NAND Logic Gate

Thread Starter

mechatronics_student

Joined Sep 26, 2012
2
Hey there!!

Right now I am stuck with my logic gates homework... The only one that I need to finish it is one application for NAND logic gate... Guys I really appreciate if you can give me Ideas... thank u!!
 

Austin Clark

Joined Dec 28, 2011
412
Hey there!!

Right now I am stuck with my logic gates homework... The only one that I need to finish it is one application for NAND logic gate... Guys I really appreciate if you can give me Ideas... thank u!!
Maybe a seat-belt protection thing? If there's weight on the seat (Which we'll represent as a 1), and the belt isn't buckled (Also represented as a 1), the car won't start (0).

EDIT: Actually, that's a pretty poor example... I'll come up with one better later :)
 

MrChips

Joined Oct 2, 2009
22,107
Start off by understanding what a NAND gate is.
It is an AND gate with a negated output.

Find two conditions that must occur together before something is allowed to happen.
Now negate the outcome.

Find two conditions that must occur together before something is disallowed.
 

Thread Starter

mechatronics_student

Joined Sep 26, 2012
2
Maybe a seat-belt protection thing? If there's weight on the seat (Which we'll represent as a 1), and the belt isn't buckled (Also represented as a 1), the car won't start (0).

EDIT: Actually, that's a pretty poor example... I'll come up with one better later :)
Actully I understand what is a NAND gate...

But... I need an example in real life...
 

WBahn

Joined Mar 31, 2012
26,305
Actully I understand what is a NAND gate...

But... I need an example in real life...
So find something where knowing that both conditions are True tells you that some other condition is False (and, otherwise, it is True).

Putting it in English terms, you might say something like, "This will be false if both this condition is true AND this condition is true."

Conversely, another way of saying this is to find something (the output) that is dependent on two things such that the something is True as long as one of the things it is dependent on is False.

Putting this in English terms, you might say something like, "This will be true UNLESS this condition is false OR this condition is false."

Yet another way to capture this notion in English terms would be, "This will be false if EITHER this condition is false OR this condition is false."
 

MrChips

Joined Oct 2, 2009
22,107
An AND condition occurs in many security checks.

Your USER NAME is valid AND the PASSWORD is correct -> ENTRY is allowed.
Now you need to turn that into a negative outcome.

Your USER NAME is valid AND the PASSWORD is correct -> You are NOT prohibited.

You can use DeMorgan's theorem and turn that around to an OR gate.

USER NAME is NOT valid OR the PASSWORD is NOT correct -> You are prohibited.
 
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