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Hi All,
I'm trying to find a way to build an .NES from a FT VRC7.NSF. I've run across a hack to Vegaplay by Grapeshot but I need some advice.
viewtopic.php?f=3&t=9102&p=96897#p96897
I have a simple test FT 0.4.3 song that uses VRC7 and 2A03, no bank switching, less then 10K. I export to .NSF (FT doesn't export exp chip to .NES). Using Nestopia the NSF plays fine.
I follow the the procedure for Vegaplay, getting the Load, Init and Play addys. Edit the vegaplay.asm, strip the header out of the .NSF file and compile. The resultant .NES NROM plays the 2A03 fine. Now I change the iNES header to Mapper 85 and Nestopia chokes on it; blank screen, no sound but no error message. Also tried Nintendulator with the same result. The two Header bytes @ offset 06 and 07, from $00 $00 to $50 $50.
When I load up one of Grapeshot's VRC7 vegaplay NES', it plays fine. The post I ran across was 1 1/2 yrs old and seems he was using FT < ver 0.3.8 so I tried the build with FT 0.4.0 but this didn't help. Do you think I need to revert to an even earlier ver? but I need HW VRC7 compatibility which was fixed as of 0.3.8.
Any ideas what went wrong? Am I missing a setting in FT?
Yogi
EDIT fixed title

How big is the resulting .nes file? Not sure how the emu will handle files smaller than 32KB. You'll want to ensure that all code ends up in the fixed bank of prg rom $E000-FFFF (8KB). If it's already 32KB, but required data is outside of $E000-FFFF the emu probably isn't starting up with the banks initialized as you need them to be. You'll have to initialize the VRC7 prg bank select registers to ensure that all necessary data/code ends up in the correct banks.

infiniteneslives wrote:How big is the resulting .nes file? Not sure how the emu will handle files smaller than 32KB. You'll want to ensure that all code ends up in the fixed bank of prg rom $E000-FFFF (8KB). If it's already 32KB, but required data is outside of $E000-FFFF the emu probably isn't starting up with the banks initialized as you need them to be. You'll have to initialize the VRC7 prg bank select registers to ensure that all necessary data/code ends up in the correct banks.

Vegaplay builds a 41K NES, and like I said the NSF data is <10K in the PRG space. The weird thing is: only changing the mapper bytes in the header fouls it up. With no NSF bank switching going on it shouldn't make a difference, at least in my mind
Don't know if I'm fighting a EMU problem or a FT issue.
I'll add an edit to vegaplay for the banking regs; but the older Grapeshot NES didn't seem to need that?!? He did have a modded vegaplay.asm for MMC5 that did this, so may be that's the problem.
Yogi

All the mappers with expansion audio require initializing their banking registers, while a plain 2A03 song won't. (Well, won't unless it's too large for an unbanked NSF)

lidnariq wrote:All the mappers with expansion audio require initializing their banking registers, while a plain 2A03 song won't. (Well, won't unless it's too large for an unbanked NSF)

What is causing me the most confusion is the fact that the grapeshot VRC7 NES plays.
I think this is Grapeshot's youtube vid
http://www.youtube.com/watch?v=DQtR5sbADt8
He described only changing the Mapper bytes in the iNES header.
Yogi
EDIT- Here is one of Grapshot's .NES, one has the mapper set to 0, the other has it set to 85. Song 4 Has both 2A03 and VRC7 notes. Not much of a test, as I started with the VRC and downgraded to NROM.
So IDK

There are only two possible explanations for that video.

A: All of the code and data is inside the fixed bank; there is no need to initialize the mapper because the fixed bank is already initialized at power-on.

B: It only works on FCEUX, because FCEUX happened to map things the way the ROM was expecting. It will crash in most other emulators because the mapper is not initialized.

Your ROM does not work because you aren't initializing the mapper.

OK, there's two problems here. First of all, Famitracker 0.4 doesn't export all NSFs with a load address of 0x8000, instead it puts the load address somewhere in the 2nd or 3rd 8k. I'm not sure why this was changed, but it leads to the second issue, which is that FCEUX maps the VRC6 banks differently than Nestopia or Nintendulator do at startup, but all 3 map the first and last banks in the same place, it's the second and third that are different.

So the result is: a NSF made by Famitracker 0.38 and compiled by Vegaplay with only the mapper bytes changed will work properly in all 3 emulators if it's less than 8k, but if it's larger it only works in FCEUX (So my previous NES files only worked coincidentally.) A NSF made by Famitracker 0.4 series then compiled by Vegaplay will only work in FCEUX, regardless of size. I'm going to write some init code for the mapper to fix this, but it'll take me a bit to test it.

Also, does anyone know if the actual initial values for the VRC7 have been tested by anyone? It isn't listed on the wiki.

Nestopia initializes VRC7 on powerup as: Or, translated, bank 0 for the first three 8KiB slots and fixed to the last bank for the uppermost one.

But note that it doesn't reset this on reboot.

So, in any case, a VRC7 NES file that only uses the first and last 8KiB will work right in Nestopia. (and presumably on hardware).

FCEUX (2.2.1) doesn't intentionally initialize anything at all. On powerup, the preg array isn't initialized in code, so it instead falls back to the bit where global variables are initialized to 0. It sure looks to me like it should be the same as Nestopia...

Here's what you need to add to your vegaplay.asm file to make things consistent on all emulators.
Add it right after the "BNE ClearMemory" line, and your ROM should work in all emulators and the real hardware.

Nintendulator sets bank 0 to the second bank in the ROM, bank 1 to the first, and bank 2 to the second to last bank, for some reason.

@ Grapeshot Thank you very much for weighing in here. You cleared up much of my confusion. I did see that FT 4.0 was loading to $A64A but did not know it was causing the issue.
Thank you for the vegaplay patch, very cool of you.
Yogi

I guess I should finally make a new version of that Vegaplay special chip package, even if I don't really need it anymore since I implemented NSF support in my own emulator.

Grapeshot wrote:I guess I should finally make a new version of that Vegaplay special chip package, even if I don't really need it anymore since I implemented NSF support in my own emulator.

That would be cool.
Just re built my test ROM, works great. Thank you again!
A Plus for the insight on setting the VRC7 mapper, the wiki was a not clear for me.
Yogi

Something that may make this easier:

FamiTracker has an ASM export option in the NSF export dialog. You can use this in combination with the FamiTracker NSF driver source to rebuild your music at whatever address you need. (You can also make any necessary modifications for banking, etc. this way.)

rainwarrior wrote:Something that may make this easier:

FamiTracker has an ASM export option in the NSF export dialog. You can use this in combination with the FamiTracker NSF driver source to rebuild your music at whatever address you need. (You can also make any necessary modifications for banking, etc. this way.)

Grapeshot's register patch fixed the immediate problem I think.
But can you point me to any relevant docs on the asm export. I exported and read through the code but I will need many more passes over the code to understand it well enough to use it ATM.
What would you say is a viable location for the player code? vegaplay loads it's self into the top 2K of the PRG rom which isn't too bad but there is no guarantee that a NSF wouldn't be mapped into that space. It would result in an unplayable NFS?
I was going through Loopy's PowerPak NSF source a bit and it loads low, somewhere around $40?? Which is safe but complicates mapping.
I guess I'm wondering what a reasonable ROM size would be for the basic Play/driver and where to put it. Looking at the vegaplay code, Load and Init aren't very big and the Play is a simple call to the nsf play address driven by the NMI. So the bare bones seem very slight. I'm just a bad judge; don't know what I don't know.
Yogi

The FamiTracker driver is about 5.5k of data, as I recall. You can locate it anywhere you like if you build it from source. If you need to bankswitch DPCM, you probably want to keep it out of $C000-DFFF, but other than that there's no good or bad place for it; just depends on your other needs. The ASM or BIN export is just a block of music data, separate from the driver. It can also be located anywhere you like.

The only documentation for it is included with the driver source itself, though I did write this guide a long time ago: http://famitracker.com/forum/posts.php?page=1&id=3681