Author Topic: The Universal Logic Gate  (Read 10022 times)

Offline frenulem - No.5417

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The Universal Logic Gate
« on: November 27, 2010, 02:20:12 PM »
Logic Gates, Please read before continuing!

NANDLogic gates are known widely known as the universal building block or universal logic gate, this is because you can build every type of logic gate with just this one gate wired in different ways.

The advantages of using the NAND gate is that logic gates come in chips, generally 4 gates to a chip and all containing the same gate. so using NAND gives you these advantages:
            1. Less cost
            2. Smaller PCB
            3. No need to keep as many chips
            4. Less soldering

The disadvantage of not using NAND is that you have to many free spaces for example 4 chips each having 4 gates to only use one of each gate in a chip, so using 4 Gates out of a possible 16 this means:
            1.Costs are grater than need be
            2.Your PCB Layout will be more complicated and large
            3.Spend more time than needed designing your PCB



Not to much info on the gates themselves because that's all explained in the link at the top of the post.

NAND Truth table and symbol


 The NAND truth table
A   B | Q
0   0 | 1
0   1 | 1
1   0 | 1
1   1 | 0


The six possible gates to make are:

            1. NOT
            2. AND
            3. OR
            4. NOR
            5. XOR or EXCLUSIVE OR
            6. XNOR or EXCLUSIVE NOR

NOT


Truth table
A | Q
0 | 1
1 | 0

Simple NOT gate, inverts the input, made by joining the inputs together



AND

Truth Table
A   B   C | Q
0   0   1 | 0
0   1   1 | 0
1   0   1 | 0
1   1   0 | 1

A NAND and an NOT linked together, easy.



OR


Truth tables
A   B  C    D | Q
0   0   1    1 | 0
0   1   1    0 | 1
1   0   0    1 | 1
1   1   0    0 | 1
A NAND and a NOT gate joined together like ebony and ivory.



NOR


Truth table
A   B   C  D   E | Q
0   0   1   1   0 | 1
0   1   1   0   1 | 0
1   0   0   1   1 | 0
1   1   0   0   1 | 0




XOR or EXCLUSIVE OR


Truth table
A   B   C  D   E | Q
0   0   1   1   1 | 0
0   1   1   0   0 | 1
1   0   0   1   1 | 1
1   1   0   0   1 | 0



XNOR or EXCLUSIVE NOR

Truth table
A   B   C  D   E  F | Q
0   0   1   1   1  0 | 1
0   1   1   1   1  0 | 0
1   0   1   1   1  0 | 0
1   1   0   0   0  1 | 1


Images to come as soon as I can get mahself a Nand chip :)
« Last Edit: February 14, 2011, 05:47:18 PM by FOOKz »

Offline HiddenVenom

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Re: NAND Logic
« Reply #1 on: December 06, 2010, 04:33:52 AM »
Yeah, the XNOR works.

 

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