Quote:
I recall an old Genesis Flash cart schematics that used 3.3v Flash, and instead of level shifter ICs it used a pile of resistors, one per every address and data line.
I think that's the example HardwareMan used when I asked him why his infinitenes flash cart used 'limiting resistors' vice level shifters. 'input/output limiting resistors' don't actually solve the problem. You can use a voltage divider on inputs, but for bidirectional data lines you can't use level shifters. Putting a single resistor in series doesn't actually change the voltage present at the pin. While you are effectively creating a voltage divider with the ESD diodes and the input resistor, you're still exceeding maximum chip ratings...
Level shifters are crazy cheap and common. I understand why 'hackers' don't bother with them because you can't put them on donor carts very easily. But for new designs/PCBs we're only talking about 30-50cents. Don't be lazy/skimpy, Just use em!!! Plus they are easier for assembly compared to using a TON of resistors that don't even fully resolve the issue.
MottZilla wrote:
So though people that have been putting this 29L3211 into SA-1 and SDD1 cartridge will eventually see the chip fail?
And could this really damage the SNES itself?
I wouldn't expect it to damage the SNES/console. But it's hard to say exactly what will happen when things fail. Before failure you'd be drawing some extra current on the address and data lines, but the console can *probably* handle that okay, I've never measured what that current is, nor do I know the ratings of the CPU's.
But once the ESD diode fails, all bets are off. My guess is they'll shoot-trough and short to Vcc/Gnd but that's just speculation. Because it'll stop working you'll probably stop continually putting stress on the console, and keep from causing permanent damage but it's still uncertain what will happen to these 20+ year old line drivers inside your CPU...