…from:
If your Mac or iThing runs Yosemite or iOS 8, it can run El Capitan and iOS 9
Apple doesn't drop hardware for the first time in a long time.
If your Mac can run Yosemite, it can run El Capitan.
Here's some good news for just about everyone: For the first time in many years, neither iOS nor OS X drops any current hardware from the system requirements list. If your device can run OS X Yosemite (or Mavericks, or Mountain Lion), it can run OS X El Capitan. If it can run iOS 8, it can run iOS 9. For your convenience, here's the complete list of Macs supported, pulled from this developer support page: