mixed at different levels intentionally, having a different mixing spec on a per-game basis, espeically among the various N163 games.

From what I've heard the FDS audio for the Famicom Twin units is generally way too loud compared to the original Famicom + FDS combo.

Wait, so FDS sound can be built right in? Hmm...



I figured. But from what I can understand from this page you can have volume control?

At the very least, you cleared up the issue I was having. Does anyone here have this?

Yes, I believe the TNS-HFC carts have a volume control of some kind; from what I understand they don't send the audio back to the Famicom, but instead have an output jack on the board. I've never seen one firsthand though, and they don't ship outside of Japan.

I put a volume control on my NES audio mod, myself. It's very handy when trying to balance the expansion carts.

By the way, does your setup have its own output jack?

My NES has RCA outs, and my Famicom is AV-modded with RCA outs, so yes.

The reason the TNS-HFC doesn't send it back through the cart is that the standard Famicom only has RF out.

But don't you still get a hum? I thought going straight from the board would prevent any interference.

Here's a recording I did from my NES RCA Audio jack (sounds like there's slight noise):
http://www.youtube.com/watch?v=bsERbZj-IKk

The NES unfortunately has a problem where its audio and video signals are insufficiently decoupled, for various reasons. You might find this thread useful.

The hum isn't from the jack, it's coming from the NES/Famicom and is part of the 2A03's audio signal. Placing a jack on the Famicom cartridge won't help with this.

You could disconnecting the 2A03 audio and record the expansion only. It would get rid of the hum from the 2A03 source, but obviously you don't get the 2A03 sound either. It depends where you have use for the expansion sound; if you're hoping for an authentic hardware recording you're going to need a 2A03 (with authentic hum) in there.

I have heard that making your NSF player display the forbidden beyond-black colour in the background can reduce the hum (since it is largely crosstalk from the PPU signal).

If the hum is from crosstalk with the PPU, then there won't be such hum in a standalone module with no PPU.

Yeah, actually, disconnecting the PPU entirely could help!

Oy, you guys aware you can mask/shadow away the memory from the FDS RAM adapter and only expose the I/O registers for the sound and disk hardware???

I suppose that's how the Front Far East copiers which used FDS as basis worked...

It really seems an oversight to me that the FDS doesn't have a built in register bit to write protect its RAM.

Unless the FDS engineers expected that game programmers would use C64 or MSX style coding where all memory is writable.

They forced that. I'm saying it could have been an option for very little extra silicon.