Jim, Tones(*) is an array for storing the incomming touch tones. The first 4 tones are the password. The tone is decoded into a nibble of either 0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f. These are shifted into a word sized variable called codewrd. After all 4 tones are shifted into codewrd it is compared to a constant called unlock. It once again can have a value of 0000 to ffff. If the two compare then the system is unlocked...... This same type of method can be used for even longer unlock codes.

Dave Purola,