Falsion repro schematics

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Fisher
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Falsion repro schematics

Post by Fisher » Mon Jul 20, 2020 6:25 pm

After I totally misunderstanding this tread, thinking the schematics were the same as Falsion I could think a little and end up with this:
Schematics
Schematics
And well, it works!
Sorry about the drawing, it was done on LibreOffice Draw, hope I've transcribed it correctly.

So, I have 3 questions:
1- The game don't run on my Phantom System Clone, It has the same problems I got with my pirate copy of Gradius, F-15, the Highway Star repro I've turned into this game and, of course, this game.
Before assembling it I tried the EPROM on my UNROM test board removing both the 74'161, the 74'132 and bridging CPU A14 to ROM A14, so it was mostly a NROM with CHR RAM. The game booted fine and I could even start it, but obviously it crashed as soon as the first enemy come close.
With this in mind I think I can discard the "ROM speed interfering with controller reads" thesis.
I also lifted the CPU D0 pin on the PPU and tried removing the controller's buffers before with no change, so now I just have no idea of what could be going on nor a nice logic analyser I could use to inspect it...
Could it be something related to the mapper or the way I've built it?

2- Does the Bubble Bobble's FDS conversion uses this exact same mapper or I need do modify it?

3- Can someone please recomend me a nice Linux friendly schematic drawing program?
I used to use Eagle, but somehow it become difficult for me to install on the laptop I'm currently using.

Tanks in advance.

Ice Man
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Re: Falsion repro schematics

Post by Ice Man » Tue Jul 21, 2020 12:25 am

3. Use KiCad.

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Fisher
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Re: Falsion repro schematics

Post by Fisher » Tue Jul 21, 2020 6:16 am

Thanks!
I'll try that.

I forgot to ask if a romhack for "fixing" Falsion's sound exists?
Since it uses the FDS extra channels, the music without it sounds a little "off", giving the sense that something is missing.
I googled and found nothing.

lidnariq
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Re: Falsion repro schematics

Post by lidnariq » Tue Jul 21, 2020 10:56 am

Most of the tracks use all six audio channels; there won't be a simple hack because it'd require rearranging each of the songs.

If you can find some other cheap tone generator it might be more possible to hack the result to use that.

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Fisher
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Re: Falsion repro schematics

Post by Fisher » Tue Jul 21, 2020 1:16 pm

Interesting.
Does a off-the-shelf similar to FDS audio generator exists?
I tried reading it's characteristics on the wiki, but I found it too complex for me to understand everything right now...
Maybe it's possible to hack a Namco 163 chip to it, but i would prefer some part I could get form old, discarded boards as with most of the ones I've been using.

Or learn music and try to make a "remix" of the tracks using the standard NES sound channels, but this option seems like a long way to go, since my musicall skills are next to non-existent.

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Fisher
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Re: Falsion repro schematics

Post by Fisher » Tue Jul 21, 2020 1:16 pm

Interesting.
Does a off-the-shelf similar to FDS audio generator exists?
I tried reading it's characteristics on the wiki, but I found it too complex for me to understand everything right now...
Maybe it's possible to hack a Namco 163 chip to it, but i would prefer some part I could get form old, discarded boards as with most of the ones I've been using.

Or learn music and try to make a "remix" of the tracks using the standard NES sound channels, but this option seems like a long way to go, since my musicall skills are next to non-existent.

lidnariq
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Re: Falsion repro schematics

Post by lidnariq » Tue Jul 21, 2020 2:54 pm

Rearranging things is often pretty mechanical, and you often don't need much of an ear for it. If you want an excuse to play around with Famitracker...

As far as I can tell, most of the generic off-the-shelf sound generators use a "divider" structure like the NES's internal registers (see: SN76489, AY-3-8910, misusing a 8254)
I don't know of all that many general-purpose sound generators that use the same "accumulator" structure that the FDS, 163, SNES, and C64's SID use. I'd probably start off by seeing what you can get your hands on.

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Fisher
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Re: Falsion repro schematics

Post by Fisher » Tue Jul 21, 2020 4:53 pm

Well, I need to check it out, but I have some "dead" SNESes wich I could get the sound chips if they're that similar to the FDS audio chips.
I think I still have a complete sound module from a dead snes, wich would be very easy to moiunt inside the cartrige.

I probably have some FM chips from old soundcards too, but AFAIK the FDS uses a kind of wave table so, they're probably useless in this case.

On the SNES with the onboard sound version, would be possible to cut the board and mount the sound part it inside the cartridge?
Guess it will depend much on the method I use to cut it.

lidnariq
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Re: Falsion repro schematics

Post by lidnariq » Tue Jul 21, 2020 5:35 pm

Fisher wrote:
Tue Jul 21, 2020 4:53 pm
Well, I need to check it out, but I have some "dead" SNESes wich I could get the sound chips if they're that similar to the FDS audio chips.
I think I still have a complete sound module from a dead snes, wich would be very easy to moiunt inside the cartrige.
They're not that similar. It's just the same "accumulator" pitch selector, instead of a "divider" or Yamaha's FM synthesizers' "octave+accumulator".

But the one huge advantage is that the S-SMP could translate between the data encoding used by the FDS and the encoding needed by the S-DSP. Of course... you'd also need to get this translating software into it.
AFAIK the FDS uses a kind of wave table so, they're probably useless in this case.
Depends entirely on how accurate you want the sound to be. Somewhere you're going to have to translate between the original registers and whatever you want instead - there's definitely no 100% binary-compatible option available - so maybe that's at build time, or maybe there's an emulator at run time.
On the SNES with the onboard sound version, would be possible to cut the board and mount the sound part it inside the cartridge?
As far as I know, yes, you should be able to cut away the parts that are not in the discrete SPC700 module and be left with something that acts like one.

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Fisher
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Re: Falsion repro schematics

Post by Fisher » Wed Jul 22, 2020 8:08 pm

Wow!
There are so many possibilities!
I would like something simple, that sounds OK, preferably don't need to hack the rom and could be done with some discrete components.
But looks like it doesn't exist.
Maybe I could try something interesting if I learn fpga...

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