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Renewable password

Posted: Tue Apr 04, 2017 2:40 am
by bruno212
We have a project that requires a user to enter a 4 Pin binary password for a safe box. Our professor requires the password to be changeable, however, in our lessons, we have only tackled about combinational circuits. How can we design a combinational circuit wherein the input-output scheme can be changed. thank you

Re: Renewable password

Posted: Tue Apr 04, 2017 3:21 am
by Hans Cadans
Hello Bruno212

I've read your question. Of course, it is not difficult, to give a complete solution.
I assume, you want to have a 4-bits solution.
I advise you, to design a 4-bits comparator. Such a design compares two 4-bits Numbers.
Every time, you change the nibble (4-bits binary number), to which your input is compared to,
you have to type a new password.

You can make this circuit with, only, primitives.
If you don't succeed, you can ask again, and I will help you further.

Best regards
Hans Cadans