1. Make a copy of program 2.1 and modify it so that the light goes off when the button is not pressed. Your new program should be exactly the same size as the original.
   [Exercise 2.6 (ex26.c)]

2. Make a copy of program 2.2 and fix it so that if both buttons are held down the light goes out rather than flickers. I suggest that you look at performing a third test which uses a logical && operation to see if both buttons are down and then turns the light off if they are. Remember that if you do this you don't want to look to see if either of the buttons are down as well, otherwise they will still flash! You can ensure that statements are not performed by using the else addition to an if construction or you may find a use for the continue.
   [Exercise 2.7 (ex27.c)]

3. Make a copy of program 2.5 and change it so that the light does not go off if the button is held down. You should be able to get this effect by making the program smaller! (you might find it useful to make the time out period smaller when you are testing the program)
   [Exercise 2.8 (ex28.c)]

4. Create a new program which implements a "coin tosser". The program will flash a LED very quickly while a button is held down. When the button is released the flashing will stop and the led will be lit or not lit with a 50/50 probability. Do you think you need to worry about debouncing the signal in this case?
   [Exercise 2.9 (ex29.c)]