For everyone out there who currently owns a Windows Phone 7 handset, do yourself a favor and do not tinker with adding, removing, or upgrading the SD capabilities of your phone. Microsoft does not want you to, your phone will not like it, and it could cause you serious problems.
At least that is, for now. Microsoft actually put together an extensive technical document on the subject of microSD cards and WP7 devices that we will paraphrase into a few things shortly. If you want to read the whole page, head over here.
For starters, removing an installed card could result in “all phone functionality [being] disabled except for the ability to make emergency calls.” If you add an microSD card, you can expect performance issues not limited to “applications might start more slowly or not at all.” Or with even more brevity: touching microSD card bad.
Why all the kerfuffle over a darn card? As it turns out those are no regular microSD cards, they are ‘Windows Phone 7 Compliant SD Cards,’ in case you were wondering. Yes, they are special, and that is exactly why you do not get to swap them around.
Engadget summarized the situation succinctly:
The official guidance at this point is that we need to wait for cards that are specifically certified for Windows Phone 7 [TNW: to swap them]… and since those cards don’t exist yet, we need to hang tight. But what constitutes a certified card, and why can’t we get them yet?
Fair questions, and we don’t have the answers. Microsoft has this to say about the cards that are oh-so-special in their eyes: “Windows Phone uses a special high–performance SD card that works differently than SD cards in other devices. When your phone is built and first set up, its internal storage and SD card are combined and recognized as one storage system.”
That makes some sense, Microsoft is in short using the cards as a non-removable form of storage that can be bridged to boost the handset’s traditional internal storage. Once the card is installed, it’s almost tied into the system that it has been formatted into, making it hard to swap.
What exactly “special high–performance” means remains to be seen, but for now just don’t touch your WP7’s microSD area, you won’t win. When we know how to hack the buggers, and where to buy these special cards, we’ll let you know.