I would try something like this... I suppose? =)
In the main loop
If returnkey()=1
input "Enter Cheat: ";Cheat$
if Cheat$="Life" then Life=Life+1
if Cheat$="Armor" then Armor=Armor+1
endif
Where Life is your Life and typing Life in the cheat box gives you one extra life, same as armor. If you don't enter any of the cheats, it will not do anything, but if you want to have a "No such Code" message then do this.
If returnkey()=1
input "Enter Cheat: ";Cheat$
if Cheat$="Life" then Life=Life+1
if Cheat$="Armor" then Armor=Armor+1
else
Set Cursor 0,0
Print "No Such Code!"
endif
That does the exact same thing as before except it prints at 0,0 on the screen "No Such Code!" if you didn't type a right code!
Hope that Helps!