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PostPosted: Thu Jan 12, 2017 7:14 am 
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Should I stop using them considering the risks?

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PostPosted: Thu Jan 12, 2017 9:55 am 
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Hardly.

With how small the current is running between the cart and the system I'd hardly expect any catastrophic failure as a result of that. Unless they're running those 3V chips at 5V, and not using a voltage regulator, in which case I'd be a lot more concerned.


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PostPosted: Thu Jan 12, 2017 3:12 pm 
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If the only risk is ruining the carts, not using them just means you lose the cartridges sooner than if you waited for them to fail, but either way the outcome is that you end up without the cartridges...


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PostPosted: Thu Jan 12, 2017 9:05 pm 
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If the chip fails faster when using 5V, either it would fail immediately or over time.

Clearly, there's no immediate failure when using the cartridge normally. I believe the EMS cart has a voltage regulator. I know the bootleg carts don't most of them time. What I've found is that while you can read from the bootleg carts, you can't write to the flash while the supply voltage is 5V. A crude way of dealing with that is to add a diode across the supply line, which some of these carts helpfully include a pad for on the board. The diode drop just barely brings the voltage below the absolute maximum rating, and you can flash the flash chip.

Then there's long term use. I think the CMOS output drivers couldn't care less about the supply voltage. However, a read operation in a flash chip is ever so slightly destructive to the data, because it depletes the charge in the floating gate of the cell. This is true for flash chips under all conditions regardless of voltage conditions. It's possible that using a 5V supply makes that problems slightly worse. But you're still probably looking at many years of data retention.

All in all, I wouldn't worry too much.

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PostPosted: Thu Jan 12, 2017 10:01 pm 
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nitro2k01 wrote:
However, a read operation in a flash chip is ever so slightly destructive to the data, because it depletes the charge in the floating gate of the cell. This is true for flash chips under all conditions regardless of voltage conditions.
I'm about 95% certain that is simply untrue. All of the sources I have seen have indicated that the process by which the floating gate discharges is a function of temperature, time, and (if relevant) radiation, not what external voltages that are within the specified operating parameters.

A kinda interesting tangent, from this 23-year-old paper, is that the floating gate changes the threshold voltage for the cell. So an "off" cell run at too high of a supply voltage might actually look slightly "on", superlinearly increasing power consumption. (Look at figures 5, 10, and 11)


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PostPosted: Fri Jan 13, 2017 8:08 am 
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lidnariq wrote:
nitro2k01 wrote:
However, a read operation in a flash chip is ever so slightly destructive to the data, because it depletes the charge in the floating gate of the cell. This is true for flash chips under all conditions regardless of voltage conditions.
I'm about 95% certain that is simply untrue. All of the sources I have seen have indicated that the process by which the floating gate discharges is a function of temperature, time, and (if relevant) radiation, not what external voltages that are within the specified operating parameters.

A kinda interesting tangent, from this 23-year-old paper, is that the floating gate changes the threshold voltage for the cell. So an "off" cell run at too high of a supply voltage might actually look slightly "on", superlinearly increasing power consumption. (Look at figures 5, 10, and 11)


But wait I remember you saying this. viewtopic.php?f=12&t=13471#p158810

lidnariq wrote:
Using a 3V IC on a 5V system will stress both the IC's overvoltage protection diodes and the SNES's address/data bus drivers.

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PostPosted: Fri Jan 13, 2017 11:59 am 
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Using a 3V IC, supplied by 3V, in a 5V system, without current limiting... that will stress the driver and the overvoltage protection diodes. In the case of CMOS systems (like the GB and SNES), that's definitely a problem.

(For NMOS systems like the NES and SMS, it maybe might not, because NMOS pullups are just not very good at things)


For a 3V IC, supplied by 5V, that will cause a whole different set of weird failure modes, but at the beginning, they "ought" to be limited to destroying the 3V peripheral. (Once the 3V peripheral is sufficiently damaged it could become a short, then damaging the 5V driver).

One of the weird failure modes is what I'm referring to in my tangent related to that PDF: bits that were programmed may read as not, randomly.


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PostPosted: Sat Jan 14, 2017 10:15 am 
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Well, I have two answers so far: "It'll break your Game Boy" and "Sure, go for it".

Which one is correct? The Chinese bootlegs have a gloptop mapper, a 3V ROM chip, and a RAM chip.

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PostPosted: Sat Jan 14, 2017 6:25 pm 
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BlockOutGuy wrote:
Well, I have two answers so far: "It'll break your Game Boy" and "Sure, go for it".

Which one is correct? The Chinese bootlegs have a gloptop mapper, a 3V ROM chip, and a RAM chip.

As lidnariq explained, the difference is whether it's a 3V chip fed a 3V supply voltage or a 3V chip fed a 5V supply voltage. Different scenarios.

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PostPosted: Sun Jan 15, 2017 3:54 am 
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nitro2k01 wrote:
BlockOutGuy wrote:
Well, I have two answers so far: "It'll break your Game Boy" and "Sure, go for it".

Which one is correct? The Chinese bootlegs have a gloptop mapper, a 3V ROM chip, and a RAM chip.

As lidnariq explained, the difference is whether it's a 3V chip fed a 3V supply voltage or a 3V chip fed a 5V supply voltage. Different scenarios.


Are my carts in the "both'll die" camp? or the "only the cart'll die" camp?

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PostPosted: Sun Jan 15, 2017 10:05 am 
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If you don't see any small part that looks like this, I'd bet it's in "3V part will eventually die, but no damage will happen to the system in the mean time"


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PostPosted: Mon Jan 16, 2017 3:12 am 
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lidnariq wrote:
If you don't see any small part that looks like this, I'd bet it's in "3V part will eventually die, but no damage will happen to the system in the mean time"


Yeah, it's just the glop, the ROM, RAM, and slightly-too-big-for-the-case savebattery. Board looks not unlike this (pic by "Koji Kendo"): http://i.imgur.com/Fu8ca0x.jpg

On the other hand, this one is no good: http://store.kitsch-bent.com/product/ki ... t-bennvenn

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PostPosted: Mon Jan 16, 2017 9:08 am 
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Those pirate carts are of the type where the cartridge might die eventually. EMS64 is probably of the other type. I've heard people complain that it drains the Gameboy's battery, and is causing crashes/power failures, especially on Gameboy Pocket which is using AAA batteries instead of AA. Leakage through the protection diodes could be a likely cause. I haven't heard about permanent damage to the CPU from using an EMS64 cart, though.

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PostPosted: Mon Jan 16, 2017 9:49 am 
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nitro2k01 wrote:
EMS64 is probably of the other type. I've heard people complain that it drains the Gameboy's battery, and is causing crashes/power failures, especially on Gameboy Pocket which is using AAA batteries instead of AA. Leakage through the protection diodes could be a likely cause. I haven't heard about permanent damage to the CPU from using an EMS64 cart, though.

Who wants to buy an EMS64 cheap? :mrgreen:

Seriously, I've been meaning to get rid of that POS (which I've never used, BTW, I was always putting it off because setting it up sounded like a chore) ever since I bought a GB Everdrive a couple years ago.


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