Author Topic: No mapper emulation  (Read 3865 times)

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Offline melovictor

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No mapper emulation
« on: October 21, 2016, 09:30 PM »
Hi guys,

I am new here...

I was wondering...for the sake of perfect emulation accuracy, is someone aware of "hardware" emulation cartridges?

Let me explain...

Let's say we could have a real nes cartridge with a physical mapper (e.g. MMC3)  but capable of loading multiple games that use the same mapper.

So basically with 6 cartridges we could cover 80-90% of all the nes games with max precision.

What do you think? would it be possible? does it already exist?

Thanks,
Victor

Offline hunterk

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Re: No mapper emulation
« Reply #1 on: October 21, 2016, 11:07 PM »
You're basically describing a "repro". You have to reflash the E/EPROM/flash storage each time you want to change games and it cannibalizes an existing "donor" cart in the process of production.

Offline melovictor

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Re: No mapper emulation
« Reply #2 on: October 21, 2016, 11:20 PM »
You're basically describing a "repro". You have to reflash the E/EPROM/flash storage each time you want to change games and it cannibalizes an existing "donor" cart in the process of production.

But if you could store the roms in a SD card instead of eprom this wouldn't be a problem. So it would work like the everdrive(I have 2) but the mapper would be physically present in the cartridge. Because I think it is virtually impossible to physically fit all the popular mappers in one cartridge it would have to be spitted in many cartridges by mapper type.
To be 100% perfect each cartridge could hold all versions of that mapper (e.g.  MMC1A, MMC1B1, MMC1B2, and MMC1C.) if necessary...
My point is to use one mapper to play many roms without having to flash eprom like "repros"
This is just an idea that I had and seems very reasonable to me...

Offline butfluffy

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Re: No mapper emulation
« Reply #3 on: October 22, 2016, 03:33 AM »
it's an interesting idea, it would be cool if it would work as a passthrough cart which could be used with the n8 for more complex mappers like mmc5 allowing mmc5 games to be played perfectly with n8 and mmc5 passthrough cart.
 if this kind passthrough cart is feasible then one immediate problem that springs to mind would be functionality with front loaders, pass carts would work way better with top loaders. if i remember right there was some third party passthrough cart released for the nes front loader and it looked ugly as hell but it worked i guess. i can't remember what it was, maybe an import game player or a cheat cartridge or something like that.

Offline melovictor

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Re: No mapper emulation
« Reply #4 on: October 23, 2016, 11:45 PM »
it's an interesting idea, it would be cool if it would work as a passthrough cart which could be used with the n8 for more complex mappers like mmc5 allowing mmc5 games to be played perfectly with n8 and mmc5 passthrough cart.
 if this kind passthrough cart is feasible then one immediate problem that springs to mind would be functionality with front loaders, pass carts would work way better with top loaders. if i remember right there was some third party passthrough cart released for the nes front loader and it looked ugly as hell but it worked i guess. i can't remember what it was, maybe an import game player or a cheat cartridge or something like that.

I've never seem a passthrough cart with this intent.
But I think something should  be done in this direction because mapper software emulation has always been an issue.
I my opinion a everdrive n8 with original hardware mappers would be a hit. Games would run without glitches and alike. All games would work(with the appropriate mapper cart).
If I had the knowledge I'd make it myself.
Whatever just an ideia...

Offline thecavalry

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Re: No mapper emulation
« Reply #5 on: October 24, 2016, 10:59 AM »
So basically you want the N8...just not with an FPGA. The Everdrive basically does this through hardware emulation (FPGA).

Offline melovictor

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Re: No mapper emulation
« Reply #6 on: October 24, 2016, 04:34 PM »
So basically you want the N8...just not with an FPGA. The Everdrive basically does this through hardware emulation (FPGA).

Exactly! The N8 works decently well but it is far from being perfect. I want for example an Everdrive N8 MMC3 (the actual MMC3 chip) no FPGA for mapper emulation. Obviously only MMC3 games would work on this example. This must be quite an easy thing for people like krikzz to achieve. Would there be market for it?

Offline butfluffy

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Re: No mapper emulation
« Reply #7 on: October 24, 2016, 05:37 PM »
FPGA for mapper emulation is fine for the most part and any issues caused by mapper emulation with problematic games should be fixable with krikzz's OS updates.
 the improvements and bug fixing take time because krikzz is busy with real life and dedicating himself to all the everdrives OS updates and so on but for the most part the N8 is fine as it is.
 as i said, i like this idea for the really problematic mappers, the mmc5 for example, implementing full mmc5 support sounds like a nightmare of a job and if i had to purchase an addon mmc5 passthrough cart i would do so gladly.
 i don't like the idea of pasthrough carts for all or most mappers. there are way too many mappers and thats a lot of chips but for mmc5 and any other nightmare mappers it would be cool. 

Offline hunterk

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Re: No mapper emulation
« Reply #8 on: October 24, 2016, 05:46 PM »
There are some arcade loaders that work sort of like this. The Naomi loader uses as raspberry pi and some custom hardware to hook into a Naomi motherboard and load the data into it as if it were a native daughterboard and you can press buttons on the RPi to switch games. Likewise, the FDSStick and FDSEmu work similarly in that they hook in-line with a real FDS RAM adapter and just pass the disk's data to it as if it were a real drive, which makes for perfect audio (something that's a bit lacking on the N8).

My biggest problem with this approach for NES carts, though, is that you would have to sacrifice donor hardware, i.e. desoldering chips from actual carts and replacing them with the loader. Besides, the N8's MMC3 mapper emulation seems to be quite solid (it passes all of the MMC3 test ROMs I've thrown at it), and the only mappers it really has issues with are the one VRC7 game and a small handful of obscure MMC5 games (Castlevania 3, the one "big" MMC5 game, works well). In either case, you'll have to destroy an already rare and expensive game to produce the multicart.

There are folks that produce SuperFX multicarts that run all of the SFX games (including Star Fox 2) off of a single cart, which is really cool and a lot of SD2SNES owners have purchased these since that flash cart doesn't emulate the SFX chip. However, each multicart requires sacrificing a copy of Doom or Stunt Race FX, which are cheap and relatively plentiful right now but won't be forever.