Here's how the underside of my GameCube looks. ...I swear I still have the hi-speed port cover, I just normally leave it off.
Normally the hi speed cover is off and the port accessible as I leave the Game Boy Player connected. For many people the GBP's a useless lump of plastic... I still have the startup disc. (Nice!) As a self-professed lover of the GBP, a lot of my time with the Cube is spent playing GBA carts.
So of course I knew that hi speed is for Game Boy Player. What's so hi(gh) speed about the GBP? Who knows. (Well, now that I know the GBP has a GBA's guts that it uses to run the game and the GameCube acts essentially as a fucking video adapter for it, it's probably high speed because it's transmitting some form of uncompressed video...)
But I always wondered what the hell those serial ports were for. I knew serial ports from PCs, but they certainly look nothing like those d-sub connectors.
I know now that the first serial port took a modem and LAN adapter Nintendo made for playing a singular video game online. I didn't have an internet connection, so that was off my radar.
But the fuck does serial port 2 do? It has so little use that Nintendo removed it from later models of the console, along with the digital output. Is it like the GameCube's naval?
The answer... may shock you. Because the answer is that it's for... reading SD cards.
What.
This is what is known as the SD Gecko. It's an adapter that lets you plug an SD card into one of your GameCube's memory card slots. Wild! I always thought it was created for homebrew, but it turns out... it's of Nintendo's making. Apparently in Japan it was possible to save your Animal Crossing town to an SD card.
So how the hell does this crazy adapter work? Well it's... passive. Turns out the GameCube memory card interface is similar enough to the SD card interface that you can just... connect the card directly to it, and software that knows how to can read and write an SD card through the memory card slot. Nintendo makes weird stuff.
One interesting property of this is that since the interface is controlled by software, it can support SDHC cards which didn't even for most of the GameCube's lifespan.
I'm guessing the Wii's actual SD slot works similarly, seeing as a firmware update added SDHC support.
But what the hell does serial port 2 have to do with this? ...well, it turns out SP2 is almost the same as the memory card interface too. If you could connect an SD card to it... software that knows how can interface with the SD card... through the weird bottom port.
So some smart person created the confusingly-named SD2SP2.
I'm sure Nintendo did not put this port on with the intent that people could make little circuit boards with SD interfaces on them in order so people could load homebrew and pirated games from an SD card... more likely, they had something with memory cards or data transfer in mind that never made it to production.
But because of it, you can just shove an SD card in there. Neat.
@onfy it's just SPI isn't it? doubt they even made it specifically with SD cards in mind then
@noiob Yeah I think that's the term. Couldn't quite remember it, thanks.
@onfy yeah, most microcontrollers support it. SD cards usually aren't used via SPI these days because it's slow, but it's probably still fast enough for the Gamecube https://en.m.wikipedia.org/wiki/Serial_Peripheral_Interface
@onfy kinda funny that all their consoles past the GCN came with an SD card reader built in
@noiob What's so funny about that?
@onfy oh right, I never bought anything on there
@noiob As a kid the Wii shop was a godsend. Steam cards weren't a thing yet, and of course I didn't have a credit card. Was my only place to get a lot of games.
@noiob There were also a few good exclusives.
@noiob On the Wii at least it's useful for storing WiiWare, since the Wii only has 512MB of internal storage. Or it was when the shop channel existed...