I have an Arduino Uno R3 board and successfully used it to program my first ATtiny85. I followed the MIT Media Lab instructions and, in burning the Bootloader, selected "ATtiny85 (with internal 8MHz clock)" in Tools>Board.
Moving on to my second ATtiny85 I got careless and, in burning the Bootloader, I accidentally selected "ATtiny85 (with external 20MHz clock)" - the next one down in the Tools>Board list. When I subsequently tried to re-burn the Bootloader having now selected "ATtiny85 (with internal 8MHz clock)" I get the following error message:
"Yikes! Invalid device signature. Double check connections and try again, or use -F to override this check."
Is there an easy way to put this right? I am very much of a beginner.
What does "use -F" mean and would that solve the problem?