For example, it is possible to build a circuit exhibiting the or function using three interconnected nand gates. This is because, this gate can function as any of the basic logic gates by just making some changes at its input side. 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. To study the realization of basic gates using universal gates. Its output depends upon the combination of inputs and previously stored bit. Universal gates in digital electonics nand and nor. For the second nor gate both the input is equal to r. An entire processor can be created using nand gates alone. The nand or nor gates are referred to as universal gates. The nand gate and nor gates are known as universal gates, since any logic function can be implemented using nand or nor gates. After performing this experiment, you will be able to use nand and nor gates to.
Nand and nor gates are called universal gates because all the other gates can be created by using. When an input or output line on a logic circuit symbol has no bubble on it, that line is said to be activehigh. Logic gates not, or, and, nor, nand, xor, xnor gate, pdf. So we can see that all the three basic gates can be made by only using nand gates, thats why this gate is called universal gate, and it is appropriate. Computer system logic and control gates tutorial pdf. Logic and control gates describe the basic logical procedures and logical system of computer system. Nand not and, nor not or, xor, and xnor not xor later a b out 0 0 0 0 1 1 1 0 1 1 1 1. Nand gate, we can build the three basic logic operators.
A similar case applies to the nor function, and this is referred to as nor logic. Ttl open collector nand gate youtube tutorial 2 vlsi electric full adder layout design youtube gate array wikipedia cardinal bird quotes and sayings. Patel college of engineering and technology subject. To implement the basic gates, we have applied the implementations of nand and nor using qca. The nand and nor gates are the complements of the previous and and or functions respectively and are individually a complete set of logic as they can be. Universal gate nand universal gate nand this presentation will demonstrate the basic function of the nand gate. The output of the first nand is the second input to the other two. How to draw a nand gate using only nor gates quora. Finally, another nand takes the outputs of these two nand gates to give the final output. Cmos wikipedia nand gate physics hyper using a nand or nor gate as a not.
Understanding how to construct any combinational logic function using nand or nor gates only. A nand gate is a universal gate, meaning that any other gate can be. Digital logic basics 21 implementation using nand gates. An sr set, reset latch is a digital storage device. Implementing logic functions using only nand or nor gates. The above diagram is of an or gate made by only using nor gates. 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. And, or, not are called basic gates as their logical operation cannot be. Pdf realization of basic gates using universal gates using. Components and design techniques for digital systems spring 2014 ck cheng, diba mirza dept.
Nand and nor are universal gates university of iowa. 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. From switches to transistors, logic gates and logic circuits hakim weatherspoon cs 3410, spring 20 computer science cornell university. Meaning that you can create any logical boolean expression using only nor gates or only nand gates. In fact, all boolean functions can be expressed in terms of either nand gates only, or nor gates only. Digital logic circuits in yeast with crisprdcas9 nor gates. No 3 universality of nand nor gates nand gate nor gate. Nand and nor gates are easier to fabricate with electronic components and are the basic gates used. When considering gates with more inputs, nor gates requires transistors of 2 different sizes whose size difference is more when comparing with nand gates. Taken to limit, give me as many nand gate as i want, in theory i can build a pentium processor. 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. So if you find this articles helpful, please let us know in the comment box, either if any. Digital circuit are frequently constructed with nand or nor gates rather than and and or gates. We have seen how nand gate can be used to make all the three basic gates by using that alone.
Nand and nor gates are called as universal gates as they can be used to create all other logic gates. For example, the function notx may be equivalently expressed as nandx,x. So if and, or and not gates can be implemented using nand gates only, then we prove our point. Gate universality nand and nor gates possess a special property. Mostly, we prefer nand gates over nor gates for designing the other basic logic gates. Universal gates are defined as which logic gates can implement any types logic gates. Considering the figure again, all the transistors in nand gate have equal size where as nor gates dont. So, we feed a and b as input to the first nor gate. That is, given enough gates, either type of gate is able to mimic the operation of anyother gate type. So today we will study the complete details on logic gates not, or, and, nor, nand, xor, x nor gate, pdf. The basic logic gates arethe inverter or not gate, the. The above diagram is of an and gate made from nand gate. Nor gate is the logic gate and is one of the universal gates. The nand boolean function has the property of functional completeness.
When you begin to build your own digital circuits, you can stock up on integrated. The nand gate and the nor gate can be said to be universal gates since combinations of them can be used to accomplish any of the basic operationsand can thus produce an inverter, an or gate or an and gate. Steps to apply superposition 8 1 turn off all independent sources except one. Universal logic gate nor logic gate dyclassroom have. Nand and nor gates are easier to fabricate with electronic components and are the basic gates used in all ic digital logic families. A universal gate is a gate which can implement any boolean function without need to use any other gate type. Nor gate is used to construct the basic gates similar to and gate. Pdf on transformation of a logical circuit to a circuit with nand.
An sr latch can be constructed by using two cross couples nand nor gates. As a result, we can build any logic circuit and implement any boolean expression. Nor gates are socalled universal gates that can be combined to form any other kind of logic gate. Very quickly, below are the symbols, boolean expression and truth table of nand and nor gates. And, or, xor, not, nand, nor and xnor are popular examples for logical gates. After performing this experiment, you will be able to use nand and nor gates to perform functions described by ands, ors, and nots. The figure shows a combination of two not gates and a nor gate. By combining not gate and or gate, nor gate can be constructed. That is, given enough gates, either type of gate is able to mimic the operation of any other gate type. In fact, an and gate is typically implemented as a nand gate.
To demonstrate the operation and characteristics of nand and nor gates and to show how any of these gates can be used to perform any of the three basic logic functions. Just connect another not using nand to the output of an or using nand. We know that all boolean functions can be expressed in terms of and, or and not. You will be able to prove the universality of nand and nor gates. For example, it is possible to build a circuit exhibiting the or.
In the field of digital electronic circuits, this implies that we can implement any boolean function using just nand gates. Universal gate nand and nor gate as universal gates. To see this, lets show that nand gates can be used to implement not, and and or. Verify the functionally of the nand and nor gates by developing their truth table.
For vlsi technologies, all gates are inverted and,or operation with a bubble at output. This means, any boolean expression can be reexpressed by an equivalent expression utilizing only nand operations. Although and,or and not are basic gates but each of their functionality can be derived using nand and not as well. The noninverting gates do not have this versatility since they cant produce an invert. 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. Universal logic gates and complete sets basic electronics tutorials. Nand and nor are called universal gates because all the other gates like and,or,not,xor and xnor can be derived from it. How a nand gate can be used to replace an and gate, an or gate, or an inverter gate. The output of this gate is exactly similar to that of a single or gate. How a logic circuit implemented with aoi logic gates. Gate universality logic gates electronics textbook. In ttl ics using multipleemitter transistors, it also requires fewer transistors than a nor gate.
915 574 851 1256 194 1316 985 820 1424 162 946 1459 312 1488 357 1315 1089 914 1456 541 830 822 873 475 905 225 217 284 1048 1310 151 1222 225 1168 1033 504 1048 1352 374 695 178