Hello,
I just got my first arduino. Its an original 101. However, I am unable to run a single sketch since the serial port doesn't show my arduino. I have tried reinstalling different IDEs twice going back to 1.6.9. Also, I upgraded to El Capitan from Mountain Lion. I am attaching a screenshot. I am clueless since I am a beginner and also I found no resources specifically for this problem related to El capitan and Arduino 101
update 1
My board does turn ON. And the MAC does recognise the Genuino 101 as I checked on the Hardware>USB under About this MAC
update 2
I don't really have an idea what happened. I will mention few things here. I uninstalled my Arduino from the mac. I think I had left one library folder on my mac. SO the IDE wasn't uninstalled fully. I did it this time. I reinstalled a 1.6.10 IDE.Strangely when I started it, it asked me for an update to some WIFi adapter. And it showed only two native ports-the incoming bluetooth and one for my BT headset. As soon as I plugged my board in, and refreshed the list for ports, a third serial port popped up dev//cu.usb. something like that. I chose that port and uploaded my first sketch, the Blink example and Voila! it ran :). I think the issue is now solved.