It's simple. The idea is to have the guts of an Everdrive 64 inside the console itself that can be run, AND still allow the N64 to play games from the cartridge slot as it normally would. But how would we do that? Hooking up two N64 cartridges to the system at once won't work, for obvious reasons. So we have to have some way to switch between the cartridge slot on the console and the ED64 inside it, digitally. The simplest way to do this would be to just switch the power supply between each cartridge. No power, and the cartridge won't work, right? Unfortunately, it doesn't work out this way. Leaving all the other pins hooked up allows for backfeeding. We'll have to switch all of them as well. Enter the mutliplexer. We take all 28 lines required for a cartridge to run form both the ED64 and the cartridge connector It works by hooking up the ED64 and the cartridge slot to a multiplexer bank. This bank acts as an electronic switch, allowing either the pins from the ED64 or the pins from the cartridge slot to be hooked into the console's motherboard. Just hook up the wires, supply the correct signals, and make a circuit to switch the muxes to the ED64 when a cartridge isn't inserted. I've got a few questions about how to make this setup work, though. I'd like to hear from you if you know anything asked below. What's the easiest way to detect a cartridge inserted in the cartridge slot? I could rig up a simple switch, but is there anything already on the N64 to tap into? The largest DIP 2:1 multiplexer out there only has 4 poles (at least from what I can find on digikey, mouser, ebay...), meaning that you would need a bank of 7 of the suckers to switch all the pins on a cartridge. Does anyone know of any through-hole 2:1 multiplexers with more poles? Is there any simpler way, perhaps using tri-state drivers? (If you haven't yet noticed, I'm not terribly experienced with electronics) Do ALL the pins need to be switched to prevent any complications from two cartridges? Has anything like this been done before? Any thoughts on this at all? J
Funny. I was gonna start a thread about having two cartridge ports on a system too, but you beat me to it. In my case I want to consolize a Game Gear, and have both a Game Gear slot and a Master System slot on it at the same time. I'm also looking for a way to have the system favor the Master System cartridge over the Game Gear one. So if I had one of each inserted the system would just ignore the GG cartridge and play the SMS one instead. I would prefer if the system could detect this automatically so I wouldn't need to flip a switch to switch between inputs. So basically I'm looking for exactly the same answer as you are
Seeing how the N64 doesn't switch to another mode of operation when there's no cart, I don't see why there would be. Maybe you could tap into the slot's power supply lines and see if there's a current? Anything power related should be fine to stay connected. But that might make the everdrive produce heat even if not in use. My hardware-fu isn't too strong, but you might even be able to get away with leaving the address lines and only disconnecting /read, /write, audio and clock signals (since the cart won't do anything without a clock, and even if it does it's not allowed to get/put any data to the N64's bus... Uh, right?) Had a very similar idea this morning in the shower, only mine was a "cart-less" SNES. Personally I don't really see the need for a(n externally accessible) working slot when I can run every. single. game. directly from the Everdrive (that's even more true for the N64 than for the SNES with all its special chips...). Also, space might be an issue.
Does the ED64+ made by Super Ufo allow you to play the cart plugged on top? I know the SNES cart by Super Ufo allows that.
I have a DRv64 Jr 512mb and I can use just the cart slot on it via software.. Not quite the same but may help
I remember bacteria making a goldeneye only N64 as a commission. Guess you could do something similar but of course modify it. How the V64 works, is that the data is passed through the rear port, and games are passed through the top port, there's an adapter which blocks some pins out but I'm sure there's something you can do about this. Not that I'm technically just throwing that out there
First of all don't use that rip off cart. It doesn't support the original developer and it's very poorly assembled. I wouldn't permanently install one of these inside the console as it would probably fail rather quickly. Second, it wouldn't work. Only the CIC lines are passed through. No other signals are taken from the top cart. For the cart switching, quickly looking at that site : http://www.crazynation.org/N64/n64_cart_info.htm I'd formulate an hypothesis that you could wire in parallel all the pins of both carts except for 4 signals: /read, /write, ALE_L and ALEL_H. To disable a cart, keep both /read and /write high and ALE_L and ALEL_H low at all time. That should prevent any read/write operation from that cart. The only possible issue with that solution is that maybe the content of what's at address 0x0 could be sent to the console if /read held high doesn't put the data lines at High-Z. Also, both carts are powered at all time. If it was to work, I would prefer this solution to cutting power to voltage lines. There is a possibility that the ROM chip on the disabled cart gets powered by the address lines and that could damage the N64 itself. These signals lines are not designed to drive or sink power. For this you'd only need a fast CPLD (100MHz or more) and maybe an oscillator if there is no place to get a clock from the console itself.
Yeah, I might have been a bit inaccurate in my phrasing there. What I meant was: On the SNES a working slot might make sense due to various titles with dedicated hardware. On the N64 there's absolutely no reason to keep it.
