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Homework Statement
Digital Combination Lock: To create a circuit that verifies the input from a hexadecimal as 5-A-7 and then lights up an 'Unlocked' LED. (DONE)
Bonus Points for:
The obvious limitation of this circuit is that the combination cannot be changed. This limitation can be
corrected by adding sufficient memory to store three hex numbers and a means of switching between
"program mode" and "operation mode." If you wish, you may use separate keypads for each hex digit and
the "input" (giving a total of 4 keypads). If you prefer, you may employ one keypad for programming and
another for input with a means of switching between each of the three digit storage cells. You may, if you
wish, use only one keypad for operation and programming all inputs. The choice is yours.
For full extra credit:
• Any hex digit 0 . . F can be stored in any of the three memory cells.
• The hex digits stored in the memory cells, result in a new combination for the lock and the lock will
open when the new combination is supplied via the input keypad.
• The combination is stored (persists) until it is changed by reprogramming the lock.
• The circuit uses only standard combinational and sequential logic components
Homework Equations
I am unable to understand what exactly can I use to 'store' the correct input value?
The Attempt at a Solution
attached is the basic circuit I created that verifies 5-A-7.