"Katastrofa! Ten piłkarz nie powinien już grać w kadrze"

[0:00]Hello, good people. My name is Matt, and welcome to this video about the basics of digital logic. Digital logic is probably one of the most fundamental courses that you can take, whether you're interested in computer engineering, computer science, or even electrical engineering. And the reason that I say that is because digital logic is one of the underlying principles to how computers work, all the way down to the processor level. And in this video, we're just going to go over some of the most basic principles of digital logic, that is what is a logic gate, what are the different kinds of logic gates, and what do they do. So let's start with the basic definition. A logic gate is an elementary building block of a digital circuit. Most logic gates have two inputs and one output. At any given moment, every terminal is in one of the two binary conditions, low or high, true or false, zero or one. The binary output of a logic gate is a result of one or more binary inputs. Now that's a pretty textbook definition, but let's take a look at what that actually means. Let's use the example of a light switch. Now, if you want a light to turn on, you have to hit the light switch, right? If you don't hit the light switch, the light will remain off, and if you do hit the light switch, the light will turn on. Simple enough. Now, that is the basic principle of digital logic. You have a certain input, and as a result of that input, you will get a specific output. Now, there are seven basic logic gates, and we're going to go through all of them one by one. The first one is the AND gate. The AND gate is a digital logic gate with n inputs and one output, which performs the logical conjunction. The output of an AND gate is true when all inputs are true. Otherwise, the output is false. Now, let's take a look at a truth table. A truth table is a table that displays all possible input and output combinations of a logic gate. So let's take a look at the truth table of the AND gate. Now, like we said before, the output of an AND gate is true when all inputs are true. So if we have two inputs, input A and input B, and input A is 0 and input B is 0, the output will be 0. If input A is 0 and input B is 1, the output will be 0. If input A is 1 and input B is 0, the output will be 0. And if input A is 1 and input B is 1, the output will be 1. Simple enough. Let's move on to the OR gate. The OR gate is a digital logic gate with n inputs and one output, which performs the logical disjunction. The output of an OR gate is true when at least one input is true. Otherwise, the output is false. Now, let's take a look at the truth table for the OR gate. Like we said before, the output of an OR gate is true when at least one input is true. So if we have input A and input B, and input A is 0 and input B is 0, the output will be 0. If input A is 0 and input B is 1, the output will be 1. If input A is 1 and input B is 0, the output will be 1. And if input A is 1 and input B is 1, the output will be 1. Next up is the NOT gate. The NOT gate is a digital logic gate with one input and one output, which acts as a logical inverter. The output of a NOT gate is true when the input is false, and false when the input is true. Now, let's take a look at the truth table for the NOT gate. As we said before, the output of a NOT gate is true when the input is false, and false when the input is true. So if the input A is 0, the output will be 1. And if the input A is 1, the output will be 0. Next up is the NAND gate. The NAND gate is a digital logic gate with n inputs and one output, which performs the logical NAND function. The output of a NAND gate is false when all inputs are true. Otherwise, the output is true. Now, let's take a look at the truth table for the NAND gate. As we said before, the output of a NAND gate is false when all inputs are true. So if input A is 0 and input B is 0, the output will be 1. If input A is 0 and input B is 1, the output will be 1. If input A is 1 and input B is 0, the output will be 1. And if input A is 1 and input B is 1, the output will be 0. Next up is the NOR gate. The NOR gate is a digital logic gate with n inputs and one output, which performs the logical NOR function. The output of a NOR gate is true when all inputs are false. Otherwise, the output is false. Now, let's take a look at the truth table for the NOR gate. As we said before, the output of a NOR gate is true when all inputs are false. So if input A is 0 and input B is 0, the output will be 1. If input A is 0 and input B is 1, the output will be 0. If input A is 1 and input B is 0, the output will be 0. And if input A is 1 and input B is 1, the output will be 0. Next up is the XOR gate. The XOR gate is a digital logic gate with n inputs and one output, which performs the logical exclusive OR function. The output of an XOR gate is true when exactly one input is true. Otherwise, the output is false. Now, let's take a look at the truth table for the XOR gate. As we said before, the output of an XOR gate is true when exactly one input is true. So if input A is 0 and input B is 0, the output will be 0. If input A is 0 and input B is 1, the output will be 1. If input A is 1 and input B is 0, the output will be 1. And if input A is 1 and input B is 1, the output will be 0. And last but not least, we have the XNOR gate. The XNOR gate is a digital logic gate with n inputs and one output, which performs the logical exclusive NOR function. The output of an XNOR gate is true when all inputs are true or all inputs are false. Otherwise, the output is false. Now, let's take a look at the truth table for the XNOR gate. As we said before, the output of an XNOR gate is true when all inputs are true or all inputs are false. So if input A is 0 and input B is 0, the output will be 1. If input A is 0 and input B is 1, the output will be 0. If input A is 1 and input B is 0, the output will be 0. And if input A is 1 and input B is 1, the output will be 1. And those are the seven basic logic gates. While this is just the tip of the iceberg of what digital logic entails, I hope that this video gave you a basic understanding of what a logic gate is, what are the different kinds of logic gates, and what do they do. Thank you so much for watching, and I'll see you in the next one.