Speaker 1: Welcome to Tech Stuff, a production from iHeartRadio. Hey thereon
Speaker 1: Welcome to Tech Stuff. I'm your host, Jonathan Strickland. I'm
Speaker 1: an executive producer with iHeartRadio. And how the tech are you?
Speaker 1: So I threatened? Sorry, I mean I mentioned last week
Speaker 1: that I planned to do an episode about logic gates,
Speaker 1: which light at the heart of computer processing. So today
Speaker 1: we're going to do a quick overview of logic gates
Speaker 1: and what they do. And originally I was going to
Speaker 1: run reruns this week because I'm actually on vacation as
Speaker 1: you listen to this, but I had a little extra
Speaker 1: pizazz in my step that I'll talk about in a second.
Speaker 1: But yeah, let's talk about logic gates and what they do.
Speaker 1: And first up, you should know that logic gates are
Speaker 1: based off of Boolean algebra. This branch of math was
Speaker 1: invented by the guy that it was named after, George Algebra.
Speaker 1: Just kidding. His name was George Bull. Bull was born
Speaker 1: in England in eighteen fifteen, as so many were. He
Speaker 1: died forty nine years later in Ireland. And I can
Speaker 1: understand why. I guess this is where I should mention.
Speaker 1: I'm writing this episode while under the influence of advil
Speaker 1: PM because I grabbed the wrong tablets while trying to
Speaker 1: treat a headache. So that's going to be a factor
Speaker 1: for the rest of this episode, just like you know. Anyway,
Speaker 1: George Bull helped establish symbolic logic, which, by the way,
Speaker 1: I loved that subject in college. It was a math
Speaker 1: course that I excelled at. In fact, I would only
Speaker 1: show up to class on Thursdays and Fridays. We met
Speaker 1: every day of the week, but there was no attendance policy.
Speaker 1: So Thursday I would show up to find out which
Speaker 1: chapters that the professor had gone over, and then Friday
Speaker 1: I would show up because there was a quiz for
Speaker 1: that week's lessons. And symbolic logic made so much sense
Speaker 1: to me that I could just show up on Thursday
Speaker 1: to see which chapters that needed to read, show up
Speaker 1: Friday and do the work. And I aced that class.
Speaker 1: Now this is not to say that I'm a genius.
Speaker 1: I am not. Just for some reason or another, symbolic
Speaker 1: logic clicked with me in a way that a lot
Speaker 1: of subjects never did. Anyway, symbolic logic would become a
Speaker 1: fundamental foundation for digital circuits. Years later, my guess is
Speaker 1: he didn't know that was going to happen because computers
Speaker 1: weren't a thing yet. So what had happened was Bull
Speaker 1: mostly learned mathematics all on his own. He received some
Speaker 1: tutoring from his father, who was a tradesman, and he
Speaker 1: did go to a couple of schools, but no like
Speaker 1: secondary formal education. Mainly he was self taught, and he
Speaker 1: actually began teaching around various schools in his region when
Speaker 1: he was just sixteen years old, not only because he
Speaker 1: was brilliant, but also because it was necessary. His father's
Speaker 1: business had slowed down and his family needed the income.
Speaker 1: So the gig economy has been around for a while,
Speaker 1: I guess is what I'm saying. In the eighteen forties,
Speaker 1: Bull submitted papers to the Cambridge Mathematical Journal on subjects
Speaker 1: ranging from differential equations to calculus, you know, light reading.
Speaker 1: In eighteen forty seven, he published a work titled the
Speaker 1: Mathematical Analysis of Logic Being an Essay toward a Calculus
Speaker 1: of Deductive reasoning. This landed him a university teaching gig,
Speaker 1: even though he had never earned a college degree of
Speaker 1: his own. In eighteen forty five, he published a further
Speaker 1: treatment of his ideas titled an Investigation into the Laws
Speaker 1: of Thought on which are founded the mathematical theories of
Speaker 1: logic and probabilities Real Page Turner. In eighteen forty six
Speaker 1: he married Mary Everest, the daughter of Mount Everest. Okay, wait, no, sorry, no,
Speaker 1: she was the daughter of George Everest. It's just that
Speaker 1: Mount Everest is named after George Everest. That's actually true.
Speaker 1: I got a little confused there. Sorry, I'm blaming the ADVILPM.
Speaker 1: At this point, Boole used mathematical symbols to represent logical
Speaker 1: arguments and showed that by encoding an argument as a
Speaker 1: series of equations, one could check to see if the
Speaker 1: argument was sound or not, if it were true, or
Speaker 1: if it were false. So, for example, maybe you were
Speaker 1: saying something like all cats are mammals, Old Greg is
Speaker 1: a cat, therefore old Greg is a mammal. Well, you
Speaker 1: could actually represent those statements as equations, and then you
Speaker 1: could solve to show that the conclusion is contained within
Speaker 1: the premises. So if the premisses contained the conclusion and
Speaker 1: everything lines up, you would say it's logically sound. It
Speaker 1: is a true argument. However, if you said all cats
Speaker 1: are mammals. Old Greg likes to sip Bailey's out of
Speaker 1: a shoe. Therefore, Old Greg is a mammal. Well, that
Speaker 1: wouldn't fly because you haven't established that Old Greg is
Speaker 1: a cat or any other kind of mammal for that matter.
Speaker 1: He's Old Greg. So what does this have to do
Speaker 1: with computers. Well, Old Greg will have nothing to do
Speaker 1: with computers, probably because he lives at the bottom of
Speaker 1: a lake and his computer with short circuit immediately. But
Speaker 1: boolean logic would underpin the concept of logic gates, which
Speaker 1: in turn would allow a computer to process information in
Speaker 1: a meaningful way. And this brings us to the concept
Speaker 1: of actual logic gates. PCMag dot com defines logic gates
Speaker 1: as quote a collection of transistors and resistors that implement
Speaker 1: boolean logic operations in a digital circuit. Logic gates have
Speaker 1: one or two zero or one inputs, but only one
Speaker 1: zero or one output, as in the following examples, which
Speaker 1: they then list to continue the quote. Transistors make up gates,
Speaker 1: Gates makeup circuits, and circuits may up electronic systems. End quote.
Speaker 1: So a typical logic gate usually accepts two inputs and
Speaker 1: produces a single output, and that output is based both
Speaker 1: upon the nature of the inputs and the nature of
Speaker 1: the gate itself. I say typically, because of course there
Speaker 1: are exceptions, but for the purposes of simplicity, we're mainly
Speaker 1: focusing on the typical example of two inputs enter, one
Speaker 1: output leaves. So yeah, I am going thunderdome with these rules.
Speaker 1: The output that a logic gate produces, like I said,
Speaker 1: depends both upon the value of the inputs and the
Speaker 1: type of logic gait that we're talking about. So you
Speaker 1: can think of logic gates being kind of like a
Speaker 1: physical gate that leads into, say a courtyard, and this
Speaker 1: particular gate has a bouncer standing outside of it. The
Speaker 1: bouncer enforces the rules. So you come up to the gate,
Speaker 1: and if you meet certain criteria, the bouncer lets you through,
Speaker 1: and if you do not meet the criteria, the bouncer
Speaker 1: turns you away. This analogy isn't perfect, because really the
Speaker 1: logic gates allow a value to pass through no matter
Speaker 1: what it's just what value is that going to be?
Speaker 1: Will it be a zero or will it be a one.
Speaker 1: So the bouncers in circuits are electronic components, and the
Speaker 1: rules depend upon the type of gait. And we are
Speaker 1: talking physical structures here in a circuit. We're actually talking
Speaker 1: about transistors and resistors. So the way the gates work
Speaker 1: is dependent upon voltage. So each input can have one
Speaker 1: of two values. Either zero volts is applied to the input,
Speaker 1: which would then represent an input of zero, or five
Speaker 1: positive volts are inputed into that input and then that
Speaker 1: represents a one. The output produces a value of either
Speaker 1: zero volts, so a zero in logic, or five volts
Speaker 1: again meaning a one in logic. Now, if we just
Speaker 1: talking two inputs, you can have four possible combinations, right,
Speaker 1: So each input can have one of two states, either
Speaker 1: a zero or a one. And if we start to
Speaker 1: group these two inputs together, that gives us four potential combos.
Speaker 1: You could have both input A and input B B zero,
Speaker 1: so that's one value. Or you could have both of
Speaker 1: them be one that's a second value. Or you could
Speaker 1: have input A B zero, input B is one that's
Speaker 1: a third value. Or you could have input A B
Speaker 1: one and input B is zero that's your fourth value.
Speaker 1: So four possible combinations zero, zero, zero, one, one zero
Speaker 1: or one one. Now, those are the basics when we
Speaker 1: come back. We're gonna talk about the different kinds of
Speaker 1: logic gates, and we'll build from the most basic to
Speaker 1: the more complicated. But first let's take this quick break
Speaker 1: to thank our sponsor. We're back, So now we're going
Speaker 1: to talk about logic gates, and the first one up
Speaker 1: is the and logic gate. The and logic gate will
Speaker 1: produce a one result as the output only if both
Speaker 1: inputs are also one. So if input A is one,
Speaker 1: an input B is one, then the output is also one.
Speaker 1: Any other combination, whether it's zero, zero, zero, one, or
Speaker 1: one zero, will have an output of zero. So an
Speaker 1: and gate will produce a one if both inputs are
Speaker 1: also one. Next up, we've got the or gate. This
Speaker 1: one will produce a zero output if both inputs are
Speaker 1: also zero, so any other combination will create a one output.
Speaker 1: It's kind of the opposite of the AND gate in
Speaker 1: many ways. Then we have the exclusive or, which is
Speaker 1: agreed not to date other people. I'm sorry, that's the
Speaker 1: nighttime advil talking. The exclusive or x or produces a
Speaker 1: one only if one input is a one and the
Speaker 1: other one is a zero. So if you have one,
Speaker 1: zero or zero, one is the inputs that produces a
Speaker 1: one output. The zero zero and one one inputs would
Speaker 1: produce a zero output. I know this starts getting confusing,
Speaker 1: but this is just for the purposes of explaining the
Speaker 1: different types of logic gates. Next up, we've got the
Speaker 1: logical inverter. So a logic inverter is someone who stands
Speaker 1: mister spot on his head. No, actually no, it's a
Speaker 1: not git and this only has a single input. So
Speaker 1: it's one of those exceptions I was talking about a
Speaker 1: few moments ago. So an inverter does exactly what you
Speaker 1: would expect. It produces an output that's the opposite of
Speaker 1: the input. So if you have a one coming into
Speaker 1: a not git, a zero is coming out, or vice versa.
Speaker 1: Now we're going to get into a few gates that
Speaker 1: combine some of the more simple verse into something a
Speaker 1: little more sophisticated. So first up, we've got the nand gate,
Speaker 1: the NA in D gate. This behaves as if it
Speaker 1: is an and gate immediately followed by a not gate.
Speaker 1: So the nand gate will create a zero output only
Speaker 1: if both inputs are one, so one one creates a
Speaker 1: zero output. Any other combination would produce a one output.
Speaker 1: Then we have the nore gate, which is an or
Speaker 1: gate followed by an inverter. It will only produce a
Speaker 1: one if both inputs are zero, So zero zero creates
Speaker 1: a one output. Every other combination creates a zero output.
Speaker 1: Now let's go crazy Broadway style. We got the exclusive
Speaker 1: nore or x nore gate, which will produce an output
Speaker 1: of one if both inputs are the same. So a
Speaker 1: zero zero input will create a one output, but then
Speaker 1: so will a one one input. Now a one zero
Speaker 1: or a zero one input that would create a zero.
Speaker 1: So yes, I know that sounded like a lot of
Speaker 1: zeros and ones, but that's what we've got to work with.
Speaker 1: And these logic gates are what make up digital circuits.
Speaker 1: You can combine them in all sorts of different configurations,
Speaker 1: with the only real limit being that we are talking
Speaker 1: about physical structures producing these outputs, right, we are talking
Speaker 1: about actual transistors and resistors. So eventually you do start
Speaker 1: to run out of physical space. So they do take
Speaker 1: up space, very little space because these are very very
Speaker 1: very tiny components, but they do take up space. You
Speaker 1: also run into issues like how much heat you're producing
Speaker 1: when you're providing power to the circuit, so that can
Speaker 1: also be a limiting factor, but otherwise you can get
Speaker 1: into lots of complex orientations and configurations. Now, the cool
Speaker 1: thing about this is you could actually write out the
Speaker 1: string of logic gates that your circuits follow. Though you
Speaker 1: would need an awful lot of paper to do anything
Speaker 1: like a modern circuit, you could do it, however. The
Speaker 1: point is that logic gates represent specific rules, and these
Speaker 1: rules determine the output produced based upon the input received.
Speaker 1: And that's the very basic foundation of digital computers. Though
Speaker 1: obviously it gets a lot more complicated from there, but
Speaker 1: that's something I'll just have to tackle on a day
Speaker 1: when I'm not on ADVILPM, which is not a sponsor,
Speaker 1: I should add, it's just the reason this episode turned
Speaker 1: out the way it did, so my apologies on that one. Anyway,
Speaker 1: that's the basics of logic gates. You can get a
Speaker 1: lot more detailed, as I said, and I know it
Speaker 1: gets really confusing hearing all those ones and zeros. I
Speaker 1: recommend looking up truth tables for different logic gates so
Speaker 1: that you can get a better understanding. It helps me,
Speaker 1: at least when I'm able to see visualizations of this
Speaker 1: in various charts, and that lets me get a better
Speaker 1: understanding of what output you're going to get based upon
Speaker 1: the input going in. So yeah, this is like the
Speaker 1: core foundation of processing. So you combine that with the
Speaker 1: element of binary information where your values can either be
Speaker 1: a zero or one. Then you start grouping bits together
Speaker 1: to make more meaningful representations of info. Couple that with
Speaker 1: the process of logic gates, and you start to see
Speaker 1: how computers actually start physically handle this information in the
Speaker 1: form of voltages. It's really incredible, like when you start
Speaker 1: to break it down, because we deal with such an
Speaker 1: abstraction of what computers are doing when we're running any program, right,
Speaker 1: We're just focusing on whatever the program does. We're not
Speaker 1: necessarily thinking what is going on at the circuit level
Speaker 1: to make this happen. Well, logic gates are really the
Speaker 1: basis for that. So I hope this was interesting. I'm
Speaker 1: sure it was at least cringe worthy and maybe in
Speaker 1: a retaining as well due to my aduled state thanks
Speaker 1: to the nighttime medication I accidentally took. And it's still
Speaker 1: doing a number on me, y'all. I've had two full
Speaker 1: cups of coffee to push through this, So blame my
Speaker 1: foolish on grabbing the first headache medicine that I wasn't
Speaker 1: within reach for me to deal with my headache. That's
Speaker 1: the reason. All right, We've got a couple more new
Speaker 1: episodes this week before we get into rerun territory. I've
Speaker 1: got a new episode for tomorrow and for Wednesday, so
Speaker 1: hope you enjoy those. They will also be on the
Speaker 1: shorter side, which was necessary for me to be able
Speaker 1: to get everything done before I headed off on vacation.
Speaker 1: And I hope you are all well. I hope I'm
Speaker 1: well right now. I should be kind of leaning back
Speaker 1: in a hammock in the Blue Ridge Mountains somewhere hopefully
Speaker 1: at this point, unless the weather's terrible, which is probably
Speaker 1: will be, and that case, I'll just be inside watching
Speaker 1: the rain. Either way sounds good to me. And I
Speaker 1: will talk to you again really soon. Tech Stuff is
Speaker 1: an iHeartRadio production. For more podcasts from iHeartRadio, visit the
Speaker 1: iHeartRadio app, Apple Podcasts, or wherever you listen to your
Speaker 1: favorite shows.