.It gives more protection and used as door locking and safe locking method.
Your code can enter code from the left most logic switches.
There are 3 set having 4 switches . Each set for each number
Lowest one for one's digit.
Middle one for ten's digit.
Upper one for Hundted's digit .
Code series lowest logic switch in each set for MSB and upper one for LSB.
Initial code 851.
CODE ENTERING
----+++++------
Now unknown person will enter the code and if code is correct door opens otherwise remain close.
To enter the code .
Choose the digit in form of four bits by logic switches near 7 segment display.
After 4 logic switches there are 3 switches.
First for loading the digit serially .
Second to reset it.
Third as ENTER key.
After loading 851 to 7 segment diplay . Press enter key.
If code you enter is same as previously inputed code by 12 logic switches green LED blinks otherwise RED led remain blinking.
Hint : Green led for open door RED led for close door . Lowest logic switch for MSB and highest switch for LSB.
