Cannot get Board Manager to show the microcontrollers attiny84 and 85

Development Tools IDE 1.x
4

Do this:

  • Tools > Board > Boards Manager
  • Wait for downloads to finish
  • Scroll the window down until you see the entry titled "ATTinyCore by Spence Konde". Click on it.
  • Click "Install".
  • Wait for installation to finish.
  • Click "Close".

You will now find new boards in the Tools > Board menu: "ATtiny24/44/84" and "ATtiny25/45/85".