Saturday Mac riddles 12

Here are this weekend’s riddles to entertain you through family time, shopping and recreation.

1: I’m silica on silicon, and at heart of your images. What am I?

2: I sound like a physicist’s handwriting, but my origins were reflexive and had roots near Boston. What am I?

3: Whose initials appear in more files than any other?

I will post the answers first thing on Monday morning.

Please don’t post your answers as comments here: it spoils it for others.