WEBVTT - Electronics 101: Logic Gates 0:00:00.280 --> 0:00:02.960 Brought to you by the reinvented two thousand twelve Camray. 0:00:03.160 --> 0:00:08.840 It's ready. Are you get in touch with technology? With 0:00:09.000 --> 0:00:17.720 tech Stuff from how stuff works dot com. Hello everyone, 0:00:17.760 --> 0:00:20.720 welcome to tex Stuff. My name is Chris Pollette and 0:00:20.760 --> 0:00:23.680 I am an editor how stuff works dot Com, sitting 0:00:23.680 --> 0:00:26.239 across from me, as always his senior writer, Jonathan Strickland, 0:00:26.400 --> 0:00:29.680 logic clearly dictates that the needs of the many outweigh 0:00:29.720 --> 0:00:34.519 the needs of the few. Okay, so today we're going 0:00:34.600 --> 0:00:37.800 to plug Thank you. Today we're gonna talk about logic gates. 0:00:37.840 --> 0:00:40.320 But before we get started, let's let's let's begin with 0:00:40.360 --> 0:00:44.440 a little Facebook feedback you. This comes from James and 0:00:44.520 --> 0:00:49.519 James's suggestion Electronics one oh one logic gates. Thanks James, 0:00:49.720 --> 0:00:52.239 it was an easy one. Yes, we're going to tackle that, 0:00:52.280 --> 0:00:55.360 but before we do, I have a little listener mail. 0:01:00.280 --> 0:01:02.880 This listener mail comes from Chris and not the Chris 0:01:02.920 --> 0:01:05.360 who's sitting across from me. Chris says, you say in 0:01:05.360 --> 0:01:08.200 your three hundred episode that machine code can't be easily 0:01:08.240 --> 0:01:11.440 read by humans. That got me thinking humans made machines. 0:01:11.480 --> 0:01:13.760 I understand that the best concept at the time was 0:01:13.800 --> 0:01:17.760 to code computers and machines with this complicated and unreadable language. 0:01:17.840 --> 0:01:20.240 But in this day and age, why don't we build 0:01:20.280 --> 0:01:23.240 computers and machines that can understand our language. It just 0:01:23.319 --> 0:01:25.640 seems to me that some kind of cycle humans build 0:01:25.720 --> 0:01:28.720 machines that only understand a complicated language, we adapt to 0:01:28.760 --> 0:01:31.319 that language, and we build programs that translate a simpler 0:01:31.400 --> 0:01:34.560 language to the machine language. Is it possible for computers 0:01:34.600 --> 0:01:38.120 and machines to be built to process information in the 0:01:38.200 --> 0:01:42.560 languages we are accustomed to? Now these two items are 0:01:42.600 --> 0:01:46.319 actually related to one another. You might think, well, one 0:01:46.319 --> 0:01:48.200 of these we're talking about natural language, and the other 0:01:48.200 --> 0:01:50.640 one we're talking about logic gates. How do those end 0:01:50.760 --> 0:01:55.160 up being related? Well, it's because machine code is based 0:01:55.240 --> 0:02:00.560 upon the binary system zeros and ones and logics are 0:02:00.680 --> 0:02:04.200 as well. And it turns out that the way we've 0:02:04.200 --> 0:02:09.000 built computers is based upon this binary system, and that's 0:02:09.040 --> 0:02:12.799 why we have machine code. It's this two humans. It's 0:02:12.840 --> 0:02:15.480 a it's a complex way of trying to get a 0:02:15.520 --> 0:02:18.200 machine to do a relatively simple task, or at least 0:02:18.200 --> 0:02:22.400 one that seems simple to us. And unfortunately, there is 0:02:22.480 --> 0:02:27.400 not an easy way to translate natural human language into 0:02:27.480 --> 0:02:30.840 machine code in order to make a machine understand natural 0:02:30.919 --> 0:02:34.720 language in a on a fundamental level, like on a 0:02:34.760 --> 0:02:40.720 mechanical level, we would have to completely change the foundation 0:02:41.000 --> 0:02:45.360 of computing. Yeah, so that's why it's a big deal. Uh. 0:02:45.600 --> 0:02:47.480 You know. Instead, what we do is we end up 0:02:47.480 --> 0:02:53.560 building programs that can understand on on a superficial level 0:02:54.040 --> 0:02:57.360 what natural language is and translated into machine code so 0:02:57.400 --> 0:03:00.560 that a computer can respond the proper way. It's not 0:03:00.680 --> 0:03:04.799 true understanding, because again, a computer is just running processes. 0:03:05.160 --> 0:03:09.440 It's just running, uh, series of calculations using these zeros 0:03:09.440 --> 0:03:13.919 and ones and logic gates are the very foundation of that. 0:03:14.000 --> 0:03:16.880 It's the foundation of circuit treats, the foundation of electronics, 0:03:16.880 --> 0:03:19.720 and the foundation of computers. But it kind of goes 0:03:19.760 --> 0:03:23.079 back a long way back, in fact, before there were 0:03:23.240 --> 0:03:27.320 electronic computers. Oh yeah, I mean, because you know, I 0:03:27.320 --> 0:03:29.400 I think of it as, uh, well, we actually have 0:03:29.600 --> 0:03:33.000 an interesting article about it, um about something that has 0:03:33.040 --> 0:03:36.120 come up with a couple of centuries ago by a 0:03:36.120 --> 0:03:42.560 guy named George. Yeah you know. Oh yes, because logic 0:03:42.600 --> 0:03:46.640 gates operate using Boolean logic, we have then there is 0:03:46.680 --> 0:03:49.280 an article on how Boolean logic works, on how stuff 0:03:49.280 --> 0:03:51.760 works dot com, I recommend actually, which is basically about 0:03:51.760 --> 0:03:55.000 logic gates, which is kind of funny. I had no 0:03:55.080 --> 0:03:59.280 idea until I started doing research on it um because 0:03:59.280 --> 0:04:02.640 we also have a an article about how electronic gates 0:04:02.680 --> 0:04:07.000 work on the the the site. But there's they're sort 0:04:07.040 --> 0:04:08.920 of hand in hand. It's better probably to go back 0:04:08.920 --> 0:04:11.760 through the bully and logic article first and then go 0:04:11.800 --> 0:04:15.640 to the other um. But yeah, I mean, he basically 0:04:15.680 --> 0:04:18.880 figured out how to use uh, you know, I guess 0:04:19.040 --> 0:04:23.280 it's sort of the marriage of language and mathematical operation 0:04:23.720 --> 0:04:26.839 in some ways, wouldn't you say? Yeah? And I also 0:04:27.120 --> 0:04:31.240 tend to to relate it back to symbolic logic, which 0:04:31.279 --> 0:04:35.520 is another way of marrying mathematics with language. Now, if 0:04:35.520 --> 0:04:39.240 you're not familiar, symbolic logic is a concept where you 0:04:39.400 --> 0:04:44.520 reduce statements to sort of almost like an equation, and 0:04:44.640 --> 0:04:48.320 using the equation form, you evaluate that statement to determine 0:04:48.360 --> 0:04:51.640 whether or not the statement or the combination of statements 0:04:51.760 --> 0:04:55.160 is true or faulse um. And you know, you have 0:04:55.240 --> 0:04:58.280 to make some certain assumptions in order to do that, 0:04:58.279 --> 0:05:03.200 but you can build more and more complex equations using 0:05:03.240 --> 0:05:05.920 all these series of statements to determine if the ultimate 0:05:05.960 --> 0:05:09.080 conclusion is true or false, and by true or faulse, 0:05:09.120 --> 0:05:13.280 we're really talking about whether the argument holds water or not. 0:05:13.680 --> 0:05:16.200 So you can actually do this. You could take a 0:05:16.279 --> 0:05:19.680 debate and you could take one person's side of the debate, 0:05:20.040 --> 0:05:23.720 reduce it to this sort of mathematical equation, and then 0:05:23.800 --> 0:05:27.359 determine whether or not the ultimate outcome of that of 0:05:27.440 --> 0:05:30.599 that person's side of the debate makes sense from a 0:05:30.680 --> 0:05:34.520 logical standpoint. Yeah. Now again we're talking logic here. We're 0:05:34.520 --> 0:05:38.760 not talking about, uh, you know, trying to get someone 0:05:38.839 --> 0:05:42.359 to agree to something based upon its emotional weight, but 0:05:42.600 --> 0:05:45.680 simply does this argument makes sense? Does it follow the 0:05:45.760 --> 0:05:49.160 rules of logic? Yeah? And a lot of these UM 0:05:49.240 --> 0:05:52.880 when we talk about the logic gates UM, they're actually 0:05:52.880 --> 0:05:59.479 devices inside electronics that use these logical operators, these rules, 0:05:59.520 --> 0:06:04.520 these rules within the machine. Basically, they're passing instructions based 0:06:04.560 --> 0:06:06.520 on the type of circuit they are and according I 0:06:06.600 --> 0:06:09.479 actually look this up in Access Science, which is UM 0:06:09.600 --> 0:06:14.040 a really awesome database for for technical things like this. UM. Basically, 0:06:14.080 --> 0:06:17.279 the Access Science said that if you're creating a gate 0:06:17.320 --> 0:06:20.520 circuit UM, they could be made up of transistors, diodes, 0:06:20.600 --> 0:06:24.680 or resistors, in some combination. Now most today are are 0:06:24.720 --> 0:06:27.920 generally transistors only, but they could be made up a 0:06:28.000 --> 0:06:32.240 variety of components um and they're they're basically, you know, 0:06:32.560 --> 0:06:35.080 you hook these up, and you can hook them up 0:06:35.080 --> 0:06:37.400 in a variety of different ways depending on the type 0:06:37.400 --> 0:06:39.480 of device and what you're trying to get it to do. 0:06:40.320 --> 0:06:43.839 Um it. We'll get into that later, but basically, these 0:06:43.920 --> 0:06:48.520 circuits are um a series of components that are wired 0:06:48.520 --> 0:06:52.920 together to perform a logical operation within a device. So 0:06:53.040 --> 0:06:56.200 let's start off from the very very very basic steps. 0:06:56.320 --> 0:07:02.760 So it all begins with bits, zeros, and ones. Now 0:07:03.880 --> 0:07:06.919 this these aren't just numbers zero and one does not 0:07:07.120 --> 0:07:10.440 that doesn't that to us, That doesn't really mean anything 0:07:10.440 --> 0:07:13.200 other than the fact that we can do mathematical processes 0:07:13.400 --> 0:07:17.400 using them. As as as values zero and one um 0:07:17.440 --> 0:07:23.040 they actually translate into other concepts. So a zero in 0:07:23.080 --> 0:07:28.760 an electronics system would be a low voltage meaning zero volts, 0:07:28.880 --> 0:07:31.680 and a one is high voltage, meaning five volts. So 0:07:31.720 --> 0:07:34.760 a one means you've got electrons running through there at 0:07:34.760 --> 0:07:37.320 five vaults. Zero means there are no electrons running through 0:07:37.400 --> 0:07:42.160 zero vaults. But a zero also would mean a false statement. 0:07:43.080 --> 0:07:46.000 One means a true statement. Zero could also be thought 0:07:46.000 --> 0:07:48.880 of as being on in the off position. One is 0:07:48.920 --> 0:07:54.040 in the on position. So let's we have to do. 0:07:54.080 --> 0:07:56.280 You know, zero and one is kind of shorthand of saying. 0:07:56.280 --> 0:07:58.320 So if we're talking about zeros, we're talking about false, 0:07:58.560 --> 0:08:00.240 and we're talking about once, we're talking about true. For 0:08:00.240 --> 0:08:02.120 time about zero's we're talking about low voltage. If we're 0:08:02.120 --> 0:08:04.480 talking about one, we're talking about high voltage. This is 0:08:04.480 --> 0:08:11.080 how we translate ideas conceptually into a real device, a 0:08:11.120 --> 0:08:16.200 physical device that does something one there we go true. 0:08:16.640 --> 0:08:21.280 So now a logic gate will process a signal and 0:08:21.920 --> 0:08:24.240 what it does to that signal, like it has an 0:08:24.240 --> 0:08:27.320 input and an output, what it does to that signal 0:08:27.360 --> 0:08:30.120 when it comes in through the input is based upon 0:08:30.240 --> 0:08:33.400 two things. The nature of the logic gate, because there 0:08:33.400 --> 0:08:37.880 are several different basic types of logic gates, and the 0:08:37.920 --> 0:08:41.240 whether or not the input was true or false, so 0:08:41.320 --> 0:08:43.120 whether or not it was a one or a zero. 0:08:44.120 --> 0:08:47.920 Those two elements will determine what the output of that 0:08:48.000 --> 0:08:52.080 specific logic gate is. And the simplest logic gate is 0:08:52.120 --> 0:08:55.800 a not git that's also known as an inverter. Yes, 0:08:56.040 --> 0:08:58.480 Now inverters what they do is, they will take an 0:08:58.520 --> 0:09:02.600 input and switch it to the opposite output. So, in 0:09:02.640 --> 0:09:07.080 other words, if a zero is fed into a not gate, 0:09:07.240 --> 0:09:10.640 it will produce a one. So false statement comes into 0:09:10.640 --> 0:09:12.880 a not gate, it flips it to a true statement 0:09:12.920 --> 0:09:17.320 coming out right, all right, so or against low voltage 0:09:17.360 --> 0:09:20.320 to high voltage, yes, vice versa. So whatever the signal 0:09:20.360 --> 0:09:25.000 coming into the the not gate is, the opposite goes out. 0:09:25.800 --> 0:09:28.840 Now it can only have one input, which makes it 0:09:28.960 --> 0:09:32.760 unique among the gates. The other gates have two or 0:09:32.880 --> 0:09:35.560 more inputs, and they combine the two in order to 0:09:35.559 --> 0:09:40.160 produce a result. Alright, So then the next one would 0:09:40.200 --> 0:09:45.080 be an and gate. Now and gates will produce a 0:09:45.120 --> 0:09:49.600 true result only if both inputs coming into the gate 0:09:49.679 --> 0:09:52.920 are also true. I think of that like the programming 0:09:52.920 --> 0:09:57.360 statement if then if both are true, then it will 0:09:57.400 --> 0:10:01.679 return true results. So that means that let's say imagine 0:10:01.679 --> 0:10:04.280 that you have this. You can actually imagine that this 0:10:04.360 --> 0:10:06.600 is a gate and there are two roads leading into 0:10:06.600 --> 0:10:09.000 the gate, and you have two cars going up to 0:10:09.120 --> 0:10:14.520 the gate. If both cars are are true, then you've 0:10:14.559 --> 0:10:16.440 got a true result coming out. Otherwise you have a 0:10:16.440 --> 0:10:18.760 false result coming out. Actually, it would be and if 0:10:18.880 --> 0:10:22.240 and only if yes. So, in other words, if you 0:10:22.320 --> 0:10:26.000 have to If you have these two uh inputs coming 0:10:26.000 --> 0:10:29.520 into the and gate and both are a one, so 0:10:29.600 --> 0:10:32.320 both are true, both are high voltage, you get a 0:10:32.320 --> 0:10:34.920 one as a result. Any other combination you get a 0:10:35.040 --> 0:10:38.640 zero as a result a false statement or low voltage. 0:10:38.880 --> 0:10:42.280 Zero and one will equal zero. In this case, zero 0:10:42.400 --> 0:10:45.160 zero will be zero, zero one will be zero, one 0:10:45.320 --> 0:10:47.960 zero will be zero because you have to think of 0:10:48.080 --> 0:10:51.920 all three instances that way. Even though you might say, wait, 0:10:52.000 --> 0:10:54.160 zero one and one zero, isn't that the same thing? No, 0:10:54.360 --> 0:10:57.520 Because you're talking about two different inputs coming into a gate, 0:10:58.240 --> 0:11:00.960 and those two inputs are coming from two different sources. 0:11:01.000 --> 0:11:04.120 Sometimes yeah, sometimes they come from the same source, but 0:11:04.200 --> 0:11:07.000 usually they come from two different sources. And that means 0:11:07.080 --> 0:11:09.720 that because they're coming from two different sources, you have 0:11:09.760 --> 0:11:12.200 two different configurations. You have one where one is true 0:11:12.240 --> 0:11:14.280 and one is faults, and another one where one is 0:11:14.320 --> 0:11:17.120 faults and the other is true. Sounds kind of complicated, 0:11:17.160 --> 0:11:19.480 it's actually pretty simple. And again, if this starts to 0:11:19.600 --> 0:11:22.040 sound confusing, check out these articles that we have on 0:11:22.040 --> 0:11:26.120 our site because they will help illustrate these concepts. So, 0:11:26.480 --> 0:11:29.440 besides the end gate, you have the nand gate or 0:11:29.520 --> 0:11:33.960 not and now and not and will produce a true 0:11:34.000 --> 0:11:38.560 result in every case except where both inputs or more 0:11:38.679 --> 0:11:41.160 are true, because you can have more than two inputs 0:11:41.240 --> 0:11:44.080 in an end or a nand gate. So in other words, 0:11:44.200 --> 0:11:46.960 if you have two zeros, a zero, one, or a 0:11:47.000 --> 0:11:49.360 one zero, you're gonna get a one out of a 0:11:49.440 --> 0:11:52.200 nand gate. If it's a one and one, it's going 0:11:52.240 --> 0:11:55.400 to come out as a zero in a nand gate, right, 0:11:56.120 --> 0:11:59.200 Then you've got the or gate, and or gate will 0:11:59.240 --> 0:12:02.640 produce a true result if at least one of the 0:12:02.720 --> 0:12:07.400 inputs is true, so zero, one, one, zero, and one 0:12:07.440 --> 0:12:10.720 one will all produce a one. Only zero zero produces 0:12:10.760 --> 0:12:13.960 a zero or a false statement. Then you've got the 0:12:14.040 --> 0:12:16.800 Nora gate, which is not or It will produce a 0:12:16.800 --> 0:12:20.520 true result if both inputs are false, so zero zero 0:12:20.679 --> 0:12:23.920 will produce a one zero, one one zero and one 0:12:23.920 --> 0:12:27.839 one will produce a zero. Then you have now all 0:12:27.880 --> 0:12:31.040 of those gates, the the and nand or and nor 0:12:31.160 --> 0:12:35.000 gates can receive multiple inputs. And in order to really 0:12:35.040 --> 0:12:37.199 kind of sort this out, I know it sounds confusing, 0:12:37.440 --> 0:12:40.680 you can actually build a truth table. A truth table 0:12:40.720 --> 0:12:43.319 is essentially just a it's like it's almost like a spreadsheet, 0:12:43.600 --> 0:12:47.880 and it shows you what each scenario, what the outcome 0:12:47.960 --> 0:12:51.280 would be for that particular scenario for that particular gate. 0:12:52.280 --> 0:12:55.680 So like if A equal zero and be equal zero, 0:12:56.120 --> 0:13:00.480 results C will equal whatever I should say result Q 0:13:00.679 --> 0:13:05.120 because that's typically how they label it in uh in diagrams. Yeah, 0:13:05.280 --> 0:13:08.120 they usually use a que to differentiate, so there's no 0:13:08.160 --> 0:13:11.360 confusion that it's zero. They they you use a que 0:13:11.400 --> 0:13:14.319 so that you get the ideas. Oh yeah, that's the output. 0:13:14.960 --> 0:13:17.400 Um yeah, I was just gonna say that truth table 0:13:17.480 --> 0:13:20.640 kind of sounds like a medieval torture device. Him on 0:13:20.760 --> 0:13:28.320 the truth table, nobody resists the machine. I really don't 0:13:28.320 --> 0:13:31.199 know what that would do to you. Um Now I 0:13:31.320 --> 0:13:34.000 just quote Princess Bride, but of this, I was gonna 0:13:34.040 --> 0:13:37.720 say that there's an extra bonus movie quote. Remember this 0:13:37.840 --> 0:13:41.640 is for posterity, so please be honest. There are two 0:13:41.640 --> 0:13:44.360 more gates. Two more gates. Yes, there's X or the 0:13:44.400 --> 0:13:48.000 exclusive or gate, which produces a true result if the 0:13:48.040 --> 0:13:51.760 two inputs are different. So if a zero, zero or 0:13:51.840 --> 0:13:54.080 one one comes into an ex or gate, you're gonna 0:13:54.080 --> 0:13:56.560 get a zero, right if you get a if it's 0:13:56.600 --> 0:13:59.840 one zero or zero, one going into an ex orgate 0:14:00.080 --> 0:14:03.600 get a one. Uh. Now, because of the nature of 0:14:03.640 --> 0:14:07.080 this gate, it can only accept two inputs. You cannot 0:14:07.200 --> 0:14:10.640 you cannot have multiple inputs beyond two in an x 0:14:10.760 --> 0:14:14.080 or gate because it has to be specifically geared that way. Right, 0:14:14.160 --> 0:14:17.800 because because it has to be if it if it's if, 0:14:17.840 --> 0:14:20.800 if they have to be different. Uh, then there are 0:14:20.840 --> 0:14:23.400 only two choices, right, there's a zero, there's a one. 0:14:24.040 --> 0:14:26.680 If you have three inputs going into something and they 0:14:26.720 --> 0:14:28.640 have to be different and there's only two choices, there's 0:14:28.640 --> 0:14:30.760 no way two of those inputs have to be the same. 0:14:31.560 --> 0:14:35.320 Bye bye again following logic. So therefore, and an ex 0:14:35.480 --> 0:14:38.600 or gate, only two inputs can go into that gate. 0:14:38.840 --> 0:14:41.920 Then you have the x nore gate and it produces 0:14:41.960 --> 0:14:44.400 a true result if both inputs are the same. So 0:14:44.480 --> 0:14:46.960 if a zero zero or a one one goes into 0:14:47.000 --> 0:14:49.600 an exnore gate, you get a one. Otherwise you get 0:14:49.600 --> 0:14:51.880 a zero. Same thing as the ex or gate in 0:14:51.880 --> 0:14:56.360 that you can only have two inputs going into that gate. Now, 0:14:57.760 --> 0:15:00.720 using these gates that we have just described here, if 0:15:00.760 --> 0:15:04.160 you build you can actually build up a circuit using 0:15:04.200 --> 0:15:06.800 those as their basic building blocks. In fact, you can 0:15:06.840 --> 0:15:09.360 go to a hobby store and buy chips that have 0:15:09.520 --> 0:15:13.440 logic gates built onto them. Yes, and we were talking 0:15:13.440 --> 0:15:17.480 about the the RDU know a few weeks ago, And 0:15:17.560 --> 0:15:20.000 these are the kinds of projects now if you can 0:15:20.040 --> 0:15:21.880 get a basic grip on this, these are the kinds 0:15:21.880 --> 0:15:23.800 of things that you can add to your projects if 0:15:23.840 --> 0:15:28.080 you're doing um hobbies yourself and want to do this. Now, 0:15:28.440 --> 0:15:30.000 you know, once you get a basic understanding of this, 0:15:30.120 --> 0:15:33.240 you can make much more complex projects. Yeah, so, uh 0:15:33.400 --> 0:15:36.760 you know, we you can consider building a circuit using 0:15:36.800 --> 0:15:40.400 this as as using combinational logic. You're combining various gates 0:15:40.400 --> 0:15:43.120 together in order to get a different results. So you 0:15:43.200 --> 0:15:46.560 might have three inputs going into a system, and then 0:15:46.600 --> 0:15:50.600 you you align various gates in a very in a 0:15:50.640 --> 0:15:54.080 particular sequence in order to get a different result, and 0:15:54.920 --> 0:15:58.040 it all will obey the laws of the truth tables. Now, 0:15:58.080 --> 0:16:01.560 these these circuits can get pretty lunkey and pretty complex, 0:16:01.600 --> 0:16:05.160 which is why we've sort of abandoned the uh you know, 0:16:05.400 --> 0:16:08.080 it works great as a concept. In reality, we've virtualized 0:16:08.120 --> 0:16:10.520 a lot of this since then because it just otherwise 0:16:10.520 --> 0:16:12.800 it would just be a massive piece of hardware in 0:16:12.880 --> 0:16:16.680 order to build a really really complex circuit um. But 0:16:16.840 --> 0:16:20.080 you you can actually lay these out in various configurations 0:16:20.080 --> 0:16:23.160 to get different results. So it might you might have 0:16:23.400 --> 0:16:28.680 uh two inputs going into and and UH gate and 0:16:28.720 --> 0:16:32.000 another input going into a not gate, and then those 0:16:32.080 --> 0:16:36.000 the results of those um of those particular functions will 0:16:36.040 --> 0:16:39.400 go into a third gate and then now that way 0:16:39.440 --> 0:16:41.680 you have something coming out like maybe the maybe those 0:16:41.720 --> 0:16:44.560 are both going into an ex or gate, and then 0:16:44.600 --> 0:16:48.800 whatever the result is is what you're looking for. Uh. These, 0:16:50.000 --> 0:16:52.440 like I said, get pretty clunky pretty fast. The interesting 0:16:52.440 --> 0:16:56.320 thing is you can actually replace the function of some 0:16:56.400 --> 0:16:58.800 of these gates using other gates. You just have to 0:16:58.880 --> 0:17:02.280 put them in the right configu duration to do so. 0:17:02.280 --> 0:17:03.720 So you can think of some of these gates is 0:17:03.720 --> 0:17:06.360 almost being like shorthand like this gate does this one 0:17:06.480 --> 0:17:10.159 function and so therefore uh it does it um. You know, 0:17:10.200 --> 0:17:12.720 that's all it does. You just put that in this place. 0:17:12.760 --> 0:17:15.640 But sometimes you might be working with a system where 0:17:15.640 --> 0:17:18.560 you don't want to have lots of different types of gates. 0:17:18.800 --> 0:17:21.200 You want to use maybe one or two types of 0:17:21.240 --> 0:17:22.760 gates and you don't want to have to deal with 0:17:22.800 --> 0:17:25.199 all the others. Well you can do that. You just 0:17:25.280 --> 0:17:28.320 have to build the gates in the proper sequence in 0:17:28.440 --> 0:17:31.520 order to get the result you want, UH for it 0:17:31.560 --> 0:17:34.320 to to copy the function of one of the other gates. 0:17:34.359 --> 0:17:36.600 And there's various ways of doing this. Now, it does 0:17:36.680 --> 0:17:40.520 mean that you're going to use more gates overall usually 0:17:41.000 --> 0:17:43.600 than you would if you were using the the different types, 0:17:43.640 --> 0:17:46.560 but you would all be using the same type of gates. 0:17:46.560 --> 0:17:49.280 So you're you've reduced it to a single type of gate, 0:17:49.600 --> 0:17:52.400 but you you're using more of that particular gate than 0:17:52.440 --> 0:17:54.800 you would if you were using multiple types of gates. 0:17:55.960 --> 0:17:59.080 Sounds a little complicated, but it does. It does mean 0:17:59.119 --> 0:18:02.240 that when you're sketching it out, it really cuts down 0:18:02.320 --> 0:18:04.440 on the sort of gates that you have to design 0:18:04.800 --> 0:18:08.520 when you're when you're at least conceptually building your circuitry. Now, 0:18:10.160 --> 0:18:12.840 go ahead, and I was just gonna say that these 0:18:12.920 --> 0:18:16.919 these gates can be run in parallel or in a series, 0:18:17.280 --> 0:18:20.040 and um it actually kind of reminds me in a 0:18:20.080 --> 0:18:25.399 way of a very complex UH railway, because I mean, 0:18:25.440 --> 0:18:28.560 you're basically using these switches to control the flow of 0:18:28.600 --> 0:18:35.199 information in your electronic device. Um So as a you know, 0:18:35.240 --> 0:18:37.879 as someone would watch the board and make sure that 0:18:37.880 --> 0:18:41.840 the trains don't collide. Um. You're also sort of you know, 0:18:41.960 --> 0:18:44.960 you can actually control the way information flows through the 0:18:45.520 --> 0:18:48.000 device using these switches, and you can place them in 0:18:48.040 --> 0:18:51.680 ways that make the most sense to to what you're 0:18:51.680 --> 0:18:53.800 trying to carry out, which is essentially what you just said. 0:18:53.800 --> 0:18:58.359 But um, it helps me think about this conceptually, to 0:18:58.880 --> 0:19:02.080 put it in and out analogy from that to something 0:19:02.119 --> 0:19:04.560 that I can think about, like trains, because trains are 0:19:04.640 --> 0:19:06.800 nice and and if you wanna, you know, if you 0:19:06.800 --> 0:19:09.199 really want to get into this, each of these gates 0:19:09.240 --> 0:19:15.840 has a particular um graphical representation of you know, what 0:19:15.960 --> 0:19:19.280 it does. So it's I'm not bothering describing it on 0:19:19.320 --> 0:19:21.280 the podcast because this is an audio podcast. It would 0:19:21.320 --> 0:19:23.280 be kind of it would be kind of pointless to 0:19:23.320 --> 0:19:25.800 do it. And the shapes, the shapes aren't you know, 0:19:26.280 --> 0:19:29.040 like a circle or a triangle or a square something 0:19:29.080 --> 0:19:32.679 that is uh easy to describe, a lot of these 0:19:32.680 --> 0:19:35.920 shapes are modifications of those types of things. So you 0:19:36.000 --> 0:19:38.480 might say a trianglar looking thing, but you're really not 0:19:38.520 --> 0:19:40.840 going to get it. It makes more sense to actually 0:19:40.840 --> 0:19:43.200 go to a website that has them all laid out, 0:19:43.520 --> 0:19:46.639 and then once you learn what the the sort of 0:19:46.760 --> 0:19:50.119 graphic representation of a gate what it looks like. You 0:19:50.160 --> 0:19:54.359 can start looking at um the combination of gates and say, oh, 0:19:54.400 --> 0:19:56.920 well that's an and gate. So that means that since 0:19:56.960 --> 0:20:00.560 I know that and gates always give a result, that is, 0:20:00.760 --> 0:20:02.959 it will produce a true result only if both inputs 0:20:03.000 --> 0:20:05.159 are true. I know what the output of this end 0:20:05.200 --> 0:20:08.080 gate will be depending upon the inputs. So, because it's 0:20:08.080 --> 0:20:10.400 always going to behave the same way, it's never going 0:20:10.440 --> 0:20:13.959 to behave uh in a way opposite or different unless 0:20:13.960 --> 0:20:17.040 you you know, well never, it will never do that. 0:20:17.320 --> 0:20:19.080 It's only if you were using a nand gate that 0:20:19.119 --> 0:20:23.440 it would be different than the way it normally is. UM. 0:20:23.560 --> 0:20:26.880 So that way, since you know how each gate behaves 0:20:26.920 --> 0:20:32.000 in any specific circumstance given time, you can decipher what 0:20:32.240 --> 0:20:35.800 a fairly complex diagram will do. You just say, all right, 0:20:35.920 --> 0:20:39.200 I know that this gate always behaves this way. Therefore, 0:20:39.960 --> 0:20:44.480 this is what would happen given this particular series of inputs. 0:20:44.920 --> 0:20:47.119 You can actually build out a truth table for a 0:20:47.119 --> 0:20:50.199 complex circuit that way, and you will ultimately know what 0:20:50.359 --> 0:20:55.080 the circuit will produce given any particular set of circumstances. Now, 0:20:55.119 --> 0:20:57.680 the more complex a circuit gets the wider that truth 0:20:57.720 --> 0:20:59.800 table is gonna be, and the more you're gonna have 0:20:59.840 --> 0:21:02.480 to really check to make sure you're following the logical 0:21:02.560 --> 0:21:07.400 rules so that the results are are accurate, um other 0:21:07.520 --> 0:21:10.600 and we call this, we actually call this programming a circuit. 0:21:10.720 --> 0:21:13.320 Even though you might think of programming is something you 0:21:13.359 --> 0:21:17.199 do sitting down typing on a keyboard. This and this 0:21:17.240 --> 0:21:21.879 involves actual physically hooking up wires to logic gates in 0:21:21.920 --> 0:21:25.359 whatever sequence or series you need. Uh, we still call 0:21:25.400 --> 0:21:28.320 that programming. Yeah, an engineer might graft this out using 0:21:28.359 --> 0:21:31.119 these symbols on a piece of paper to get an 0:21:31.160 --> 0:21:33.959 idea of how it works. But logic gates can be 0:21:34.080 --> 0:21:36.480 very very small. I mean, we're we we've talked about 0:21:36.520 --> 0:21:39.240 the manufacture of transistors before. I mean, you can have 0:21:39.960 --> 0:21:43.840 millions of transistors and a very small piece of silicon 0:21:44.600 --> 0:21:48.320 and the logic gates I mean, using the metal oxide 0:21:48.359 --> 0:21:53.040 semiconductor UH type, which is apparently predominant according to Access 0:21:53.040 --> 0:21:56.840 Science and manufacturing today, you can have many, many of 0:21:56.880 --> 0:21:59.399 these devices. So it helps I mean, I think it 0:21:59.400 --> 0:22:01.280 would help me if I were trying to figure out 0:22:01.320 --> 0:22:03.960 exactly how I wanted to lay out this device to 0:22:04.080 --> 0:22:06.399 have it you know, drafted out with these symbols and 0:22:06.440 --> 0:22:08.399 get an idea of how it's it's working. I'm sure 0:22:08.440 --> 0:22:11.440 a lot of them use computers. Actually have a program 0:22:11.440 --> 0:22:15.400 that I use for information architecture that has a template 0:22:15.440 --> 0:22:17.160 with all these symbols on there, and then you can, 0:22:17.200 --> 0:22:18.600 you know, put it up on the screen and get 0:22:18.640 --> 0:22:20.760 an idea of how it works. But that's far larger 0:22:20.800 --> 0:22:24.280 than the actual devices because the manufacturing process can make 0:22:24.280 --> 0:22:26.800 them very very tiny, right, And as we've said in 0:22:26.920 --> 0:22:31.040 other podcasts, this is part of why miniaturization has some 0:22:31.400 --> 0:22:34.760 uh some challenges, uh that go along with it. I mean, 0:22:34.760 --> 0:22:36.320 there are a lot of different challenges, but one of 0:22:36.320 --> 0:22:39.359 the challenges is that by getting these gates to be 0:22:39.480 --> 0:22:42.720 smaller and smaller, each each element on a transistor is 0:22:42.800 --> 0:22:46.240 decreasing in size. Remember, if we're following Moore's law, then 0:22:46.280 --> 0:22:48.320 ideally you're going to be able to fit twice as 0:22:48.359 --> 0:22:51.840 many discrete elements on a chip within twenty four months, 0:22:51.920 --> 0:22:54.960 or at least the the number of discrete elements on 0:22:55.000 --> 0:22:56.800