Questions about modern NES multicarts

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OneCrudeDude
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Questions about modern NES multicarts

Post by OneCrudeDude » Mon Mar 12, 2018 2:06 am

This is probably the best board for it, if it's not correct feel free to move it.

About a week ago, I purchased a multicart from someone on Etsy, this one in fact.

https://www.etsy.com/listing/458208774/ ... ome_feat_2

And I've noticed that it has a wide variety of mapper support, unlike multicarts of old that consisted mostly of NROM titles. It even has support for battery saved games like Zelda or Crystalis, more on those later. I'd open the cartridge myself, one of the screwholes is covered by date sticker which may also act as a warranty void when removed, but I'm having some problems with a few games (namely Ikari III = screen jitters when scrolling vertically, Over Horizon = background goes black every fourth BG animation frame), and I wanted to see if I could get a replacement, perhaps he flashed a bad ROM to the cartridge. So this is where my questions come in.

Are these multicarts "home made", or are they sourced from somewhere like China? Considering how many titles retain the Nintendo license, these may be home made. Are there any tools they used to flash these carts, and what kind of boards do they use? Where did they get the shells for them, I remember RetroUSB used to sell some swanky translucent shells but haven't carried them in years. And finally, this cartridge has 20 games with battery backup, but you can only save progress for one game at a time. Is this a limitation of the NES and how it works, or is it possible to have each game retain its data without being overwritten by another?

Sorry for the big, wordy thread, but I'm curious about these. I have a morbid curiosity and see if I can get into this business myself, that's the main reason I'm asking. I understand this is a gray area, if not outright illegal, so my apologies.

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FrankenGraphics
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Re: Questions about modern NES multicarts

Post by FrankenGraphics » Mon Mar 12, 2018 2:29 am

It's 99% to be one of the mmc3-like pirate multicarts anyone can order from aliExpress with custom stickers and a higher price tag.

You should avoid using them, because they will hurt your console by gradually wearing it down with excessive currents.

https://db-electronics.ca/2017/07/05/the-dangers-of-3-3v-flash-in-retro-consoles/

tl;dr quote from that article:
Prolonged use of components outside of their specified tolerances inevitably leads to failure. On the console side, the stress is excessive current output on digital outputs when driving a logic high. On the cartridge side, the stress is excessive heat dissipation due to conduction of the clamping diodes. I have already heard from several friends that their NES consoles have died most likely due to their admittedly heavy use of cheap multicarts. These are particularly bad. I would avoid these like the plague
If you want to open it up for the sake of knowing for sure, you could, but i'd return it and try to get my money back and report that shop for selling pirate software afterwards.

Selling bootlegs is not a gray area, it's outright wrong. But what's worse these guys and their customers don't know they're wrecking antique consoles. Don't go this path.

As for the question about battery backed WRAM, it's not as much a limitation of the NES as it is a limitation of the mapper + how the games were written. It wasn't built for mapping WRAM for several games, and each one of them will overwrite the same WRAM space.
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Fisher
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Re: Questions about modern NES multicarts

Post by Fisher » Mon Mar 12, 2018 3:53 am

OneCrudeDude wrote: see if I can get into this business myself
If you're planning to enter this business, I strongly suggest you to talk with Infinite Nes Lives.
He produces high quality PCBs, shells and most of the things you'll need.
Just be careful about what you'll be doing, or you'll have a chance to get legal troubles. :wink:

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OneCrudeDude
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Re: Questions about modern NES multicarts

Post by OneCrudeDude » Mon Mar 12, 2018 10:21 pm

FrankenGraphics wrote: You should avoid using them, because they will hurt your console by gradually wearing it down with excessive currents.
I actually just got done reading about that in another thread. That's pretty wild, I never knew that was such a thing until now. At least I know they use a cheap Chinese PCB, and there's an alternative if what Fisher said is correct.
Fisher wrote: If you're planning to enter this business, I strongly suggest you to talk with Infinite Nes Lives.
That also reminds me of there being a program that allowed you to create your own multicart menu, though my googling seems to bring up much more limited ones. I wonder what these modern multicarts used, since they have a huge mishmash of NROM, UNROM, and MMC3 games. I like the idea of making a "Ninja Collection", with a graphic of Joe Shinobi looking around, featuring all the NES/Famicom games with ninjas in them, for example, so for the sake of this thread, I'd like to know for research and entertainment purposes. The multicart I have features some simple graphics of a hill with trees and Link looking upwards, and some others have more elaborate screens, such as the Unchained Melody Multicarts. But first, let's start smaller, how are these 'games' made in the first place?

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Re: Questions about modern NES multicarts

Post by rainwarrior » Mon Mar 12, 2018 10:44 pm

If you look at the frequency of mappers used:
http://bootgod.dyndns.org:7777/stats.php?page=6

You can cover a lot of games with a multicart that only supports MMC1 or MMC3. More than half of them if you support both. The difference between a mapper and its multicart version is usually just one or two more registers to increase the banking ranges. You kinda get NROM as a free additional target with any mapper anyway.

1 mapper: 28% (MMC1)
2 mappers: 52% (+MMC3)
3 mappers: 63% (+UxROM)
4 mappers: 74% (+NROM)
5 mappers: 80% (+CNROM)

If you can afford to play the games for a bit and find their banking code, you can even hack a lot of simpler mapper games to use MMC3, and cut back on your mapper implementation that way. Depends on whether mapper complexity or debugging time is more precious to you. The debugging/hacking part is way easier these days than it used to be.

Making a wide variety of games support battery backed save is probably as simple as throwing WRAM into its usual position at $6000 and battery backing it. That's where almost all battery save games put their data, and for most games that don't use WRAM it's a harmless addition. If you want to be really nice you can bankswitch a larger RAM so that each game has a separate 8k page. If you want to be cheap just live with changing games resulting in wiping your saves.

(All that said, I hope you're doing something more interesting than just trying to sell pirate multicarts. :P I'm not here to stop you, though.)

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OneCrudeDude
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Re: Questions about modern NES multicarts

Post by OneCrudeDude » Tue Mar 13, 2018 7:41 pm

That makes sense, since I read somewhere that some multicarts have an inflated PRG ROM chip and I think a CHR RAM chip, so that they throw the graphics they need whenever they wanted to as opposed to having a massive CHR and PRG chip. But I'm more curious as to how the software is put together, at least today. Do they use a program to merge them together, or are the ROMs "stitched" together, with a selection screen being what "separates" the games from one another? Considering the number of variations of multicarts (such as a cartoon themed one), there must be a tool to jam all these games together.

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Re: Questions about modern NES multicarts

Post by tepples » Tue Mar 13, 2018 9:23 pm

The Action 53 series were built with a tool that I wrote that takes a list of ROMs and descriptions, compresses the CHR ROM data of those games that have it, and squeezes it into various places, such as extra banks automatically allocated for that purpose or unused areas in other games' PRG ROM. This can be the unused half of an NROM-128 or even an address range marked in the game's entry in the collection's config file as unused.

Whether it's done automatically with a tool or manually with a hex editor, there's usually a concept of "outer bank". The multicart mapper has two sets of registers: one for the mapper that the game uses, which controls the lower address lines, and a separate set that controls the higher address lines.

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Re: Questions about modern NES multicarts

Post by OneCrudeDude » Wed Mar 14, 2018 2:11 am

Ah, I see. So they are made with tools then. I was always curious about that, thank you.

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Re: Questions about modern NES multicarts

Post by FrankenGraphics » Wed Mar 14, 2018 3:47 am

You can also do it with any hex editor, or using the pretty powerful directives in ca65 (you can .incbin a specified range of a binary, patch in something, then .incbin some other range of the same binary).
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Re: Questions about modern NES multicarts

Post by koitsu » Wed Mar 14, 2018 10:31 am

My belief is that it simply varies. There is no "magical universal tool" that all these Asian companies are using to churn out stuff like this. There's going to be variance. Some may have made something themselves. Others might be tacking it together manually. If you look at the history of pirate multicarts (e.g. those "1000 in 1" carts), many of them are just hobbled together -- I'm talking about the software -- in a very unorganised "get this stuff shipped ASAP" way.

There may be open tools now -- like the one tepples wrote -- but there weren't any that I know of up until then. So, back to my point: every group (company, contracted group, whatever) did this differently. But if someone was to sit down and compare them all (re: dump old multicart games), I would bet you would find some similarities in code between them all. Does this indicate a "common tool" used? IT DOES NOT. What's easily overlooked/forgotten/whatever: this is a pirate market demographic. In that demographic today -- just as it was in the 80s -- the usual approach is steal from others. A 500-in-1 multicart just came on the streets in Guangzhou? "Hey Li, go buy a copy, dump it, disassemble it, and figure out how it works + let's use it to make our own multicart." This was incredibly commonplace then, and it's still commonplace now. I suppose having cultural familiarity with some demographics (ex. China, Taiwan, Hong Kong, Korea) helps, because this tends to be a deeply ingrained societal thing in tech markets there. As a Mandarin speaker who studied Chinese history as well, I assure you that my comment is not driven by bigotry -- this really is a common approach/tactic.

So, in short, to conclude "a common tool was used" is, respectfully of course (honest!), ignorant. It's more likely that these are hobbled together quickly, probably based on existing stolen mappers/carts and reverse-engineered code equally pirated/stolen.

And to be clear: I'm not talking about the commercial games which are pirated, I'm talking about the multicart mapper (the hardware) and the code associated with the menuing systems and so on. There are probably thousands of these things at this point, no joke.

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