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What Are The Expansion Ports Under A NES And N64 Used For?

Nintendo 64DD Disc Drive

These days, game systems come with all kinds of I/O ports—USB, HDMI, Ethernet, Optical Audio and more. These portals are used to do everything from log online to connect digital cameras.


But believe it or not, back in console gaming’s retro heyday of the ‘80s and ‘90s, you’d be lucky to get one port on your console—the stock “expansion port.” Typically these were used to connect hardware and expand gameplay. But, interestingly, not all ports were that functional.

Case in point: look under your old NES or N64 system and you’ll find a 48-pin port hidden behind a snap-in case. Kids who discovered this in the ‘80s were understandably excited. Maybe it was for some cool peripheral, like a new light gun or a different controller. But no one ever found out what, exactly, the port was for.

So, in the interests of putting rumors to rest once and for all, here’s a definitive look at what those ports under your NES and N64 actually do.

nintendo bottom expansion port Nintendo NES Expansion port

There are many rumors surrounding the NES expansion port: what does it do?; is it a cartridge slot?; does it connect games from other systems? As for the last theory, one rumor held that the port was compatible with Sega Master System games. But unfortunately that’s been debunked. Try attempting the connection yourself with an old MS game and you’ll be disappointed.

The awful truth is that nothing was ever developed for the expansion port, so in point of fact it actually does nothing. There were other rumors that back in Japan the port was used to connect the Famicom console, but this seems to be a red herring as well (and if your broach the issue on message boards, you’ll likely get a random smackdown from certain ill-tempered Nintendo enthusiasts. There was also hearsay that Nintendo was going to use it as a connector for a modem developed by Teleplay, but that’s a dead end as well. The modem never got beyond the prototype stage.

Ironically, though, the folks at Hackaday reported on a hobbyist who got some internet mileage out of the expansion port. In 2015 he modified the port to send tweets from his NES. It seemed to be a time-consuming project that cost at least some amount of money. So we recommend that if you really need to tweet you should just do it the old fashioned way and pick up your phone.

 The N64 expansion port

N64 gamers are aware that the console did indeed come equipped with a useful memory expansion port on the top of the machine. It’s here you stuck in the Nintendo 64 Expansion Port | N64 bottom Expansion Port pak. So Nintendo must have evolved and added a bottom expansion port that actually did something, right?

Sort of, but not really.

The bottom port was compatible with the N64DD (Disc Drive), which was only ever released in Japan. So while gamers in the far east could connect their machines to a portable disc drive, the project was cancelled before it saw worldwide release. So, again, the N64 expansion port basically did nothing—no peripherals, no modem, no controllers.

But, hey, you could still do that twitter modification if that’s what floats your boat.


Ultimately it wasn’t until the 2001 release of the Gamecube that Nintendo had a machine with real expansion possibilities. There were three ports—two serials and a hi-speed. And even though all these ports saw worldwide release, Nintendo just couldn’t help themselves: one of the serial ports (the smaller one) remained unused.

Did you know that we buy used video games and sell N64 games directly on our website?  We have great prices and lots of retro video games to choose from.  Come On, Let Go Shopping!

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Comments 1

Guest - Saphie on Monday, 25 January 2021 16:16

the original snes has one under it too. but was used for the excise bike.

the original snes has one under it too. but was used for the excise bike.
Thursday, 28 October 2021
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