Q: My computer isn't acknowledging any SD cards I put in

Hello there, Profs.Plumb.

The following Knowledge Base article provides some great overall information in regards to SD cards and their functionality:

About the SD and SDXC card slot

http://support.apple.com/kb/HT3553#9

I put the card in the slot, but it did not mount.  What should I do?

Remove the card and insert it again. Sometimes, if you put the SD card into the slot too slowly, it may not mount properly.

There is also great information on the necessary formatting for cards to be recognized, in the article as well.

Thanks for reaching out to Apple Support Communities.

Cheers,

Pedro.