SD card size limitations

[yurihellsing]

Ok what part of a mobile device(s) such as phones and some MP3 players is it that limits the size of SD cards you can use?

 

Is it the OS?

 

Is it something on the board like some kind of controller chip?

 

or so they state "Up to XXGB" as XXGB was the biggest size SD card available at the time?

[Guest]

I'm thinking it's a combination of the OS and the chip. I had an issue with my 64GB microSD where it wouldn't work unless I reformatted it as FAT32 from exFAT.