Questions about flash chips: Neo SD vs. bootlegs.

[NeoNovice]

So I’ve bought a couple of bootleg MVS carts for games that are prohibitively expensive. They’re the ones with the short, red boards and flash chips from China. And it seems the consensus online is that voltage fluctuation will eventually cause the flash chips in them to die.

If this happens, so be it. I’m out like 40 bucks. But what about the Neo SD? It looks like that uses the exact same kind of flash chips. Wouldn’t the voltage have the same effect on that? And if it did, I’d be out like $600!

How do the components of the Neo SD differ from these bootleg carts? What about newer homebrew MVS games or those insanely rare and expensive NG.Dev.Team games? Aren’t they all using the same kind of chips?

 

[thegreathopper]

I don’t think the chips are the issue it’s the voltage feeding those chips.

The cheap Chinese carts have bad or no voltage regulation which could.. cause them to stop working.

 

[leonk]

In the 90's, most chips ran at 5V. Modern flash chips run at 3.3V or less. To overly simplify it, what this means is that when a modern flash chip sends a "1" to the Neo Geo system, it might interpret it wrong. It might think the "1" is really a "0". There's of course other potential issues, like a flash chip acting as a voltage sink for all the 5V components in the console. What will die is the Neo Geo - not the cart. But I've yet heard of this happening, and we've had multicarts for over a decade.

Properly designed multicarts (like NeoSD, EverDrive, CD emulators, etc) don't plug directly into the data bus. They use what's known as voltage level translators that sit between the flash chips and the slot and translate between 3.3V and 5V. The flash cart thinks it's in a 3.3V console; the console thinks it's got a 5V cart. Many problems go away. Only flaw with this system is cost; the chips cost $. NeoSD has them, China bootlegs don't.

FWIW. Bumping the voltage the chips run at is NOT enough. All you're doing is running a 3.3V chip at higher voltage (some aren't rated for that) without tackling the true issue - the data/address lines are still at 3.3V on a 5V bus. The translators have all the address/data lines go through them.

 

[NeoNovice]

In the 90's, most chips ran at 5V. Modern flash chips run at 3.3V or less. To overly simplify it, what this means is that when a modern flash chip sends a "1" to the Neo Geo system, it might interpret it wrong. It might think the "1" is really a "0". There's of course other potential issues, like a flash chip acting as a voltage sink for all the 5V components in the console. What will die is the Neo Geo - not the cart. But I've yet heard of this happening, and we've had multicarts for over a decade.

Properly designed multicarts (like NeoSD, EverDrive, CD emulators, etc) don't plug directly into the data bus. They use what's known as voltage level translators that sit between the flash chips and the slot and translate between 3.3V and 5V. The flash cart thinks it's in a 3.3V console; the console thinks it's got a 5V cart. Many problems go away. Only flaw with this system is cost; the chips cost $. NeoSD has them, China bootlegs don't.

FWIW. Bumping the voltage the chips run at is NOT enough. All you're doing is running a 3.3V chip at higher voltage (some aren't rated for that) without tackling the true issue - the data/address lines are still at 3.3V on a 5V bus. The translators have all the address/data lines go through them.

Wow, this is super informative. Thank you!