I just received, for Christmas, a new 512MB miniSD card for my cellphone, so that I can use it for listening to MP3s and the like.

All I have to say about it is that this tiny little thing RULES. It has a 512MB capacity, and it is VERY fast -- I'd say about 50 to 100 times faster than a floppy drive, as used in my cell phone. While it is not as fast as the harddrive on this PC, it's fast enough to transfer a 5MB file from the harddrive to the MMC card in about 1 second, via Windows XP on an HP 519J computer. And this is with the 9-pin MMC interface; the 13-pin interface would be expected to be faster still, if the MMC card (and reader interface) supported it.

As I recall, the MMC form factor and basic specifications appear to be freely available, as I remember doing some research on it in the past. The "free" specs didn't give you all the details of the interface, but presumably gives enough to read, write, and format the device. I can't recall URLs now because I'm at my family's computer, and don't want to disrupt their PC's URL history too much.

At any rate, I do know for a fact that MMC cards can be used in SPI mode, where you'll take a small hit in performance in exchange for ease of interface. I also recall seeing that DigiKey has an MMC socket for about $5.

If anyone is looking for a serious solution to removable media with the convenience of a floppy disk but with the capacity of a small harddrive, MMC is *the* way to go. I *strongly* recommend it!

I use them in SPI mode controlled by an SX microcontroller. I agree, they totally rock. And they come in flavors up to 2GB (thus far).

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Thanks for playing.
-- Lord Steve