The sketch and cable ( as shown here: http://www.gammon.com.au/forum/?id=11635 ) work perfectly with all other arduinos (duemilanove,UNO R3 and BBB) I have tried, but it does not react to my Mega 2560 R2 and R3 boards.

I am concerned about the Mega R2 as it does not communicate at all with the IDE (the main reason I found your page in the first place), but the Mega R3 is in perfect order and yet behaves exactly the same way - it just displays the two top lines:

Atmega chip programmer.
Written by Nick Gammon.

Any suggestions for this odd behavior? I am using Arduino 1.0 and tested both in XP and Windows 7 with same results.