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Speaker 1: Brought to you by the reinvented two thousand twelve Camray.

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Speaker 1: It's ready. Are you get in touch with technology? With

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Speaker 1: tech Stuff from how stuff works dot com. Hello everyone,

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Speaker 1: welcome to tex Stuff. My name is Chris Pollette and

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Speaker 1: I am an editor how stuff works dot Com, sitting

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Speaker 1: across from me, as always his senior writer, Jonathan Strickland,

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Speaker 1: logic clearly dictates that the needs of the many outweigh

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Speaker 1: the needs of the few. Okay, so today we're going

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Speaker 1: to plug Thank you. Today we're gonna talk about logic gates.

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Speaker 1: But before we get started, let's let's let's begin with

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Speaker 1: a little Facebook feedback you. This comes from James and

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Speaker 1: James's suggestion Electronics one oh one logic gates. Thanks James,

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Speaker 1: it was an easy one. Yes, we're going to tackle that,

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Speaker 1: but before we do, I have a little listener mail.

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Speaker 1: This listener mail comes from Chris and not the Chris

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Speaker 1: who's sitting across from me. Chris says, you say in

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Speaker 1: your three hundred episode that machine code can't be easily

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Speaker 1: read by humans. That got me thinking humans made machines.

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Speaker 1: I understand that the best concept at the time was

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Speaker 1: to code computers and machines with this complicated and unreadable language.

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Speaker 1: But in this day and age, why don't we build

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Speaker 1: computers and machines that can understand our language. It just

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Speaker 1: seems to me that some kind of cycle humans build

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Speaker 1: machines that only understand a complicated language, we adapt to

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Speaker 1: that language, and we build programs that translate a simpler

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Speaker 1: language to the machine language. Is it possible for computers

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Speaker 1: and machines to be built to process information in the

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Speaker 1: languages we are accustomed to? Now these two items are

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Speaker 1: actually related to one another. You might think, well, one

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Speaker 1: of these we're talking about natural language, and the other

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Speaker 1: one we're talking about logic gates. How do those end

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Speaker 1: up being related? Well, it's because machine code is based

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Speaker 1: upon the binary system zeros and ones and logics are

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Speaker 1: as well. And it turns out that the way we've

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Speaker 1: built computers is based upon this binary system, and that's

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Speaker 1: why we have machine code. It's this two humans. It's

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Speaker 1: a it's a complex way of trying to get a

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Speaker 1: machine to do a relatively simple task, or at least

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Speaker 1: one that seems simple to us. And unfortunately, there is

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Speaker 1: not an easy way to translate natural human language into

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Speaker 1: machine code in order to make a machine understand natural

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Speaker 1: language in a on a fundamental level, like on a

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Speaker 1: mechanical level, we would have to completely change the foundation

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Speaker 1: of computing. Yeah, so that's why it's a big deal. Uh.

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Speaker 1: You know. Instead, what we do is we end up

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Speaker 1: building programs that can understand on on a superficial level

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Speaker 1: what natural language is and translated into machine code so

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Speaker 1: that a computer can respond the proper way. It's not

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Speaker 1: true understanding, because again, a computer is just running processes.

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Speaker 1: It's just running, uh, series of calculations using these zeros

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Speaker 1: and ones and logic gates are the very foundation of that.

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Speaker 1: It's the foundation of circuit treats, the foundation of electronics,

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Speaker 1: and the foundation of computers. But it kind of goes

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Speaker 1: back a long way back, in fact, before there were

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Speaker 1: electronic computers. Oh yeah, I mean, because you know, I

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Speaker 1: I think of it as, uh, well, we actually have

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Speaker 1: an interesting article about it, um about something that has

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Speaker 1: come up with a couple of centuries ago by a

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Speaker 1: guy named George. Yeah you know. Oh yes, because logic

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Speaker 1: gates operate using Boolean logic, we have then there is

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Speaker 1: an article on how Boolean logic works, on how stuff

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Speaker 1: works dot com, I recommend actually, which is basically about

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Speaker 1: logic gates, which is kind of funny. I had no

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Speaker 1: idea until I started doing research on it um because

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Speaker 1: we also have a an article about how electronic gates

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Speaker 1: work on the the the site. But there's they're sort

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Speaker 1: of hand in hand. It's better probably to go back

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Speaker 1: through the bully and logic article first and then go

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Speaker 1: to the other um. But yeah, I mean, he basically

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Speaker 1: figured out how to use uh, you know, I guess

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Speaker 1: it's sort of the marriage of language and mathematical operation

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Speaker 1: in some ways, wouldn't you say? Yeah? And I also

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Speaker 1: tend to to relate it back to symbolic logic, which

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Speaker 1: is another way of marrying mathematics with language. Now, if

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Speaker 1: you're not familiar, symbolic logic is a concept where you

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Speaker 1: reduce statements to sort of almost like an equation, and

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Speaker 1: using the equation form, you evaluate that statement to determine

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Speaker 1: whether or not the statement or the combination of statements

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Speaker 1: is true or faulse um. And you know, you have

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Speaker 1: to make some certain assumptions in order to do that,

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Speaker 1: but you can build more and more complex equations using

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Speaker 1: all these series of statements to determine if the ultimate

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Speaker 1: conclusion is true or false, and by true or faulse,

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Speaker 1: we're really talking about whether the argument holds water or not.

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Speaker 1: So you can actually do this. You could take a

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Speaker 1: debate and you could take one person's side of the debate,

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Speaker 1: reduce it to this sort of mathematical equation, and then

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Speaker 1: determine whether or not the ultimate outcome of that of

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Speaker 1: that person's side of the debate makes sense from a

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Speaker 1: logical standpoint. Yeah. Now again we're talking logic here. We're

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Speaker 1: not talking about, uh, you know, trying to get someone

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Speaker 1: to agree to something based upon its emotional weight, but

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Speaker 1: simply does this argument makes sense? Does it follow the

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Speaker 1: rules of logic? Yeah? And a lot of these UM

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Speaker 1: when we talk about the logic gates UM, they're actually

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Speaker 1: devices inside electronics that use these logical operators, these rules,

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Speaker 1: these rules within the machine. Basically, they're passing instructions based

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Speaker 1: on the type of circuit they are and according I

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Speaker 1: actually look this up in Access Science, which is UM

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Speaker 1: a really awesome database for for technical things like this. UM. Basically,

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Speaker 1: the Access Science said that if you're creating a gate

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Speaker 1: circuit UM, they could be made up of transistors, diodes,

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Speaker 1: or resistors, in some combination. Now most today are are

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Speaker 1: generally transistors only, but they could be made up a

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Speaker 1: variety of components um and they're they're basically, you know,

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Speaker 1: you hook these up, and you can hook them up

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Speaker 1: in a variety of different ways depending on the type

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Speaker 1: of device and what you're trying to get it to do.

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Speaker 1: Um it. We'll get into that later, but basically, these

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Speaker 1: circuits are um a series of components that are wired

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Speaker 1: together to perform a logical operation within a device. So

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Speaker 1: let's start off from the very very very basic steps.

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Speaker 1: So it all begins with bits, zeros, and ones. Now

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Speaker 1: this these aren't just numbers zero and one does not

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Speaker 1: that doesn't that to us, That doesn't really mean anything

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Speaker 1: other than the fact that we can do mathematical processes

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Speaker 1: using them. As as as values zero and one um

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Speaker 1: they actually translate into other concepts. So a zero in

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Speaker 1: an electronics system would be a low voltage meaning zero volts,

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Speaker 1: and a one is high voltage, meaning five volts. So

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Speaker 1: a one means you've got electrons running through there at

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Speaker 1: five vaults. Zero means there are no electrons running through

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Speaker 1: zero vaults. But a zero also would mean a false statement.

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Speaker 1: One means a true statement. Zero could also be thought

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Speaker 1: of as being on in the off position. One is

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Speaker 1: in the on position. So let's we have to do.

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Speaker 1: You know, zero and one is kind of shorthand of saying.

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Speaker 1: So if we're talking about zeros, we're talking about false,

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Speaker 1: and we're talking about once, we're talking about true. For

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Speaker 1: time about zero's we're talking about low voltage. If we're

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Speaker 1: talking about one, we're talking about high voltage. This is

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Speaker 1: how we translate ideas conceptually into a real device, a

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Speaker 1: physical device that does something one there we go true.

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Speaker 1: So now a logic gate will process a signal and

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Speaker 1: what it does to that signal, like it has an

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Speaker 1: input and an output, what it does to that signal

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Speaker 1: when it comes in through the input is based upon

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Speaker 1: two things. The nature of the logic gate, because there

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Speaker 1: are several different basic types of logic gates, and the

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Speaker 1: whether or not the input was true or false, so

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Speaker 1: whether or not it was a one or a zero.

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Speaker 1: Those two elements will determine what the output of that

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Speaker 1: specific logic gate is. And the simplest logic gate is

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Speaker 1: a not git that's also known as an inverter. Yes,

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Speaker 1: Now inverters what they do is, they will take an

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Speaker 1: input and switch it to the opposite output. So, in

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Speaker 1: other words, if a zero is fed into a not gate,

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Speaker 1: it will produce a one. So false statement comes into

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Speaker 1: a not gate, it flips it to a true statement

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Speaker 1: coming out right, all right, so or against low voltage

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Speaker 1: to high voltage, yes, vice versa. So whatever the signal

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Speaker 1: coming into the the not gate is, the opposite goes out.

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Speaker 1: Now it can only have one input, which makes it

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Speaker 1: unique among the gates. The other gates have two or

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Speaker 1: more inputs, and they combine the two in order to

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Speaker 1: produce a result. Alright, So then the next one would

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Speaker 1: be an and gate. Now and gates will produce a

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Speaker 1: true result only if both inputs coming into the gate

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Speaker 1: are also true. I think of that like the programming

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Speaker 1: statement if then if both are true, then it will

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Speaker 1: return true results. So that means that let's say imagine

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Speaker 1: that you have this. You can actually imagine that this

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Speaker 1: is a gate and there are two roads leading into

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Speaker 1: the gate, and you have two cars going up to

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Speaker 1: the gate. If both cars are are true, then you've

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Speaker 1: got a true result coming out. Otherwise you have a

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Speaker 1: false result coming out. Actually, it would be and if

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Speaker 1: and only if yes. So, in other words, if you

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Speaker 1: have to If you have these two uh inputs coming

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Speaker 1: into the and gate and both are a one, so

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Speaker 1: both are true, both are high voltage, you get a

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Speaker 1: one as a result. Any other combination you get a

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Speaker 1: zero as a result a false statement or low voltage.

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Speaker 1: Zero and one will equal zero. In this case, zero

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Speaker 1: zero will be zero, zero one will be zero, one

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Speaker 1: zero will be zero because you have to think of

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Speaker 1: all three instances that way. Even though you might say, wait,

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Speaker 1: zero one and one zero, isn't that the same thing? No,

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Speaker 1: Because you're talking about two different inputs coming into a gate,

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Speaker 1: and those two inputs are coming from two different sources.

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Speaker 1: Sometimes yeah, sometimes they come from the same source, but

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Speaker 1: usually they come from two different sources. And that means

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Speaker 1: that because they're coming from two different sources, you have

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Speaker 1: two different configurations. You have one where one is true

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Speaker 1: and one is faults, and another one where one is

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Speaker 1: faults and the other is true. Sounds kind of complicated,

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Speaker 1: it's actually pretty simple. And again, if this starts to

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Speaker 1: sound confusing, check out these articles that we have on

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Speaker 1: our site because they will help illustrate these concepts. So,

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Speaker 1: besides the end gate, you have the nand gate or

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Speaker 1: not and now and not and will produce a true

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Speaker 1: result in every case except where both inputs or more

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Speaker 1: are true, because you can have more than two inputs

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Speaker 1: in an end or a nand gate. So in other words,

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Speaker 1: if you have two zeros, a zero, one, or a

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Speaker 1: one zero, you're gonna get a one out of a

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Speaker 1: nand gate. If it's a one and one, it's going

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Speaker 1: to come out as a zero in a nand gate, right,

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Speaker 1: Then you've got the or gate, and or gate will

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Speaker 1: produce a true result if at least one of the

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Speaker 1: inputs is true, so zero, one, one, zero, and one

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Speaker 1: one will all produce a one. Only zero zero produces

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Speaker 1: a zero or a false statement. Then you've got the

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Speaker 1: Nora gate, which is not or It will produce a

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Speaker 1: true result if both inputs are false, so zero zero

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Speaker 1: will produce a one zero, one one zero and one

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Speaker 1: one will produce a zero. Then you have now all

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Speaker 1: of those gates, the the and nand or and nor

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Speaker 1: gates can receive multiple inputs. And in order to really

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Speaker 1: kind of sort this out, I know it sounds confusing,

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Speaker 1: you can actually build a truth table. A truth table

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Speaker 1: is essentially just a it's like it's almost like a spreadsheet,

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Speaker 1: and it shows you what each scenario, what the outcome

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Speaker 1: would be for that particular scenario for that particular gate.

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Speaker 1: So like if A equal zero and be equal zero,

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Speaker 1: results C will equal whatever I should say result Q

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Speaker 1: because that's typically how they label it in uh in diagrams. Yeah,

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Speaker 1: they usually use a que to differentiate, so there's no

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Speaker 1: confusion that it's zero. They they you use a que

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Speaker 1: so that you get the ideas. Oh yeah, that's the output.

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Speaker 1: Um yeah, I was just gonna say that truth table

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Speaker 1: kind of sounds like a medieval torture device. Him on

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Speaker 1: the truth table, nobody resists the machine. I really don't

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Speaker 1: know what that would do to you. Um Now I

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Speaker 1: just quote Princess Bride, but of this, I was gonna

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Speaker 1: say that there's an extra bonus movie quote. Remember this

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Speaker 1: is for posterity, so please be honest. There are two

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Speaker 1: more gates. Two more gates. Yes, there's X or the

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Speaker 1: exclusive or gate, which produces a true result if the

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Speaker 1: two inputs are different. So if a zero, zero or

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Speaker 1: one one comes into an ex or gate, you're gonna

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Speaker 1: get a zero, right if you get a if it's

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Speaker 1: one zero or zero, one going into an ex orgate

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Speaker 1: get a one. Uh. Now, because of the nature of

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Speaker 1: this gate, it can only accept two inputs. You cannot

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Speaker 1: you cannot have multiple inputs beyond two in an x

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Speaker 1: or gate because it has to be specifically geared that way. Right,

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Speaker 1: because because it has to be if it if it's if,

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Speaker 1: if they have to be different. Uh, then there are

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Speaker 1: only two choices, right, there's a zero, there's a one.

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Speaker 1: If you have three inputs going into something and they

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Speaker 1: have to be different and there's only two choices, there's

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Speaker 1: no way two of those inputs have to be the same.

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Speaker 1: Bye bye again following logic. So therefore, and an ex

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Speaker 1: or gate, only two inputs can go into that gate.

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Speaker 1: Then you have the x nore gate and it produces

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Speaker 1: a true result if both inputs are the same. So

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Speaker 1: if a zero zero or a one one goes into

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Speaker 1: an exnore gate, you get a one. Otherwise you get

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Speaker 1: a zero. Same thing as the ex or gate in

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Speaker 1: that you can only have two inputs going into that gate. Now,

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Speaker 1: using these gates that we have just described here, if

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Speaker 1: you build you can actually build up a circuit using

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Speaker 1: those as their basic building blocks. In fact, you can

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Speaker 1: go to a hobby store and buy chips that have

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Speaker 1: logic gates built onto them. Yes, and we were talking

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Speaker 1: about the the RDU know a few weeks ago, And

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Speaker 1: these are the kinds of projects now if you can

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Speaker 1: get a basic grip on this, these are the kinds

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Speaker 1: of things that you can add to your projects if

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Speaker 1: you're doing um hobbies yourself and want to do this. Now,

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Speaker 1: you know, once you get a basic understanding of this,

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Speaker 1: you can make much more complex projects. Yeah, so, uh

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Speaker 1: you know, we you can consider building a circuit using

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Speaker 1: this as as using combinational logic. You're combining various gates

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Speaker 1: together in order to get a different results. So you

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Speaker 1: might have three inputs going into a system, and then

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Speaker 1: you you align various gates in a very in a

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Speaker 1: particular sequence in order to get a different result, and

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Speaker 1: it all will obey the laws of the truth tables. Now,

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Speaker 1: these these circuits can get pretty lunkey and pretty complex,

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Speaker 1: which is why we've sort of abandoned the uh you know,

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Speaker 1: it works great as a concept. In reality, we've virtualized

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Speaker 1: a lot of this since then because it just otherwise

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Speaker 1: it would just be a massive piece of hardware in

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Speaker 1: order to build a really really complex circuit um. But

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Speaker 1: you you can actually lay these out in various configurations

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Speaker 1: to get different results. So it might you might have

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Speaker 1: uh two inputs going into and and UH gate and

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Speaker 1: another input going into a not gate, and then those

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Speaker 1: the results of those um of those particular functions will

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Speaker 1: go into a third gate and then now that way

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Speaker 1: you have something coming out like maybe the maybe those

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Speaker 1: are both going into an ex or gate, and then

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Speaker 1: whatever the result is is what you're looking for. Uh. These,

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Speaker 1: like I said, get pretty clunky pretty fast. The interesting

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Speaker 1: thing is you can actually replace the function of some

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Speaker 1: of these gates using other gates. You just have to

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Speaker 1: put them in the right configu duration to do so.

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Speaker 1: So you can think of some of these gates is

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Speaker 1: almost being like shorthand like this gate does this one

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Speaker 1: function and so therefore uh it does it um. You know,

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Speaker 1: that's all it does. You just put that in this place.

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Speaker 1: But sometimes you might be working with a system where

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Speaker 1: you don't want to have lots of different types of gates.

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Speaker 1: You want to use maybe one or two types of

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Speaker 1: gates and you don't want to have to deal with

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Speaker 1: all the others. Well you can do that. You just

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Speaker 1: have to build the gates in the proper sequence in

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Speaker 1: order to get the result you want, UH for it

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Speaker 1: to to copy the function of one of the other gates.

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Speaker 1: And there's various ways of doing this. Now, it does

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Speaker 1: mean that you're going to use more gates overall usually

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Speaker 1: than you would if you were using the the different types,

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Speaker 1: but you would all be using the same type of gates.

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Speaker 1: So you're you've reduced it to a single type of gate,

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Speaker 1: but you you're using more of that particular gate than

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Speaker 1: you would if you were using multiple types of gates.

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Speaker 1: Sounds a little complicated, but it does. It does mean

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Speaker 1: that when you're sketching it out, it really cuts down

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Speaker 1: on the sort of gates that you have to design

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Speaker 1: when you're when you're at least conceptually building your circuitry. Now,

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Speaker 1: go ahead, and I was just gonna say that these

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Speaker 1: these gates can be run in parallel or in a series,

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Speaker 1: and um it actually kind of reminds me in a

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Speaker 1: way of a very complex UH railway, because I mean,

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Speaker 1: you're basically using these switches to control the flow of

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Speaker 1: information in your electronic device. Um So as a you know,

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Speaker 1: as someone would watch the board and make sure that

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Speaker 1: the trains don't collide. Um. You're also sort of you know,

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Speaker 1: you can actually control the way information flows through the

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Speaker 1: device using these switches, and you can place them in

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Speaker 1: ways that make the most sense to to what you're

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Speaker 1: trying to carry out, which is essentially what you just said.

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Speaker 1: But um, it helps me think about this conceptually, to

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Speaker 1: put it in and out analogy from that to something

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Speaker 1: that I can think about, like trains, because trains are

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Speaker 1: nice and and if you wanna, you know, if you

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Speaker 1: really want to get into this, each of these gates

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Speaker 1: has a particular um graphical representation of you know, what

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Speaker 1: it does. So it's I'm not bothering describing it on

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Speaker 1: the podcast because this is an audio podcast. It would

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Speaker 1: be kind of it would be kind of pointless to

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Speaker 1: do it. And the shapes, the shapes aren't you know,

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Speaker 1: like a circle or a triangle or a square something

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Speaker 1: that is uh easy to describe, a lot of these

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Speaker 1: shapes are modifications of those types of things. So you

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Speaker 1: might say a trianglar looking thing, but you're really not

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Speaker 1: going to get it. It makes more sense to actually

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Speaker 1: go to a website that has them all laid out,

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Speaker 1: and then once you learn what the the sort of

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Speaker 1: graphic representation of a gate what it looks like. You

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Speaker 1: can start looking at um the combination of gates and say, oh,

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Speaker 1: well that's an and gate. So that means that since

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Speaker 1: I know that and gates always give a result, that is,

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Speaker 1: it will produce a true result only if both inputs

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Speaker 1: are true. I know what the output of this end

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Speaker 1: gate will be depending upon the inputs. So, because it's

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Speaker 1: always going to behave the same way, it's never going

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Speaker 1: to behave uh in a way opposite or different unless

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Speaker 1: you you know, well never, it will never do that.

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Speaker 1: It's only if you were using a nand gate that

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Speaker 1: it would be different than the way it normally is. UM.

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Speaker 1: So that way, since you know how each gate behaves

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Speaker 1: in any specific circumstance given time, you can decipher what

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Speaker 1: a fairly complex diagram will do. You just say, all right,

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Speaker 1: I know that this gate always behaves this way. Therefore,

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Speaker 1: this is what would happen given this particular series of inputs.

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Speaker 1: You can actually build out a truth table for a

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Speaker 1: complex circuit that way, and you will ultimately know what

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Speaker 1: the circuit will produce given any particular set of circumstances. Now,

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Speaker 1: the more complex a circuit gets the wider that truth

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Speaker 1: table is gonna be, and the more you're gonna have

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Speaker 1: to really check to make sure you're following the logical

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Speaker 1: rules so that the results are are accurate, um other

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Speaker 1: and we call this, we actually call this programming a circuit.

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Speaker 1: Even though you might think of programming is something you

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Speaker 1: do sitting down typing on a keyboard. This and this

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Speaker 1: involves actual physically hooking up wires to logic gates in

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Speaker 1: whatever sequence or series you need. Uh, we still call

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Speaker 1: that programming. Yeah, an engineer might graft this out using

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Speaker 1: these symbols on a piece of paper to get an

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Speaker 1: idea of how it works. But logic gates can be

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Speaker 1: very very small. I mean, we're we we've talked about

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Speaker 1: the manufacture of transistors before. I mean, you can have

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Speaker 1: millions of transistors and a very small piece of silicon

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Speaker 1: and the logic gates I mean, using the metal oxide

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Speaker 1: semiconductor UH type, which is apparently predominant according to Access

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Speaker 1: Science and manufacturing today, you can have many, many of

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Speaker 1: these devices. So it helps I mean, I think it

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Speaker 1: would help me if I were trying to figure out

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Speaker 1: exactly how I wanted to lay out this device to

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Speaker 1: have it you know, drafted out with these symbols and

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Speaker 1: get an idea of how it's it's working. I'm sure

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Speaker 1: a lot of them use computers. Actually have a program

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Speaker 1: that I use for information architecture that has a template

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Speaker 1: with all these symbols on there, and then you can,

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Speaker 1: you know, put it up on the screen and get

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Speaker 1: an idea of how it works. But that's far larger

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Speaker 1: than the actual devices because the manufacturing process can make

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Speaker 1: them very very tiny, right, And as we've said in

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Speaker 1: other podcasts, this is part of why miniaturization has some

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Speaker 1: uh some challenges, uh that go along with it. I mean,

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Speaker 1: there are a lot of different challenges, but one of

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Speaker 1: the challenges is that by getting these gates to be

396
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Speaker 1: smaller and smaller, each each element on a transistor is

397
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Speaker 1: decreasing in size. Remember, if we're following Moore's law, then

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Speaker 1: ideally you're going to be able to fit twice as

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Speaker 1: many discrete elements on a chip within twenty four months,

400
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Speaker 1: or at least the the number of discrete elements on

401
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Speaker 1: a chip will be twice as many as it would

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Speaker 1: have been twenty four months before, so two years before

403
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Speaker 1: um with that, with those elements decreasing in size. At

404
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Speaker 1: that pace, you start to run up against some pretty

405
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Speaker 1: challenging issues and we've talked about it several times on

406
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Speaker 1: the podcast before, Like electron tunneling. So if you have

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Speaker 1: a gate that determines how what the result it needs

408
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Speaker 1: to be from any given inputs, um, if you have

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Speaker 1: an electron that can tunnel past that gate, then it

410
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Speaker 1: overrides the function of that gate, which means it will

411
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Speaker 1: start creating errors in your calculations. You know, you think

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Speaker 1: about these these gates being so small that electron can

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Speaker 1: tunnel through them. And by the way, electrons don't really

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Speaker 1: tunnel through them, they just appear on the other side

415
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Speaker 1: of the gate. Actually, if you think of it this way,

416
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Speaker 1: think of as an electron as just being a uh.

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Speaker 1: It's you can predict that electron will appear somewhere within

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Speaker 1: a given area, all right, but you don't know the

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Speaker 1: specific location of that electron. So within a given area,

420
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Speaker 1: think of it like a sphere. You've got the sphere,

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Speaker 1: and somewhere inside that sphere is this electron. Right as

422
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Speaker 1: that sphere approaches the gate, then part of that sphere

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Speaker 1: is going to go over the gate. Uh and meaning

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Speaker 1: that the electron could in theory somehow exists on the

425
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Speaker 1: other side of that gate without passing through it. That

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Speaker 1: means that because there is a chance that the electron

427
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Speaker 1: could somehow exist on the other side of that gate

428
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Speaker 1: without passing through it, sometimes it does. Because there's a chance,

429
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Speaker 1: yes and anything that if there is a chance for

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Speaker 1: something to happen eventually, sooner or later, it happens. So

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Speaker 1: that's the definition of chance. If there's no chance that

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Speaker 1: it won't happen. So right, exactly, there's Schrodinger shake fist.

433
00:24:38,200 --> 00:24:41,200
Speaker 1: Actually it's more like Heisenberg's and certainty principle. But anyway, um,

434
00:24:41,600 --> 00:24:44,040
Speaker 1: but I was thinking you just weren't sure about it,

435
00:24:44,119 --> 00:24:46,679
Speaker 1: right exactly, there you go. So anyway, the electron, because

436
00:24:46,680 --> 00:24:48,880
Speaker 1: it can sometimes be on the other side of that gates.

437
00:24:48,920 --> 00:24:50,760
Speaker 1: Sometimes it is on the other side of that gate.

438
00:24:50,800 --> 00:24:52,440
Speaker 1: That's one of the challenges we have when we get

439
00:24:52,480 --> 00:24:55,040
Speaker 1: these these gates at these tiny, tiny size. You know

440
00:24:55,119 --> 00:24:58,440
Speaker 1: that the thickness is not thick enough to prevent electron

441
00:24:58,480 --> 00:25:02,720
Speaker 1: tunneling unless start switching to other materials which are more

442
00:25:02,720 --> 00:25:05,840
Speaker 1: resistant to electron tunneling, which is so complex. I still

443
00:25:05,880 --> 00:25:07,320
Speaker 1: have not gotten a good grip on it. So I

444
00:25:07,320 --> 00:25:10,000
Speaker 1: can't really explain why that is. I just know that

445
00:25:10,160 --> 00:25:14,600
Speaker 1: really smart people at Intel have figured it out. Anyway. Uh,

446
00:25:14,640 --> 00:25:16,439
Speaker 1: that's one of the reasons why we talk about this

447
00:25:16,520 --> 00:25:20,920
Speaker 1: miniaturization process being a challenge to keeping Moore's Law going

448
00:25:21,119 --> 00:25:23,239
Speaker 1: because remember More's Law is not truly a law, it's

449
00:25:23,280 --> 00:25:26,760
Speaker 1: an observation, and companies are struggling to make sure that

450
00:25:26,800 --> 00:25:30,159
Speaker 1: they meet the expectation laid out in that observation and

451
00:25:30,320 --> 00:25:34,200
Speaker 1: self fulfilling prophecy. Yes, yeah, because once More's Law ends,

452
00:25:34,280 --> 00:25:36,359
Speaker 1: then you know, the chaos will rain and robots will

453
00:25:36,359 --> 00:25:39,400
Speaker 1: take over the earth and etcetera, and zombies and brains anyway.

454
00:25:39,480 --> 00:25:43,760
Speaker 1: So um again, because logic gates are the very basis

455
00:25:43,880 --> 00:25:47,440
Speaker 1: of these calculations. If the electron ignores the logic gate,

456
00:25:48,040 --> 00:25:52,200
Speaker 1: computing stops working. So that's why we talk about electron tunneling,

457
00:25:52,280 --> 00:25:56,680
Speaker 1: quantum mechanics, and quantum engineering in relation to microprocessors, because

458
00:25:56,680 --> 00:25:59,720
Speaker 1: they're built on this foundation of logic gates and they

459
00:25:59,720 --> 00:26:03,359
Speaker 1: are basic. Microprocessor is going to be so complex that

460
00:26:03,480 --> 00:26:06,160
Speaker 1: to sketch it out and a logic gate formation would

461
00:26:06,200 --> 00:26:11,000
Speaker 1: be pretty intense. But the nice thing is you can

462
00:26:11,080 --> 00:26:13,520
Speaker 1: learn the basics of this pretty simply, like I said,

463
00:26:13,600 --> 00:26:15,760
Speaker 1: you go to a couple of websites and look at

464
00:26:15,920 --> 00:26:18,960
Speaker 1: how the logic gates are are displayed in a in

465
00:26:19,040 --> 00:26:21,480
Speaker 1: a sketch. And you can even go out to a

466
00:26:21,520 --> 00:26:23,920
Speaker 1: hobby store and buy chips that have logic gates on

467
00:26:23,960 --> 00:26:26,359
Speaker 1: them and learn how to hook them up yourself and

468
00:26:26,480 --> 00:26:30,719
Speaker 1: see it in action. It's pretty cool. It's a it's

469
00:26:30,760 --> 00:26:33,040
Speaker 1: a neat project. There's a neat way to really start

470
00:26:33,080 --> 00:26:37,479
Speaker 1: getting your feet wet in designing electronics, and there are

471
00:26:37,480 --> 00:26:40,320
Speaker 1: plenty of different tutorials out there to explain how to

472
00:26:40,400 --> 00:26:42,959
Speaker 1: do that and what why you would do that, Like

473
00:26:43,000 --> 00:26:44,560
Speaker 1: you know, yeah, I've hooked up a lot of wires

474
00:26:44,640 --> 00:26:46,800
Speaker 1: to this thing and it's doing this thing, but I

475
00:26:46,800 --> 00:26:48,840
Speaker 1: have no idea why it's doing it or or what's

476
00:26:48,840 --> 00:26:52,399
Speaker 1: the purpose. This is just the foundation, the building blocks

477
00:26:53,119 --> 00:26:56,119
Speaker 1: um and then hopefully maybe in the future podcasts we

478
00:26:56,160 --> 00:27:00,680
Speaker 1: can go into stuff like sequential logic, as we're talking

479
00:27:00,680 --> 00:27:05,080
Speaker 1: about combinational logic right now. Sequential logic depends on other

480
00:27:05,200 --> 00:27:10,000
Speaker 1: concepts like state, like an information state. You know, we

481
00:27:10,080 --> 00:27:13,800
Speaker 1: say that an information has state if it carries over

482
00:27:13,880 --> 00:27:16,919
Speaker 1: information from previous calculations. If I were to give you

483
00:27:16,960 --> 00:27:20,000
Speaker 1: a simple calculation. If I were to say, all right,

484
00:27:20,440 --> 00:27:23,720
Speaker 1: add one variable to another variable and you get a

485
00:27:24,080 --> 00:27:27,000
Speaker 1: sum of those two variables. All right, Well, there's no

486
00:27:27,119 --> 00:27:30,399
Speaker 1: state in that in that function I just gave you,

487
00:27:30,440 --> 00:27:33,159
Speaker 1: because you could take any two variables you wanted and

488
00:27:33,200 --> 00:27:36,560
Speaker 1: you're going to get a sum. But there's that that

489
00:27:36,680 --> 00:27:39,760
Speaker 1: sum has no information on it based upon the previous

490
00:27:39,920 --> 00:27:43,400
Speaker 1: two numbers you added to it, right, Because you might say,

491
00:27:43,400 --> 00:27:44,960
Speaker 1: all right, for this one, I'm going to add three

492
00:27:44,960 --> 00:27:46,640
Speaker 1: and four I got seven, And this one i'm gonna

493
00:27:46,680 --> 00:27:50,240
Speaker 1: add five and nine I got fourteen, and they have

494
00:27:50,320 --> 00:27:54,359
Speaker 1: no bearing on each other. Information that has a state

495
00:27:54,520 --> 00:27:58,480
Speaker 1: has bearing upon previous calculations, and that's very important for computing.

496
00:27:58,520 --> 00:28:00,720
Speaker 1: Without it, computers would own we be able to do

497
00:28:01,160 --> 00:28:03,720
Speaker 1: really one function and then the next function will have

498
00:28:03,800 --> 00:28:06,359
Speaker 1: nothing to do with the next uh with the with

499
00:28:06,400 --> 00:28:08,200
Speaker 1: the one you did before. So it would be impossible

500
00:28:08,200 --> 00:28:10,840
Speaker 1: to really build a program. You would have to have

501
00:28:10,880 --> 00:28:13,720
Speaker 1: something that has some form of state so it can

502
00:28:13,800 --> 00:28:17,960
Speaker 1: build upon what has come previously. That really goes into

503
00:28:17,960 --> 00:28:20,919
Speaker 1: sequential logic. It's its own thing. We will tackle that

504
00:28:21,000 --> 00:28:23,640
Speaker 1: in a different podcast, because that's gonna have some more

505
00:28:23,840 --> 00:28:27,080
Speaker 1: kind of complex conversations to kind of get into you know,

506
00:28:27,160 --> 00:28:29,800
Speaker 1: what sequential logic is, what it means, and how do

507
00:28:29,880 --> 00:28:33,560
Speaker 1: we achieve it. But but really you can't get there

508
00:28:34,040 --> 00:28:38,280
Speaker 1: without first looking at the logic gates issue. So I

509
00:28:38,360 --> 00:28:41,520
Speaker 1: want to thank our listeners who have requested logic Gates

510
00:28:41,560 --> 00:28:44,400
Speaker 1: because it is a really important topic. It's a really

511
00:28:44,440 --> 00:28:46,880
Speaker 1: fun topic really if you like puzzles. I I was

512
00:28:46,920 --> 00:28:49,800
Speaker 1: telling Chris before this that symbolic logic is one of

513
00:28:49,840 --> 00:28:52,400
Speaker 1: my was one of my favorite classes in college. I

514
00:28:52,760 --> 00:28:56,600
Speaker 1: was in English literature major with a focus on shakespearean

515
00:28:57,000 --> 00:29:02,520
Speaker 1: uh drama, but somehow symbolic logic became one of my

516
00:29:02,600 --> 00:29:06,200
Speaker 1: favorite classes because it just made sense to me. And

517
00:29:06,280 --> 00:29:09,760
Speaker 1: I love these sort of puzzles where you just you

518
00:29:09,800 --> 00:29:12,240
Speaker 1: look at this big picture and it looks really complex

519
00:29:12,360 --> 00:29:15,560
Speaker 1: and really overwhelming, but if you just know the rules,

520
00:29:16,080 --> 00:29:19,719
Speaker 1: with enough time and attention, you can figure out how

521
00:29:19,760 --> 00:29:23,720
Speaker 1: it all works. And that's amazing. I don't know, I'm

522
00:29:24,040 --> 00:29:26,960
Speaker 1: pretty illogical. I'm not sure. Well I I when I'm

523
00:29:27,000 --> 00:29:29,440
Speaker 1: saying you, I really mean me, I don't mean you

524
00:29:30,360 --> 00:29:35,560
Speaker 1: you Okay. So anyway, that covers our episode on logic gates.

525
00:29:35,680 --> 00:29:38,680
Speaker 1: If you have any requests for particular episodes, whether they

526
00:29:38,720 --> 00:29:41,880
Speaker 1: be really technical or not so technical, just let us know.

527
00:29:42,040 --> 00:29:44,600
Speaker 1: You can say as an email that address is tech

528
00:29:44,640 --> 00:29:47,840
Speaker 1: stuff at how stuff Works dot com, or you can

529
00:29:47,960 --> 00:29:51,000
Speaker 1: send us a request via Twitter or Facebook or handle

530
00:29:51,040 --> 00:29:53,560
Speaker 1: at both of those is tech Stuff h SW. And

531
00:29:53,600 --> 00:29:57,080
Speaker 1: we should also point out recently we launched a brand

532
00:29:57,080 --> 00:30:00,360
Speaker 1: new iPad app, So if you are an iPad owner

533
00:30:00,480 --> 00:30:02,880
Speaker 1: like the fellow sitting across the table for me, and

534
00:30:02,960 --> 00:30:05,880
Speaker 1: you want to have some fun with a new app

535
00:30:05,960 --> 00:30:08,800
Speaker 1: that has a lot of our great content all bundled

536
00:30:08,800 --> 00:30:12,800
Speaker 1: in their specifically designed for the layout on the iPad,

537
00:30:13,160 --> 00:30:15,760
Speaker 1: check that out because it's been, uh, it's been really

538
00:30:15,800 --> 00:30:17,880
Speaker 1: impressing everyone around the office for a couple of weeks,

539
00:30:17,920 --> 00:30:19,680
Speaker 1: and now that it's out there in the wild, we're

540
00:30:19,720 --> 00:30:23,240
Speaker 1: really excited to see what people think. And Chris and

541
00:30:23,280 --> 00:30:26,040
Speaker 1: I will talk to you again, hopefully with a little

542
00:30:26,040 --> 00:30:31,120
Speaker 1: bit of logic really soon. Be sure to check out

543
00:30:31,160 --> 00:30:34,320
Speaker 1: our new video podcast, Stuff from the Future. Join How

544
00:30:34,400 --> 00:30:37,600
Speaker 1: Stuffwork staff as we explore the most promising and perplexing

545
00:30:37,680 --> 00:30:42,360
Speaker 1: possibilities of tomorrow. The House Stuff Works iPhone app has arrived.

546
00:30:42,480 --> 00:30:49,640
Speaker 1: Download it today on iTunes. Brought to you by the

547
00:30:49,640 --> 00:30:53,040
Speaker 1: reinvented two thousand twelve Camray. It's ready, Are you