Universality of nand and nor gates pdf files

The basic operations are described below with the aid of truth tables. Nov 10, 2015 and logic operation can be performed by using two nand gates, as shown in fig 5. Heres a questiondo you need all the basic gates to build all possible logic circuits. In this video, 2 applications of the nand gates are presented. Substituting nand gates for other gates all about circuits. From the truth table, we can say that the output of the or logic or an or gate is true or high or 1, even if either or both of a or b are 1. Nor gate is the combination of not gate at the output of or gate, hence nor gate is type of notor gate. An entire processor can be created using nand gates alone. In other words any logic circuit with or gates in first level and and gates in second level can be converted into a nor nor gate circuit. No 3 universality of nand nor gates nand gate nor gate. It shows the outputs generated from various combinations of. In digital electronics, logic gates are the certain type of physical devices basically used to express the boolean functions. If youre fresh out of nor gates, but have some nand gates laying around, youre in luck.

For example, 7411 provides three threeinput nand gates and 7430 provides one eightinput nand gate. Gate universality logic gates electronics textbook. When you begin to build your own digital circuits, you can stock up on integrated circuits that contain just nand gates and. Thus, a logic network that consists of a combination of not, and, and or gates can be created with an equivalent combination of just nand gates. The and, or, not, nand, nor, xor logic gate presentation covers the following. In fact, all boolean functions can be expressed in terms of either nand gates only, or nor gates only.

What is logic gate and, or, xor, not, nand, nor and xnor. You get 4 nand gates, three with 2inputs and one with 3inputs. The nor gate, like the nand gate, nor gate is also useful logical element because it can also be used as a universal gate. The nand boolean function has the property of functional completeness. It is referred to as the universal logic gate chip. How a logic circuit implemented with aoi logic gates can be reimplemented using only nand gates.

Nand and nor are universal gates university of iowa. I dont know how it can be done with 4 2input nand gates. Nand and nor are universal gates any function can be implemented using only nand or only nor gates. In ttl ics using multipleemitter transistors, it also requires fewer transistors than a nor gate. The truth table and symbol of the nor gate is as shown below. Universal gate and nand, nor implementationin hindi.

So any boolean function can be implemented with nandnor gates alone. Jul 08, 2015 nand gates are called universal gates. So it is clear that during the operation of nand gate, the inputs are first going through and gate and after that, the output gets reversed, and we. The small circle bubble at the output of the graphic symbol of a not gate is formally called a negation. This is because, this gate can function as any of the basic logic gates by just making some changes at its input side. At the input side and also at the output side, we are using positive logic, and the absence of bubbles indicates this. Nor gate is the logic gate and is one of the universal gates. Nor gate can be used in combination to perform the and, or and inverter operations. Nand and nor gates are called as universal gates as they can be used to create all other logic gates. We have seen how nand gate can be used to make all the three basic gates by using that alone. Now let us see how each logic gate can be created with nand and nor gates. Between the two levels, we are using negative logic, and the bubbles are used to denote this. Pdf on transformation of a logical circuit to a circuit with nand.

Nor gate will occupy more silicon area than nand gate. Understanding that logic gates can be represented by switches as on off states understanding the different states that can be represented by logic gates understanding that logic gates can be represented by truth tables and boolean expressions. Dec 21, 2014 how to prove that a nand gate is a universal gate by admin in digital electronics, electronics on december 21, 2014. Nand and nor are called universal gates because all the other gates like and,or,not,xor and xnor can be derived from it. Logic gates not, or, and, nor, nand, xor, xnor gate, pdf.

Patel college of engineering and technology subject. The nand gate and nor gates are known as universal gates, since any logic function can be implemented using nand or nor gates. A nor gate is logically an inverted or gate implementation of not gate using nand not made by joining the inputs of a nor gate. A full adder circuit is an arithmetic circuit block that can be used to add three bits to produce a sum and a carry output. Or logic operation can be performed by three nand gates, as shown in fig 6. The above diagrams makes it clear that the combination of nand and nor gates can result into any of the basic gates and, or and not gates.

In fact, you can build all possible logic functions with either just nand gates or just nor gates. Instead, eda tools are used to convert the description of a logical circuit to a netlist of complex gates standard cells or transistors full custom approach. Universal gates in digital electonics nand and nor. As a nor gate is equivalent to an or gate leading to not gate, this automatically sees to the or part of the nor gate, eliminating it from consideration and. Fig 7 depicts the pin diagram of an ic 7400 a ttl, quad 2input nand gate. Digital systems are said to be constructed by using logic gates. Sometimes when youre building circuits, you dont always have the right components. The above diagram is of an or gate made by only using nor gates. For this reason, the nand gate is called a universal gate. On transformation of a logical circuit to a circuit with nand and. At any given moment, every terminal is in one of the two binary conditions false high or true low.

We know that all boolean functions can be expressed in terms of and, or and not. These gates are the and, or, not, nand, nor, exor and exnor gates. Lets see how we can design other gates by using nor gate. Digital circuitsnand logic wikibooks, open books for an. How a nand gate can be used to replace an and gate, an or gate, or an inverter gate. Now we will go over how to build an and gate from nand gates. Most logic gates have two inputs and one output and are based on boolean algebra. Universal gate nand universal gate nand this presentation will demonstrate the basic function of the nand gate. Fortunately when it comes to digital logic gates, you can make the component you need.

For example, it is possible to build a circuit exhibiting the or function using three interconnected nand gates. Lets see why these are preferred and how we can design other gates by using nand gate. The universality of the nand and nor gates means that they can be used as an inverter and the combinations of nand nor gates can be used to implement the and, or, and all other logic operations. That is, given enough gates, either type of gate is able to mimic the operation of any other gate type. So today we will study the complete details on logic gatesnot, or, and, nor, nand, xor, xnor gate, pdf. The output of this gate is exactly similar to that of a single or gate. The nand gate is special because you can use various combinations of nand gates to create and, or, or not gates. A universal gate is a gate which can implement any boolean function without need to use any other gate type. The universal property of nand and nor gates up to this point. Logic nor gate tutorial with logic nor gate truth table. In practice, this is advantageous since nand and nor gates are economical and easier to fabricate and are the basic gates used in all ic digital logic families. This article covers two input logic gates, demonstrates that the nand gate is a universal gate, and demonstrates how other gates are universal gates that can be used to construct any logic gate.

That using a single gate type, in this case nand, will reduce the number of integrated circuits ic required. Generally, nor gate have 2 inputs, lets say x and y, and one output z. For this reason nand and nor are called universal or functionally complete gates. Universal logic gate nor logic gate dyclassroom have.

Jan 04, 2020 now we will look at the operation of nor gates and nand gates as universal gates nand gate as universal gate. Now we will look at the operation of nor gates and nand gates as universal gates nand gate as universal gate. Jul 09, 2015 nor logic gate is called as the universal logic gate. By combining not gate and or gate, nor gate can be constructed. For the second nor gate both the input is equal to r. Here you will get the articles of mechanical engineering in brief with some key points and you will get to know an enormous amount of knowledge from it. So the circuit of figure 159 is interpreted in mixed logic. Lets take a look at the symbol and truth table for or gate first.

Nand and nor gates are called universal gates because all the other gates can be created by using these gates. Introduction to logic gates nand of 11 hardware secrets. Combinational logic using nand and nor gates in this section, you will see how nand and nor gates can be used to implement a logic function. Let us first check an and gate and its truth table and gate truth table. However, i know it can be done if you use a 3input nand gate. This is because any other logic gate on the planet can be made from the right combination of nand gates. Although and,or and not are basic gates but each of their functionality can be derived using nand and not as well. Pdf in the paper we consider fast transformation of a multilevel and multioutput circuit with and, or.

Nand and nor are called universal gates as using only nand or only nor, any logic function can be implemented. So if and, or and not gates can be implemented using nand gates only, then we prove our point. Nor as not this is made by joining the inputs of a nor gate. This article is about nand logic in the sense of building other logic gates using just nand gates.

It contains four 2input nand gates inside a 14pin dip. The ability for a single gate type to be able to mimic any. Two of the input variables and represent the two significant bits to be added and the third input represents the carry from the previous lower significant position. So the circuit of figure 21 is interpreted in mixed logic. That using a single gate type, in this case nand, will reduce the number of integrated circuits ic required to implement a. Very quickly, below are the symbols, boolean expression and truth table of nand and nor gates. Universal gate nand i will demonstrate the basic function of the nand gate.

So if you find this articles helpful, please let us know in the comment box. This gate can function as any of the basic logic gates by just making some changes at its input side. Apr 11, 2016 this video is done by renee sern and tan jia fu, for gek1536 project. When considering gates with more inputs, nor gates requires transistors of 2 different sizes. For nand in the purely logical sense, see logical nand. The fact that the nand notand gate is a universal gate in electronics is incredibly useful because it enables you to build any logic circuit, simple or complex, by using just nand gates. Meaning that you can create any logical boolean expression using only nor gates or only nand gates. Nor gate is used to construct the basic gates similar to and gate. A logic gate is a building block of a digital circuit. There are many articles about how nand and nor are universal gates, but many of these articles omit other gates that are also universal gates. Like nor gates, nand gates are socalled universal gates that can be combined to form any other kind of logic gate. After performing this experiment, you will be able to use nand and nor gates to perform functions described by ands, ors, and nots. To study and verify the truth tables of and, or, not, nand, nor. Sep 18, 2014 proof for nor gates like nand gates, nor gates are socalled universal gates that can be combined to form any other kind of logic gate.

The aim of this paper is to suggest a novel reversible. Logic nor gate tutorial the logic nor gate gate is a combination of the digital logic or gate and an inverter or not gate connected together in series the inclusive nor notor gate has an output that is normally at logic level 1 and only goes low to logic level 0 when any of its inputs are at logic level 1. The first part is an and gate and second part is a dot after it represents a not gate. Learning gates and, or, not, nand, nor, ect and just cant seem to grasp circuit diagrams 9 determining minimum number of nandnor gates required to realize a boolean expression. Universal gate nand and nor gate as universal gates. The karnaugh map eliminates the need for using nand and nor gates.

And, or, not are called basic gates as their logical operation cannot be simplified further. To see this, lets show that nand gates can be used to implement not, and and or. Nand and nor gates are known as universal logic gates, because we can realize any logic circuit or gate only by using nand or nor gates singlehandedly although the logic. And gate the and gate is an electronic circuit that gives a high output 1 only if all its inputs are high. For the love of physics walter lewin may 16, 2011 duration. What links here related changes upload file special pages permanent. Construct the expression fabc with two inverters and a 3input and gate and turn them to nand gates. This article relies largely or entirely on a single source.

Mostly, we prefer nand gates over nor gates for designing the other basic logic gates. Nand gate and nor gate can be used as universal gates because all the basic logic gates can be realized using nand or nor alone as detailed below. The universality of the nand and nor gates means that they can be used as an inverter and the combinations of nandnor gates can be used to implement the and, or, and all other logic operations. The nand gate has the property of functional completeness, which it shares with the nor gate. Considering the figure again, all the transistors in nand gate have equal size where as nor gates dont. The truth table is a tabular representation of a logical expression. The universality of the nand and nor gates means that they can be used as an inverter and the combinations of nandnor gates can be used to implement the and, or, and all. Keywordslogic synthesis, logic devices, vlsi, minimization. Today, integrated circuits are not constructed exclusively from a single type of gate.

Recall from chapter 8 that the nand gate also exhibits an equivalent operation called the negativeor and that the nor gate exhibits an equivalent operation called the negative and. So it is clear that during the operation of nand gate, the inputs are first going through and gate and after that. The not circuit inverts the logic sense of a binary signal. In this tutorial, we are going to learn about the universal logic gates which are nand gate and nor gate. That using a single gate type, in this case nand, will reduce the number of integrated circuits ic required to. A nand gate is a universal gate, meaning that any other gate can be. Logic gates and truth table and, or, not, nor, nand, xor. Proof for nand gates any boolean function can be implemented using and, or and not gates. On the universality of nbit reversible gate libraries.