How to make a multi-cartridge selector like Neo-Geo?

[Turnarcades]

OK. I'm planning on building a series of arcade machines, each running a different console inside. Been to the drawing board a few times so I've got designs in mind, most of the connectivity and even the region lock-out issue by selecting hardware that will run multiple regions. My main design involves mounting the cartridge slot on the control panel so the game can be changed easily, but for convenience I'm now thinking how great it would be to create a multi-cart system where a bank of say 5 connectors can all be mounted, then the game selected before powering up the system by a switch or something.

I've read around a bit and know that there were multi-cart systems made for kiosk use for many systems including NES, Megadrive and some others so I know it's possible but tracking down and buying one of these isn't an option. I know there were also multi game arcade systems like Megatech, NSS and Playchoice but again the idea is to create a machine that uses proper home cartridges. There are now multi system clone consoles that effectively do this (switching between not just games but whole platforms) and there are multi- JAMMA connectors that work like this, so there must be a simple way!

I've had a quick check over the internets in the usual places like benheck etc but no concrete answers. Can anyone here help?

[Howard_Casto]

Disclaimer:  I'm not an electronics expert!  These are just general ideas that may or may not work in practice.  

There are of course issues with shorts and back-flow, but typically every cart has a chip(s) in it and these chips are completely inert, regardless of what data you send to them unless they are powered up.  So the easiest way to build a switcher is to wire every single slot into the console like a giant "y" cable with the exception of the power (and possibly the ground) pins.  Those pins get switched by either a chip or a physical switching system.  It's also important to note that the button for selecting a cart also needs to be wired to the reset switch so that the game momentarily resets when you change games.

Of course some consoles and some carts might get damaged with such a setup, we are just talking in general here.

Your problem of course is going to be finding the cart connectors.  About the only way you can get them (with a few exceptions like the nes) is to take them out of an old console.  Even then it'll be expensive.  Please don't kill 30+ consoles just to make your multi-adaptor.  



Also, just for the record, multi cart systems on arcade machines are NOT the model you want to go after.  At lot of them simply power up all the boards at once, leaving them running all the time.  The selector switch simply changes the video and inputs, like a KVM switch for a computer.  To use that model you would need multiple console units.

[MonMotha]

Actually, many IC designs are NOT passive when unpowered.  They'll hold the bus in a "low" (grounded) state.  Even if you remove both power and the ground reference, you may have problems with it trying to hold all the bus lines at the same state.

Also, even at the relatively slow bus speeds used by old console gaming systems, attempting to run several carts to the console without any buffering, especially over long-ish wires, is quite likely to result in signal integrity issues.

What you'd probably have to do in this case in order to make it reliable is buffer each cart individually logically ANDing the buffer enables with "cart slot enable".  This isn't *too* hard.  IIRC, it's roughly what's done on the multi-slot Neo-Geos.  It does require knowing a little bit about the cart interface on your target systems, but most of them are so old at this point that somebody's probably worked it out.  You'd probably want to make a PCB to do it, just because the number of connections is high.  That would also give you a structure to mount the card slots themselves on, which could be handy.

If you're really interested in it, this is something I could design for you.  Send me a PM if so.  It may be cheaper to just chuck multiple consoles in the system and switch the video/controls, though.

[Mac Green]

multi try this out http://www.ebay.com/sch/i.html?_from=R40&_trksid=p5197.m570.l1313&_nkw=retron+3&_sacat=See-All-Categories     and here