pseudo code

If (power == off)

Hit either button to turn on

Else LCD displays “channel surf”

Button 2: cycle (channel input, volume, power)

Channel Surf

Button 1:  “enter” go into channel

Button 1: channel up

Button 2: switch to “channel down”

Button 1: becomes channel down

Button 2: exit

Channel input

Button 1: cycle digit (starting from hundreds, then tens, then single)

Button 2: enter

Favorite channel

Volume

Button 1: volume up

Button 2: switch to “volume down”

Button 1: becomes volume down

Button 2: exit

Power

Button 1: power off

Button 2: exit