So, would it be possible to make a pass-through device (I am thinking about the Genesis specifically) that steps the 5V to the 3.3V and then passes that to the Everdrive to use? Or are there other parts of the Everdrive that specifically need the 5V and wouldn't work with a 3.3V instead.
As a matter of practicality, since this would only be needed to fix a shitty product more poorly made than itself, I don't see this happening. I guess it would depend on the system in question.
The reason he speaks of level modifiers instead of regulators or current limiting resistors is because it's really a much more delicate job.
(I really need to say, I am not an expert on electronics or semiconductors of this nature. My professional electronic experience is mostly automotive and I sorta know a few things about audio but that's about it. I think I understand the issue well enough to say this though.)
So let's say you have a 5V bus and a 3.3V flash cart. What happens?
The 3.3V chip would be overpowered. This is no problem. You can put a reg in there or even just a resistor, if you know all the hardware variations, since that actually would work for powering the chip. This has been done with most of these carts according to the video.
However, carts have lots of pins. The Neo has 256! Many are unused but regardless, there is more than just powering the chip to take care of. All the data lines on the bus (cart slot) are designed to send and receive at 5V.
Let's say, for example, that you had just one data out and one data in. They could be connected to the CPU, the RAM, the sound chip, some serial bus, whatever. Just consider that one is in and one is out.
So the data out on the bus is hooked to a data in on the flash. The flash basically watches that pin for a square wave, bits, like knocking on a door. This works fine, the flash will see the knocking on the door, but it will be REALLY LOUD, like that mouth breather who slams the door of your car so hard it shakes the entire parking lot. Now, if this were something a motor being overpowered it would just spin faster and make more heat and maybe waste it's bearings. The data input on a chip is super high impedance though. It may be 10KOhms or more. So the data outline is beating on the door like crazy but the door is made of concrete and isn't going anywhere.
Where does the voltage go? If current is high, as is the theory, then this chip is dropping voltages. Its dropping the same it normally does PLUS whatever extra voltages there is. Since the chip can only produce heat as a byproduct of switching this means that all the voltage drop is basically coming from arcing at the data lines.
Right? I think so. What makes connections arc is a difference in voltage between the two points. Connecting 5V to 5V does nothing. Connecting 5V to 0V will make shitloads of heat and melt everything if a breaker doesn't stop it. The increase in heat dissipation at the data line could be felt on both sides of the bus. In addition to arcing you have the possibility that the chip's lack of fortitude is causing data lines to flow more current, probably way more than normal since normal is almost immeasurably small. This could be within the ability of the game machine or maybe not. We know it wouldn't be anything the designers planed for since they were using 5V ROMs. These ROMs don't let the knocking on the door push the whole building down like the 3.3V ones do when you overpower them.
So is there a way to do this? Oh sure. Moving from one voltage range to another is just part of electronics design. It's not as simple as adjusting a level though. You need to give the bus a 5V door to knock on, and then pass that on as a 3.3V knock without any latency or hysteresis of any kind. It has to put out a perfect square wave just like the source but at a lower high voltage state.
The data line back from the cart to the bus will now need its 3.3V boosted to 5V. Again, it must be perfect and the extra voltage can't come from the 3.3V flash.
So presumably level modifiers are chips that do this. They can handle data coming in at one level of voltage and then pass it along at another without f*cking up the data and while isolating each complaint so that everything works within its spec and can't have a low resistance component somewhere down the line causing high current draw.
Ok. So how many lines is that on a game cartridge? I think the guy say twenty some for a Genesis. Now look at that Neo cart.
Holy shit. Their PCBs will have to become much more complicated to accommodate this. Also, it's good to hear that the NeoSD thing is fully legit in this area. That certainly helps sell the case to me that that is a well make product.
As for a game Genie kinda thing...maybe, it depends on the system, but it would cost more than the POS flash cart you're trying to fix with it so you should just buy the next version of their POS, I guess.
I will fix those typos later...
