I think it is a bit off topic, but I found no better post for this topic.
I wanted to use the famous TinyISP programm to allow serial debug output
of an ATtinyx5 into the Arduino IDE Serial Monitor
Unfortunately the ATtinyx5 pin number in file TinyDebugSerial.h was not set to fit the standard ArduinoISP setup.
I had to change the pin number from 3 to 1, then it worked (CPU clock 1 MHz).
I have documented all that on my web page: http://www.rudiswiki.de/wiki9/AVRTinyISP
Regards to Coding Badly for the good software.