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Mental Vortex

NES expansion slot - was it used for anything?

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My friend Chris got a NES around 1986 or so. He heard a rumor that you could play Sega Master System games if you plugged them into the expansion slot at the bottom of the unit. Needless to say, it didn't work, and he gave me his copy of Space Harrier that he bought just for that. I still need to get an SMS one of these days, but that's for another thread.

Anyway, was the expansion slot ever actually used for anything? I did a quick search on this site and couldn't find much that talked about it. I always wondered if was just there and never used or what.

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I think in japan the bottom port was used to connect the famicom to a device that would let you play disks that you could buy at dispenser kiosks elsewhere. I am sure someone else will be able to explain better.

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[quote name='Dones']I think in japan the bottom port was used to connect the famicom to a device that would let you play disks that you could buy at dispenser kiosks elsewhere. I am sure someone else will be able to explain better.[/quote]NEgative.
The FamiCom Disk System connected through the CARTRIDGE slot.

The FamiCom expansion port was a DB15 on the front of the system. And was used heavily, because it was the only way to plug peripherals in.
Remember, the FC had hard-wired gamepads. The FC expansion connector is an overglorified controller port.

The US one is, if I recall, an overglorified controller port with a partial cartridge bus added on.

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You see? I knew JB couldn't resist the chance of taking a completely good natured post and turn it into an excuse to try himself to know more. Come one JB, throw a snappy remark and get over with it. :roll:

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[quote name='Dones']You see? I knew JB couldn't resist the chance of taking a completely good natured post and turn it into an excuse to try himself to know more. Come one JB, throw a snappy remark and get over with it. :roll:[/quote]
*scratches head*
Have I actually done anything to offend anyone on this board?
I've got no clue what the hell your problem with me is.

I was just offering some relevant information, and correcting a quite understandable misconception at the same time.

I'm sorry if you find the sharing of knowledge offensive. I thought that was what this board was for. My mistake.
If the edit button was available, I'd change my post to "yup, and the FDS plugs right into a US expansion port too" just to appease you. But it isn't, so I guess actual facts will have to stick around offending you.

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Mental Vortex,

Expansion slot at the bottom of the NES was never used for anything. there was idea's but never anything real like a disk drive or maybe like the Japan SNES famicom SATELLITE add-on thing. One Thing that got into proto stage was a stupid gambling devices system that connected to the phone line I think or what ever crap.

I don't even think classic gamers made it work for any home brew devices so it never was used so fare... (As with the one on the US SNES I guess ? )

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[url="http://www.atariage.com/forums/viewtopic.php?t=44263"]http://www.atariage.com/forums/viewtopic.php?t=44263[/url]

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I want to use mine. I need someone to build me an adapter so I can use the Famicom Basic Keyboard and the 3D Goggles with it. I *think* it's possible to do that, but Im not sure it as all the lines that the Japanese one had.

Tempest

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[quote name='masschamber']The miracle piano uses it  and some sort of minesota modem[/quote]

The Lottery modem?

[url="http://www.megspace.com/entertainment/neskingdom/special/lottery/index.html"]http://www.megspace.com/entertainment/nesk...tery/index.html[/url]

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The NES Expansion port contains all the functions of the Famicom Expansion port and a whole lot more. Just because it wasn't used, except for the Minnesota State Lottery device (and that was just a prototype), it doesn't mean that it cannot be used in a homebrew device.

The Miracle Piano plugged into a controller port, not an expansion port.

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I found this:

[url="http://www.everything2.com/index.pl?node=Nintendo%20Entertainment%20System"]http://www.everything2.com/index.pl?node=N...inment%20System[/url]

[quote]Famous Vaporware: The Telegames modem would have snapped on to the bottom of the NES and accessed its expansion port to allow online play. Note that by "online" I mean that the NES would physically call the person you wanted to play against and make a direct connection to their NES. No Internet, no central game server. The device never made it to market.  
[/quote]

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So someone built a way to interface with it, but...doesn't seem like there's much point.

 

Wasn't there some way to get additional sounds from Famicom games like Castlevania 3? I seem to remember reading that here once upon a time.

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So someone built a way to interface with it, but...doesn't seem like there's much point.

 

Wasn't there some way to get additional sounds from Famicom games like Castlevania 3? I seem to remember reading that here once upon a time.

 

Yup :) Shorting pin 3 and pin 9 together allows Famicom games played on the NES to use "Expansion Audio". Only problem, is the fact that grabbing Expansion Audio from pin 3 of the expansion port tends to make the expanded channels greatly overpower regular audio. People suggest putting a 47K resistor there, but I've personally found that 10K works much better overall.

 

If you really want to fine tune the audio, you could simply wire a 50K pot to pin 3 and 9 and adjust on a 'per-game' basis. But that's pretty much overkill. I recommend 10K's of resistance between the two pins.

Edited by SwampFox56

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The expansion connector is used in a homebrew sort of way. Audio can be supplied from the cart bus to the internal sound mixer using a 47k resistor. I used a grounded 10k audio pot instead to tweak the gain on the expansion audio from 0-100%. It sounds balanced at about 2/3 max setting. Other homebrew uses of the unused cart bus is to reprogram carts utilizing flash mappers. Also as previously mentioned, you can wire up a Famicom EXT port on your NES using a DB 15 male connector. It makes it slightly easier to use the expansion pins if you desolder the entire Expansion connector and solder directly into the through hole vias.

 

@SwampFox56: A 50k or even 100k pot in series with the audio path would only reduce the level somewhat. You would notice very little change until the resistance becomes low, then loudness rapidly increases. A proper volume control uses a voltage divider which connects the source to ground via a series resistance. The sweeper arm connects to the output allowing the signal to vary from ground (0v) to 100% of the source signal.

 

The mixing circuit inside the NES already has a 22k resistor connected to the AUDIN pin. The CPU have an additional 22k and a 12k resistor on it's two pins. The mixer takes the combined signal from these three sources. Powerpak and Everdrive output a louder signal than the NES CPU, so it somewhat overpowers the NES CPU. To compensate, a 47k resistor is added in series, making the total resistance from Powerpak to the mixer equal to 69k. Using a 50k or 100k pot only varies the series resistance from 22k and higher.

 

My audio pot mod connects an audio taper 10k pot to ground on the low side. The high side goes to the NES Powerpak pin on the cart bus and the middle pin goes to the mixer by way of AUDIN pin on the expansion bus. To minimize the noise, all three wires are kept closely together from the pot to the expansion bus. I have pins 2, 3, and 9 connected to the pot. I also added two 47uF electrolytic caps in series to the circuit to remove any DC bias (high pass filter well below 10Hz) isolating the PowerPak and AUDIN pins from DC ground, but this step is probably unnecessary. The mixer can handle grounded input because of the 22k resistor already present on the motherboard, and grounding the AUDIN pin generates a lower noise floor compared to leaving the long trace all the way to the cart bus floating (which is essentially what Bunnyboy's 47k resistor does), as any long trace connected to an amplyfying circuit makes an excellent antenna for noise.

 

With a 10k volume taper pot acting as voltage divider by supplying the expansion audio signal to the mixer, I get "balanced" sound with the knob about 2/3 of maximum volume. I have three carts that use expansion audio, Powerpak, Everdrive N8 (Famicom version), and a Mr Gimmick repro. Everdrive N8 does not work with CopyNES, nor do I have an expansion audio jumper in my Famicom-to-NES adapter, so I'm unable to test it on anything but my AV Famicom. Tweaking the audio is nice and it's fun to experiment because you can hear the difference between the NES audio processor and the expansion sound.

 

I have a nice big red knob on my NES for tweaking the expansion sound, curtesy of Radio Shack... 8)

 

post-33189-0-05077700-1407810023.jpg

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