Computers and music.

Did you know that in JS alert((![]+[])[+!![]]) does the same as alert("a")? This is why JSFsck works, actually.
Did you know that the magic number for JPEG is 0xFF 0xD8 0xFF?
Did you know that even though FT2 was abandoned by its original creators, it is still maintained by its users?
Did you know that there can only be 2 different hexatonic scales? Even though you can start either from any note, all the rest will be enharmonic with either of these 2.
Did you know that MS-DOS is still included in Windows for the sole purpose of making boot disks?
Did you know that the first programmer was a woman? I am talking about Ada Lovelace.
Did you know that the Internet was originally made in the 70s? It started as Arpanet, which, surprisingly, still exists.
Did you know that most violin concertos are made in D major? That is because D major is the easiest key for a violinist to play.

Fun fact #1: There are more computers than people in my house. Fun fact #2: I play the piano and am also a good singer. Oh, and also a decent composer. Fun fact #3: I can draw quite well, but am way too lazy to do so.