Hardware – Understanding Technology – by CS50 at Harvard

use a computer most every day. But what’s going on inside of
that laptop or that desktop. Well, inside of a computer
are all these 0s and 1s. And you may have heard,
indeed, that computers only understand 0s and 1s, or the,
so-called, binary system. But if computers today
can do so much, how can they do so much if they can
only speak 0s and 1s and not even the entire alphabet
that we humans have. Well, consider this. Back in our human world, you might
recognize a pattern of symbols like this as the number 123. But why is that? After all, all I did was draw
three shapes, really, three glyphs, or three symbols or
digits on the screen. But each of these digits
has some predefined meaning. If, in fact, if you went to grade school
like I did and you learned numbers in this way, odds are, you might
recall, that this rightmost column is the so-called
one’s column or one’s place. Then this is the ten’s place. And then this is the hundred’s place. Now why is that significant? Well, the reason that 1, 2,
3– that pattern represents the number we humans know
is 123 is that there’s a bit of arithmetic going on here. This, after all, means that you
should do 100 times 1 plus 10 times 2 plus 1 times 3. That, of course, gives us
100 plus 20 plus 3 or 123. In other words, there’s a
pattern to these digits, and there’s a meaning
behind each of their places. Well, it turns out that computers
only, indeed, understand 0s and 1s. They can’t count as high as 2 and 3
and 4 in the same way we humans can. But they use those 0s and
1s in exactly the same way. In fact, consider this. If we consider this pattern 0,
0, 0, to be inside of a computer, and that’s what the
computer is thinking, well, what number might this be. Well, the spoiler is
that this is actually going to represent just 0, thankfully,
just like in our human world. But why is that the case? And how can we count higher than 0? Well, in the computer world,
realize that these places are just a little different. This is still the one’s
place, but this next one is not the ten’s place anymore. It’s, instead, the two’s place. And this next place is not
the hundred’s place anymore. It’s, instead, the four’s place. And if you think about this,
there’s still a pattern. Previously, it was 1, 10, 100,
and then if we kept going, 1,000, 10,000 100,000, and so forth. And here, too, there’s a pattern. 1, 2, 4– and if I kept going– 8, 16, and 32. And so, in our human world,
we tend to use powers of 10. 10 to 0 is 1, 10 to the 1
is 10, 10 to the 2 is 100. And in the computer world, this
is 2 to the 0, which is 1, 2 to 1, which is 2, 2 to the 2,
or 2 squared, which is 4. 2 to 3 would be 8 and so forth. So all we’re doing is changing the
base that we’re using, so to speak. Instead of powers of 10,
we’re using powers of 2. And so why is this number 0, 0, 0 the
number we humans know as 0 itself? Well, again, if we just do the math, 4
times 0 plus 2 times 0 plus 1 times 0 is, of course, 0 plus 0 plus 0 or
the number we humans know as just 0. Well, what if we do
another number altogether? Suppose we do this pattern 0, 0, 1. Well, what number does this represent? Well, if you consider the same columns– 1, 2, and 4– this means we have four times 0, which
is 0, 2 times 0, which is 0, 1 times 1, which is 1. So this is the number
we humans know as 1. All right. So not all that interesting yet,
but what about the number 2? How, in binary, bi meaning two, and the
2 being a 0 and a 1, how, in binary, can I now count as high as 2? Well, if this is my one’s
place, this is my two’s place, and this is my four’s place, what digits
do I want to put below those places if the only digits I have at my
disposal now are not 0 through 9, but just 0 through 1? Well, I don’t need a 4,
so I can make that a 0. I do need 2 if I want to count
to the number we know as two, so I’m going to put a 1 there. And I don’t need an extra 1
because an extra 1 would give me 3. So I’m going to do this. And so a computer, to
store the number we humans know as two in decimal which
store it in binary as 0, 1, 0. Because that’s 4 times 0 plus
2 times 1 plus time 1 times 0, which, of course, is going
to give me the number 2. What about 3? Well, in the world of
computers, if we again have our one’s place two’s
place and four’s place, how do I now arrange my zeros and ones
to give me the number we know as 3? Well, let’s see I don’t need a 4. That would be too big. I do need a 2, and I do need a 1. And that is now going to give me 3. Because 2 times 1, 1 times 1 is
2, 1 times 1 is 1, 2 plus 1 is 3. Now what about 4? How do I count as high as four? Well, it’s even easier, perhaps because
we just need a single 1 in this case. We just need 1, 0, 0. Because now I have one
1 in the four’s place. And now let’s skip ahead. Suppose I want to count up
as high as, let’s say, 7? What do I do? Well, 7, let me take a byte out of that. So this gives me 4. Let me take a two, that
gives me 4 plus 2, that’s 6. Let me give myself another 1. 1, 1, 1, in binary, equals 7. Now what about a number like 8? I can’t seem to count as high as 8
unless I give myself another bit. But that’s OK because,
just as in the human world, if you have not a three-digit
number, but a four-digit number, you simply add another place. So it might be the ones column, the
tens, the hundreds, the thousands. In this case, though, it’s going to
be the ones, the twos, the fours, and the eights. And so if we want to count
as high as 8 in binary, we might do 1, 0, 0, 0, which,
of course, gives me 8 times 1. And then everything else is 0. So that gives me the number 8. So even though computers
only speak 0s and 1s and only understand the
so-called binary system, they can still count as
high as we humans can. And they fundamentally do
it, really, in the same way. It’s just that they have
a smaller vocabulary. But why do they have
a smaller vocabulary, especially when they can do so much? Well, it turns out that,
in the physical world, it’s just convenient to be able to
represent only two states instead of 10. And by states, I mean
digits, in this case. It’s a lot easier in
the human world, not to represent 10 possible
values 0 or 9, but just two– 0 and 1. And we could have called those
digits anything we wanted, but we humans just standardized
our numbers like that. But 0 and 1 is nice because if you think
of one of these binary digits or bits as just being a light bulb–
it’s either off or on. You can think of a 0 as
a light bulb being off and a one as being a
light bulb being on. And light bulbs, of course, in our human
world just need electricity to run. And so, if we somehow get electricity
into our computer laptop, desktop, or whatnot coming from the power
outlet in the wall or some battery, well, that would seem to be
sufficient input in order to turn a light bulb on or off, to
turn a switch, really, on or off. And indeed, that’s what’s inside
of our computers– transistors, otherwise known as switches. And these transistors, which now
number in the billions in the most modern of computers are tiny,
tiny, tiny little light switches, if you will, that, if turned on,
allow us to store 1s, if turned off, allow us to store 0s. And using those many,
many, many transistors, can we store values, can we
store data, can we compute, and can we actually do everything we
can today with our modern computers. Let’s make this more real and
try out some actual light bulbs. So here are some light bulbs
clamped into these desk lamps. And suppose now that I
have these light bulbs here to represent bits or binary digits. So each of these light bulbs
can represent a 0 if it’s off or a 1 if it’s on. And if we think about the same
system that computers use, let’s think of this bulb here as
being the one’s place, this bulb here as being the two’s place and this
bulb here as being the four’s place. So what number am I
currently representing if all of these light bulbs are off? Well, that’s like having 0, 0, 0. Since they’re all off, so that’s the
number we humans know in decimal, dec meaning 10, as 0. What about if I turn on just
this one light bulb here? What does that represent? This, again, is the one’s place, the
two’s place, and the four’s place. So this, of course, represents
the number we know as 1. Now, if I go ahead and
simultaneously switch these, this is still the one’s place, the
two’s place, and the four’s place. So what is this? This, now, is the number we know as 2. How do I count as high as 3? I don’t want to keep
going down the line. Instead, I want to turn this 1 back on
because that means I get a 1 plus a 2. I don’t need the 4, which is
great, because now I have 3. How do I get to 4 then? Well, let me turn both of these off,
turn this one on, and now, of course, this is the four’s place. So this is a 4. If I turn this one back on, now we’re
up to a four’s place and a one’s place, so that gives me 5. If I turn this off, this on, that
gives me a 4 plus a 2, or a 6. And finally, if that
turns on, I have now a 7. Unfortunately, I can’t
count as high as 8 unless I go get myself
another desk lamp, but for that we just need another bit. But this is all very fine and good, but
all I can represent thus far, it seems, are numbers. How, though, do I represent letters
of the actual alphabet, A through Z? How do I represent
words or paragraphs, let alone emails, and any number of other
features that computers today support? Well, for that, we’re going
to need to make a decision. We’re going to need to
decide what patterns of bits to use to represent those higher
level notions like letters words and paragraphs. So for that, I’ve got an idea. So at the end of the day, all computers
can store is, indeed, 0s and 1s. And from those zeros
and ones, of course, can we count higher so long as we have
a mapping from binary to the numbers we know as decimal. But, of course, we want
our computers to do more. We want to be able to express
words and even other types of data. So how do we do that? Well, we need to come up with
a standardization, a mapping, from 0s and 1s, or really just
numbers, to the letters that we want. And it turns out, that some years ago
what humans decided to do was this. Now, at first glance, this
might be a little overwhelming. This is just a screenshot of
a chart from asciichart.com. An ASCII chart is a chart of ASCII
characters, American Standard Code for Information Interchange. And this is simply a mapping
from decimal numbers to letters. And so on let’s notice a few of these. Notice here that 65 apparently maps
to A, 66 maps to B, 67 maps to C, and so forth. Meanwhile, 97 maps to lowercase a,
98 to lowercase b, 99 to lowercase c, and so forth. And there’s also mappings
from punctuation symbols to all the letters of the
alphabet that you may know. So why is this significant? Well, it turns out that even though
computers only store 0s and 1s, we, of course, use
them in different ways. We have programs like Notepad
on PCs, or TextEdit on Mac OS, or Microsoft Word on both platforms,
or Google spreadsheets, or Google Docs, or the like. And so we have all
these different programs that is designed to do
one thing or the other. And so those programs essentially
decide, in their own context, whether to display patterns of
bits as numbers or as letters or, in turn, words and paragraphs. So it’s entirely context-dependent. At the end of the day, all the
computer is storing is 0s and 1s, but it’s up to the program to interpret
those 0s and 1s in a certain way. And so, if a program like
Microsoft Word or Google Docs sees a pattern of bits in a file that
represents the decimal number 65– it’s still pattern of 0s
and 1s expressed in binary, but of course, we’ve seen how
we can convert that to decimal. So if a computer is ultimately
storing a pattern of 0s and 1s that represents the decimal
number 65, the computer, in this case Microsoft Word, or Google
Docs, and the program running there, is going to interpret that
pattern, not as the number 65, and not as a whole bunch of 0s and 1s
alone, but as the capital letter A. And that’s what you’ll
see on your screen. If it, instead, sees a pattern of bits
that represents the decimal number 66, Microsoft Word or Google
Docs is going to show, instead, the capitol letter
B. If the pattern of bits instead represents
the decimal number 97, that program is going to display
the lowercase letter a or any number of other letters from the alphabet. And so we just had to decide
in advance what mapping to use, what code to use that
maps numbers to letters. And in fact, you’ll notice
that quite a few characters are absent from the screen here. In fact, if you speak some language and
write some language other than English there might be some
characters that you can express with just this range of values. In fact ASCII originally
only used 7 bits total. Or if you round up, 8 bits total,
for what’s called the extended ASCII. And it turns out, that’s not nearly
enough patterns of bits, 256 maximally, that you can use to express
characters that you might see in certain Asian languages or
symbols that just simply are not depicted even yet on the screen here. So there are other
systems, not just ASCII. Something called Unicode, for instance,
is a superset of what you see here. And that actually allows us to
express any number of characters from English and Asian languages
and beyond and, in fact, even things like the emoji
characters– the smiley faces, and other such characters that
you might now use increasingly on your phone, your desktop, or laptop. Those two are expressed ultimately
as just patterns of bits. And the world, for the
most part, has simply standardized on what
pattern of bits represents a happy face, what pattern of
bits represents a sad face, and beyond, in that
system there is Unicode. So let’s take an example. Suppose that you see this pattern
of bits somewhere in a file. And you, in this context, say are
Microsoft Word, or Google Docs, or some program designed to display,
not numbers like a calculator, but words and letters like a
word processor or a text editor. Well, what is this pattern of bits? Well, we haven’t seen
this many bits before, but it looks to be like
two patterns of eight. And in fact, it turns out that anytime
you have eight bits here or eight bits here, humans generally refer
to this as a byte, B-Y-T-E. So a byte is just eight bits. And it’s a slightly more
useful measure because it’s a lot bigger than a single bit, which
can, of course, only represent 0 or 1. A byte can actually count higher. So what are the columns here if we
look only at this number at left? This is my 1’s place, 2’s, 4’s, 8’s,
16’s, 32’s, and 64, and then 128. So 64 plus 8, if I do that
arithmetic, that gives me 72. Now let’s consider the
pattern of bits on the right. Again, my 1’s place, 2’s place,
4’s 8’s, 16’s, 32, 64, 128. Now notice, these patterns
are actually almost identical. We’ve got a 1 in the 64’s place,
we’ve got a 1 in the 8’s place, but we’ve also got an
extra one in the 1’s place. So if this was 72, and this pattern
is identical except for this last bit here, which adds 1, this
must be 72 followed by 73. And I’ve put a space
here, visually, just to separate the fact that these
are, indeed, two separate bytes. And I claim now that, yes,
while you could interpret these as two decimal digits, 72 and 73,
it turns out, per the ASCII system, we could map 72 and 73
to alphabetical letters. What might those letters be? Well, if we consider our
chart again, 72 apparently gives us a capital H. 73
gives us the capital I. And, voila, 72 followed by 73 in
a computer’s memory, apparently, is how a computer would express HI. And of course, if we used more bytes,
and therefore more bits, and therefore more numbers, we could represent even
larger words than just H I, or HI. But that’s exactly how a computer,
underneath the hood so to speak, would store a word like HI. Now what is indeed using
these patterns of bits? And what is a computer actually
doing at the end of the day? Well, for that, we need to take a
look under the hood, so to speak. This is what Intel inside means. If your Mac or your PC
comes with an Intel Inside, as goes the marketing slogan, that means
that your computer has inside of it a CPU, a Central Processing Unit that
looks a little something like this. It’s a pretty small device. It’s not quite as big as this. This, of course, is not to scale. It wouldn’t fit in your
actual laptop or desktop. But what you see is two sides. This is just a mental case
and a nice big logo there. And then, if you flip this
around, you see the other side, which generally has a
whole bunch of golden pins that actually interconnect to a
device inside of the computer. And now what is that device? Well, that device, we’ll soon see,
is something called the motherboard. A motherboard is a circuit
board, so a big piece of silicon or plastic-like
material that has a lot of lines running
back and forth on it, and often has sockets, essentially,
a bunch of tiny little holes into which devices like this fit so that
you can put this inside of a computer and actually have it
clamped down on something. Now what does it mean to be a CPU? Well, the CPU is the
brains of your computer. It’s the thing in your
computer that does all of the work, all of the thinking. Now what kind of thinking
does a computer need to do? Well, if you’re feeding
it all of these numbers, and you’re feeding it
all of these letters, you want to maybe perform
math on those numbers. You might want to display
those letters on the screen. You might want to add
or delete those letters if the user is using a word
processor and typing new characters or hitting delete. And so a computer needs to do all of
that thinking and work for the human. And the peace inside of the
computer that does most of that work is, indeed, this device
here called the CPU. Now, it turns out, that CPUs today
are actually getting pretty fancy. And inside of a CPU, typically,
is one or more cores, so to speak. And a core is really
what’s doing the work. And it is the device inside
of this device that actually can do addition, and subtraction,
and multiplication, and division, and other operations still
loading information from memory, saving information to memory. And so a CPU like this might have
one, or two, or four or more cores, which means it can do one, or two,
or four or more things at a time. And that’s great because,
these days on my Mac or my PC, I might double-click a
whole bunch of icons. I might be running multiple programs. I might be chatting
with a friend over here. I might be working on
my homework over here. And so I might have a lot of programs
and a lot of files open simultaneously. And thanks to multiple cores inside
of a CPU, can each of those programs continue running in parallel. Maybe one is printing
something to my printer. Or maybe one is playing back a video. Maybe one is spell-checking a file. Any number of operations can
literally be happening simultaneously. Now moreover, it turns out
that the fanciest of use today, from Intel especially, also support
something called hyperthreading, which means you might just
have one CPU or one core, but thanks to some technology
built into the CPU itself, it will present itself to the
computer, to the operating system, Mac OS or Windows–
more on those in a bit– as though it’s actually
two CPUs or two cores. And so, thanks to technology,
can your computer actually think it has even more computational
power than it actually has, thereby allowing it to
take advantage of downtime or slow running programs
that might still allow you to run multiple things simultaneously. But we’ll come back
to that in just a bit. Now, not all devices have just a
CPU connected to a motherboard. Some devices, instead, have a CPU and
more all interconnected all at once. And these things are generally
known as systems on a chip. And they’re especially popular in
things like tablets or iPads these days, game consoles like Xboxes or even
things like the Raspberry Pi, which is a very small computer
that looks pretty much like this. Also not to scale, this thing
could fit in the palm of my hand. And this has, not only one of
these silicon circuit boards– generally green, and you’ll see
there’s very fine lines or traces that interconnect all of the
chips and technology that’s plugged into this
thing– and it also has, well, first and foremost, no case. There’s no pretty plastic case that
protects all of these components. It really is just a
raw piece of hardware that computer technophiles like
to use to build their own machines and programs. But it has a whole bunch of ports– as we’ll return to in a
bit– a whole bunch of places you can connect other devices. But these systems on a
chip all come together. And they do many things beyond
just the CPU’s task alone. But what else is inside
of your computer? Well, the CPU is the brain. And the CPU on a system on
a chip is thereto the brain. But there’s other components
necessary inside of a computer so we can do actual work. And one of those things is called
memory or random access memory. And random access memory
looks, physically, like this. This is a chip that you might slide into
a little slot inside of your computer specifically on the so-called
motherboard, again, a big greenish board into which all of your
computer’s components connect. And there’s usually a little divot
here, a little bump to make sure you put it in the right way– instead
this way, instead of, for instance, that way. And then on this green circuit
board are all these various chips that actually store your data. Specifically, they store your data in
a volatile way, only when the power is on, when your laptop has
battery and is running or when your laptop is
plugged in and is running. Which is to say, when you
double-click an icon on the screen or run some program, open
some file, those files are loaded into the little black
chips that you see on this stick here. They’re loaded into RAM
or Random Access Memory. And this memory is pretty fast. And it is where those
files and programs live, so long as you are using them
at a given moment in time. Now other devices have slightly
different looking sticks of RAM. This is a smaller stick
here that’s actually found, typically, in laptops or certain
desktop models, but it’s the same idea. It’s simply a different form factor. Now you can actually
see in your Mac or PC sometimes exactly how much
RAM you have, especially if you bought the computer
without knowing this concept or were given the computer
and didn’t think to ask. In fact, on Windows, if you open
up the so-called Task Manager and look at the CPU tab, you might
see a little something like this. You’ll see one, a nice little chart
that shows you what your CPU has been doing over the past few seconds. And the higher these peaks
are, the busier it was. Maybe you double-clicked
an icon or played a video or sent a really big email
or something like that. But more interesting, down
here, is the speed of your CPU. This one is 1.9 for gigahertz. And a gigahertz means 1
billion things per second. So a you that’s 1.9 for gigahertz
means that this computer, this CPU can do 1.94 billion things per second– additions, subtractions,
multiplications, printing to the screen,
any number of other things. But if we look, odds are this is
marketed, frankly, as 2 gigahertz, and maybe it has burst technology
whereby it can actually go even a little faster,
maximum speed 2.81 gigahertz by maybe using a little
more energy for some amount of time and therefore generating
a bit more heat. But you’ll see that there’s only one
socket in the computer from which I took this screenshot from Windows,
which means there’s one CPU. But that CPU has two cores, which means
that the computer can do literally two things at once because it has
really two brains inside of that device that we saw a picture of a moment ago. But logically, it actually seems four. So this particular windows computer
has a CPU with two cores, each of which supports that technology
called hyperthreading, which means that each of those cores will
present itself to the Windows operating system as though it’s two. Which is to say each core will
do two things simultaneously, thereby giving me four logical
processors or, really, the ability to do 4 total things at once. So perhaps lower level detail
than is perhaps germane, but these are the kinds of things
that you end up paying for in a store or when you buy a computer online. This is what distinguishes a less
expensive computer from a more expensive computer is just
how fast the CPU or CPUs are and just how many cores
the CPU has and, therefore, just how much work you can get
done at a given moment in time or just how quickly you
can work more generally. Now, in a Mac, if you open
up your System Profiler, you’ll see a different kind of
interface, but similar information. This is taken here from a MacBook Pro. You can see that this CPU
is 3.1 gigahertz, so faster, but it has one processor,
total number of cores is two. And so, here, we see no mention of
hyperthreading, which generally windows is a bit more detailed on, but this does
mean that this CPU is pretty darn fast, 3.1 billion things per second. And it actually has two cores, so it
can do at least two things at once. All right. So that’s my CPU, which does all
the thinking and all of the work. That’s RAM or random access memory
where all of my data and programs are stored while I am using them. So what else do I need? Well, where are those programs and
files stored when the power is not on or when my battery is dead or when
my computer is not even plugged in. Now, odds are, if your computer is like
mine, you don’t lose all of your files and all of your programs just
because your battery dies or you move a computer, and
therefore, unplug it from the wall. It would not be a very useful device. Computers do have nonvolatile
memory that sticks around even when the power is lost, but
it uses a different technology than RAM for that. It tends to use a disk or a
hard disk, as in this case. So this is a device that a PC desktop
or Mac desktop might have inside of it. And it actually stores quite a bit
more information than a stick of RAM. A stick of RAM might store one gigabyte,
two gigabytes, maybe even 16 gigabytes. But a hard drive, as
this thing is called, will actually store 256 gigabytes,
or maybe 1,000 gigabytes, AKA a terabyte or even two
terabytes or four terabytes, which is an order of magnitude
more than our sticks of RAM. Inside of this device,
though, meanwhile is something that feels kind of old school. It’s actually one or more
metal platters that literally physically spin around mechanically. And on those platters is
your data actually stored. So in RAM, there were no moving parts. There is no fan, there’s no motor,
there’s nothing to move back and forth. It’s entirely electronic. It’s all electrons at
the end of the day. But a hard drive is a mechanical
device that actually has one or more of these platters spinning
and spinning and spinning. And that’s what allows
the computer to access different areas of those platters. And, in fact, you’ll see one or
more of these little reading heads, not unlike old school
phonograph or record players that actually
move back and forth and read the data from that device. And what’s nice about this
device is that it’s nonvolatile. It uses tiny, tiny magnetic particles,
little specks of magnetic particles, that, if you orient them
this way might represent a 1. If you orient them this way it might
represent a 0– so north to south pole, south to north pole if you
remember some of your electronics. But all that is to say is there’s tiny,
tiny, tiny little particles on here, billions or more perhaps, that,
depending on their orientation up or down, represent a 1 or 0. And if you have enough
of those particles, you can represent bytes or
megabytes or gigabytes or terabytes or more or anything in between. And so you have the ability
to store data this way or this way, even when the power is off. The power is used just to read the
data or to write or change the data. It doesn’t need to stick
around to persist the data. So in fact, why don’t we take
a look at what this motor looks like when actually running. This is a short video from the
Slow Mo Guys, which gives us a sense of what the hard drive
looks like when its lid is indeed removed like that there. [VIDEO PLAYBACK] [END VIDEO] DAVID J. MALAN: Fascinating. I know. Well, now let’s actually take the
hood off of an actual hard drive, albeit via animation, and actually see
and hear what it is that’s going on. And in this depiction here, you’ll see
that the magnetic particles ultimately are represented as red-blue,
or blue-red particles, which represent precisely those
magnetic particles that represent your 0s and 1s. [VIDEO PLAYBACK] – The hard drive is where your PC
stores most of its permanent data. To do that, the data
travels from RAM along with software signals that tell the
hard drive how to store that data. The hard drive circuits translate those
signals into voltage fluctuations. These, in turn, control the
hard drive’s moving parts– some of the few moving parts
left in the modern computer. Some of the signals control a motor
which spins metal-coated platters. Your data is actually
stored on these platters. Other signals move the read-write heads
to read or write data on the platters. This machinery is so precise
that a human hair couldn’t even pass between the heads
and spinning platters. Yet, it all works at terrific speeds. [END VIDEO] DAVID J. MALAN: So where
are those particles? Well, for that, we’re going to have to
zoom in even closer because they’re not visible to the human eye. [VIDEO PLAYBACK] – Let’s look at what we
just saw in slow motion. When a brief pulse of electricity
is sent to the read-write head, it flips on a tiny electromagnet
for a fraction of a second. The magnet creates a field
which changes the polarity of a tiny, tiny portion
of the metal particles which coat each platter surface. A pattern series of these tiny
charged up areas on the disk represents a single bit of data in the
binary number system used by computers. Now, if the current is sent one
way through the read-write head, the area is polarized in one direction. If the current is set in
the opposite direction, the polarization is reversed. How do you get data off the hard disk? Just reverse the process. So it’s the particles on the
disk that get the current in the read-write head moving. Put together millions of
these magnetized segments, and you’ve got a file. Now, the pieces of a single
file may be scattered all over a drive’s platters kind of
like the mess of papers on your desk. So a special extra file keeps
track of where everything is. Don’t you wish you had
something like that? [END VIDEO] DAVID J. MALAN: Now, anytime
you have a physical device like this that’s spinning
all day long or for months on end, if you use your computer a lot
and for quite a long period of time, something could go wrong. Maybe you accidentally bump the desktop
or the laptop, the result of which is that this reading head might
actually strike the platter and make a dent in it or some kind of
scratch which actually will corrupt, not only some of the data
perhaps, but might even stop the whole device from working if
the reading head no longer functions properly. Moreover, anything
that’s physical like this isn’t going to spin all that
fast at the end of the day. Now technically, a hard drive like
this might spin 7,200 times per minute or even 10,000 times per minute,
but that’s much, much slower than the speed with
which electrons travel as they would in something like RAM. Well, fortunately, it
turns out that there’s something in between those technologies
that doesn’t have moving parts, but that’s not quite as fast as
RAM, but that is non-volatile, whereby it will store
your data persistently even when the power is off. And this is so-called flash memory or
a Solid State Disk, SSD, in this case here. It’s a smaller device, whereas typical
hard drives that have moving parts are very often 3 and 1/2
inches, although 2 and 1/2 inch versions do exist as well, in diameter. A solid state drive tends to
be only 2.5 inches in width so that it actually fits inside
of computers in the same slots that older more mechanical
hard drives might fit. But it doesn’t have moving parts. In fact, if we open it up, you’ll see
something very reminiscent of the RAM we saw earlier. But the technology inside of this
device is such that the data persists, even when your battery dies or
you unplug your laptop or desktop. But the upside of an SSD, being entirely
electronic, is that it’s much faster. And so this means that
your programs will load faster when you
double-click them, your files will open up faster when
you double-click on them. Anything you might do or save to
your hard drive or solid state drive, in this case, will actually get
saved much more quickly, which means you might see a little hourglass
or spinning beachball much less frequently. And your computer is going to
behave and certainly feel faster. Now the catch is that solid
state drives, theoretically, won’t necessarily last as long,
depending on the quality of the brand and the technology being
used whereby they only have a finite number of writes. You can read from them
nearly as much as you want. But over time, they’ll degrade
in terms of how many times you can keep writing to them. Now, for many people this
might be a non-issue, but to mitigate against this, has
the industry also introduced what are called hybrid drives– hard drives that might be the
same size as this or the same size as a 3 and 1/2 inch drive like
the spinning mechanical device we saw a moment ago in our animated form– but they might have both
some solid state memory and some mechanical hard drive memory
so that you might have a few megabytes or gigabytes of solid state memory. And you might have a few gigabytes
or terabytes of traditional hard disk space. And the device itself moves
your data around in a clever way so that it tries to keep as
much of the data that you want to use, at a given moment, on
the solid state part of the device so that it’s readily accessible for you. And the data that you might
not need, right then and there, stays on the slower,
more mechanical device where, nonetheless, you
have a lot more storage. Now flash memory is something you
might have heard about before now, but in the form of
these things here, USB sticks that might store 1
gigabyte or 16 gigabytes or more. But it’s data that you might want
to carry around on your keychain or in your pocket or keep
around on your desk simply for transferring files from
one computer to another or keeping some data with you. They tend to be slower though,
than solid state drives. They tend to be less reliable. But they also tend to be much
less expensive, but also smaller in capacity. But the technology is
very similar in spirit. If you need more
storage space than that, you might actually carry around with
you a solid state drive externally. So it might be a little
bigger, and a little heavier, and not something you want
to put on your keychain. But this might store
256 gigabytes of space or even a terabyte of space, all of
which is now carried around externally. And via some kind of cable
can you plug this device into your laptop or desktop or maybe
a friend or colleague’s computer so that you can share files
without having a local network. If you need even more storage than that,
1 terabyte, 2 terabytes, 4 terabytes, or more, you might actually have
another type of external hard drive inside of which is one of those older
more traditional mechanical drives, the 3 and 1/2 inch disk devices, that
might store much, much, much more data. But the price you pay is that
it’s a mechanical device. It might be, therefore,
a little bit slower. And so ultimately,
there’s this trade-off between how much space you get,
how much money you’re spending, and how quickly you can get data
from and to that external device. In fact, there’s this whole series of
trade-offs that we’ve seen thus far. And you can actually think
of these various types of memory inside of a computer
like a funnel of sorts whereby you have a pretty big opening
where you keep a lot of your data on the biggest of your devices. But the goal is to get that data
closer and closer and closer to your computer’s brain where
it can do some actual work. Indeed, if you think of the CPU as
being at the bottom of this funnel, that’s to whom you want
to get all of this data. So throughout this funnel, you might
have your hard disk or your solid state disk up here which stores a lot of
your files a lot of your programs persistently in a nonvolatile way
so that it’s permanent even when the power or battery no longer works. But that hard disk or solid state
disk ultimately feeds information down to your computer’s RAM. But the ram is not the last
stop before the computer’s CPU. It turns out that there’s
other types of memory that a computer has that you might even
see mentioned on your computer screen. So if up here you have
your disk, whether it’s a hard disk drive or a
solid state disk drive, you might have quite a bit of this. This might be in the order of gigabytes
or terabytes, billions of bytes or trillions of bytes. That gets fed into, ultimately, your
computer’s RAM, which probably exists on the order of these days of
gigabytes, but fewer gigabytes than your actual disk. Down here you’re going to have your CPU. And indeed, the goal is to
get your data to the CPU. And the CPU, of course,
is measured not in bytes but in gigahertz– the
number of billions of things it can do per second with that data. But there’s also tends to be
something in between RAM and CPU. There’s often something called
Level 3 cache, which might exist in the form of megabytes worth. Then it goes into what’s
called Level 2 cache, which is another type of
memory, which also might be in the kilobyte or thousands
of bytes or megabyte range. And then there might be L1
cache, which doesn’t quite fit on this on the screen. But that’s OK. Because it hints at just how small
of a physical device this is, which might be on the
order of, say, kilobytes. So these values will vary. And they’ll certainly change over time. And so what’s the pattern, then,
among these various types of memory leading to the CPU? Well, the disk, whether a
hard disk or solid state disk, is not only nonvolatile–
sticks around permanently, and it’s where your files and your
programs are stored when the power is off– that’s the biggest of these
various types of memories, but it’s also the slowest. Even solid state is slower than
some of these other memories below it on the funnel here. Meanwhile, RAM tends to exist,
still on the order of gigabytes, but maybe 1 gigabyte, 4
gigabytes, 16, maybe more if you’ve splurged on
a really nice computer. But RAM recall is where
programs and files live when you double-clicked or
opened them in order to use them on your computer at a given moment. Meanwhile though– and this
is values you don’t really control because they tend
to be associated closely with the CPU or the
motherboard that you’ve bought as part of your computer– that
RAM feeds information into Level 3 and/or Level 2 and/or Level 1 cache in
turn so that it’s less memory there, but it’s super, super fast. And that ensures that, even though
there’s less of this memory– Level 1 cache exists in smaller
quantities than Level 3– that funnel is just always filled. There’s always something
at the bottom of the funnel ready to be fed into the CPU. So the CPU never, theoretically,
has to wait for any data– to get numbers to crunch, or
text to display, or the like. Meanwhile, there exists,
turns out, tiny little pieces of memory in a computer that we’ll
give a name to called registers. And these registers typically only hold
1 byte or 4 bytes or 8 bytes total. So they’re the smallest unit of memory. But it’s in those registers
that the CPU stores values like numbers like those decimal
numbers we discussed earlier. And if it wants to perform
arithmetic of any sort, it stores those values in these
registers, actually performs the math, stores the result in another
register, so it’s, then, ready to be loaded back through this funnel
into something like the computer’s RAM or ultimately saved back to disk. But there’s another trade-off here. Besides the top of this funnel
being bigger and slower, and the bottom of this funnel
being smaller and faster, the bottom of the funnel also
tends to be more expensive, which also explains, in
part, why you see less of this memory inside of a computer. The Level 1 cache might be
more expensive than ram, so you have less of it and,
technically, you don’t even need as much of it so long
as there’s enough to keep data waiting for the CPU. But cost is certainly
another trade-off as well. But the types of numbers that you, as
a consumer, might care about, really, would be how big the
disk in your computer is and how much data and programs
and files you can store, how much RAM your computer has. Because that correlates
with just how much work you can do at once, how
many files and programs you can keep running simultaneously
without having to quit any of them. And so cache, finally,
which is more closely tied to the CPU and the motherboard
in your computer and, therefore, isn’t really a number you have as
much control over as the consumer, just ensures that the
data is actually ready. Now this might all
sound fairly technical. But these caches, whether
Level 3 or 2 or 1 are actually quite similar to techniques that
we humans use in the real world, for instance, even at
your local candy store. Here’s my candy store,
and I’m open for business. SPEAKER: Candy, please? DAVID J. MALAN: Let
me get you some candy. [FOOTSTEPS] Thank you. Come again. Now that was not very efficient
to have to go all the way and back into the store
room to get the candy. Much more efficient would
be to keep it closer to me in a place that’s faster to access
much like a cache of candy right here on the counter. In fact, let me go ahead
and ready that cash. [FOOTSTEPS] And now, with this cache of candy
am I open for business again. SPEAKER: Candy, please? DAVID J. MALAN: Thank you. Come again. Now this is a small cache
of candy, but it’s fast. And, with it, can I provide my customers
or really my CPU with information much more quickly. Now we can actually see the sizes
of these caches in that same output that we saw earlier
from Windows and Mac OS. For instance, if we look again
at the Windows Task Manager and look down here, you can actually
see that this particular laptop had L1 cache on the order of 128
kilobytes or thousands of bytes. It had 512 kilobytes of L2 cache,
and 4 megabytes of L3 cache. Meanwhile, if we take a look at
that same MacBook Pro from earlier, you’ll see that it has 256 kilobytes
of cache, 4 megabytes of L3 cache, doesn’t happen to mention L1 cache, but
odds are, it’s indeed there on the CPU, just not reported by this program. Now what else is inside or
really outside of a computer? In fact, let’s start to take a look
at things, perhaps, more familiar. Now these are just graphical
depictions of connectors or sockets on the back of your computer into
which you might have very well plugged in various devices. In fact, this collection
of ports here are all related to monitors or displays. So a computer, like a
desktop computer, tends not to come with a monitor built in. And if it does, indeed not, you might
need to plug-in an external monitor using something like mini DisplayPort– very commonly found on laptops,
especially if you want to have, not just your primary
laptop display, but a secondary, a bigger
monitor on your desk– DisplayPort, which is the same
idea, but a larger connector that you might typically have on a
desktop plugging into a monitor– HDMI, which you might have, not
only on your laptop or desktop, but possibly even on your TV at home
because this is also the type of cable that you would use to plug a TV
into some kind of set-top device in your living room. And then, lastly, VGA– still on the list,
even though it’s super, super old and not nearly as featureful
as these other technologies. But you’ll very often find at
universities like this and companies that have long had projectors installed
in their rooms, this older technology, and so it, too, is still pretty common. Now, what else might we want
to plug into a computer? Well, any number of devices as well– in
fact, if you’ve ever seen this symbol, that means you have a port on your
computer, desktop or laptop, into which you can plug a whole range of devices. If you’ve ever needed to plug
a printer into your computer, you might use the port label with
this– a scanner, a digital camera, any number of other peripheral devices
might be connected to your computer by way of this device here. Even your mouse and your keyboard,
if they’re not already wireless, would be plugged in
with this device here. And it might actually
take any number of shapes, though thankfully, some of these
are more common than others. This is the universal serial bus– where a bus as a term
technologically that refers to some kind of medium along
which data can travel, much like a bus travels down a street. So USB has a whole bunch of different
connectors as depicted here. And the most common of which is
just this rectangular one that, rather annoyingly, only 50% of the
time do you, if you’re like me, plug the cable in the right way because
it can only go in one certain way. So you might have to flip it around. But on the other end of that
cable might be another type, not USB A, but USB B,
which is commonly used to plug into the back of
scanners and printers and beyond. More recently, though, have
companies like Apples and others started using using USB C– a third type of connector that,
thankfully, can go either top down or bottom up, thereby, not
having to think as much when you want to plug in a device. But there’s any number of other variants
of these connectors commonly seen on cell phones, in fact, for chargers
and data cables, all of which support USB. Now the USB standard, itself,
has evolved over time. So the latest and greatest version
of USB devices and connectors are actually much faster than some
of the historically older devices and cables. And so it actually does matter
what kind of cable you have and what device you have as to
whether or not it will transfer data as fast as you might like. Now why is this important? Well, one of the devices you can connect
to a computer, typically via USB cable, is something like an
external hard drive. And even if you have a super
fast external hard drive that is, say, an SSD underneath
the hood, if you’re using a slower older
USB cable or technology, you might not, nonetheless,
be able to transfer that data off a very fast device
over a slow cable to your computer. So keeping an eye out for the latest
versions of these technologies like USB can actually be quite important. But, of course, you might not need
cables at all for certain devices. Of course, if you want to use Wi-Fi
or wireless internet in your home, in the airport, in Starbucks,
or elsewhere, your computer just needs to support Wi-Fi, which odds
are, it very much does these days. And you might see a symbol
somewhere in your computer like this depicting as much. But not everything operates over Wi-Fi. In fact, devices that you might want to
plug into or connect to your computer without a cable would
tend to use not Wi-Fi, but another wireless
technology called Bluetooth that Windows computers and
Macs alike support these days. So in fact, if you have
a wireless keyboard at home or at work, or a
wireless mouse, or if you have any number of other devices that,
somehow, are wirelessly communicating with your computer, perhaps even
your headphones these days, odds are, those are using a technology
called Bluetooth, which have a limited range of just so many feeds. They don’t afford you nearly as much
distance as something like Wi-Fi does, but that’s a good thing. Because generally,
this technology is used to interconnect your personal
devices to your personal computer and not really to others around you. So with all of these various
devices inside of and, potentially, connected outside of
my computer, what is it that ensures that they
can all intercommunicate? And what is it that ensures
that all of this works? Well, at the end of the
day it’s the, so-called, operating system whether
it’s Mac OS or Windows, which is simply software, that
either you or, more likely, some manufacturer pre-installed
on the computer that you bought. And that software is installed on your
hard drive or your solid state disk so that it’s there persistently. And so that, even when you
unwrap that shrink-wrapped box that has had no power for some time,
the operating system is ready to go. And, indeed, when you hit the power
button on your laptop or desktop, it’s the operating system, ultimately,
that is loaded into RAM from disk, and is what you ultimately see. In fact, it’s the operating
system that gives you, literally, the graphical windows that you
see and the icons and the buttons that you can click. But more importantly,
it’s the operating system that knows how to talk to
your keyboard and your mouse. It’s your operating
system that knows how to display information on the screen. It’s your operating
system that knows how to move things around in memory
and disk and reading and writing all of that information. And that’s all thanks to software
that comes with an operating system called device drivers– special software designed to talk
to a certain model of printer, to a certain model of camera,
or scanner, and the like. And, in fact, even when Windows or
Mac OS or Linux or any other operating system doesn’t recognize some device–
maybe because it didn’t exist when Windows or Mac OS or Linux was
installed on your computer– well, you can very often download
new software device drivers from the manufacturer’s website
of the manufacturer that made that new technology. And that can teach Windows and
Mac OS and Linux and others to understand that new hardware. And so there is a future-proofing
built into these operating systems because, at the end of the
day, they’re just software. And so it’s this intersection
of hardware and software that makes these computers
just so powerful. Now, it’s all fun and good
to talk about hardware and see it depicted on the screen. But let’s actually get our hands
dirty here and actually enter into our own laboratory and
take a look on the outside and inside of some actual computers. I’m here now with Dr. Colton Ogden for
a look inside a couple of computers. COLTON OGDEN: Happy to
be with you guys today. We have an IBM ThinkPad laptop here. Nobody really needs to use it anymore. So I figured we’d show you guys what
a computer looks like on the outside before we start digging
in on the inside. So you want to start off by maybe
showing what some of these ports are here on the laptop? DAVID J. MALAN: Yeah. Sure. So here’s one of those older ports. And, indeed, this is an older laptop. This is a so-called VGA port into which
you would plug a cable to connect it, either to an external monitor, or
more realistically, on a campus or in a workplace. It’s like a projector so
that other people can see. If you can believe it, this is an RJ11
jack for an old school modem or a phone cable. So that you could
actually dial up to AOL. COLTON OGDEN: Old school. DAVID J.MALAN: Here’s
an RJ45 connector, which actually looks like this here,
as sort of a fat network cable. And that’s what you would use to
get online with wired internet. Here, we have a microphone jack, if you
have an external mic, headphone jack if you want to listen to
music at work, USB to connect any number of external devices. And oh. What’s this one we’ve got over here? COLTON OGDEN: It looks
like we’ve got a DVD port. You don’t see these very often anymore. It’s not going to work
because the laptop is off. But we also have a couple of
USB ports here on the side. And I think that’s pretty
much all we have on this guy. DAVID J. MALAN: Yeah. A DVD or CD drive is what’s
known as optical storage. And it really is just a piece
of plastic, the CD or DVD, with some reflective material on
it and little divots or pits that are created with a laser that
gets, then, read with the laser so that you can actually
write 0s and 1s by, essentially, having a smooth
surface or little bumps. But it’s increasingly falling into
disuse as Flash Media of various sorts is being used instead. Well, why don’t we not
gut this, although, I do see it’s power cable sitting here. So you’ll notice that most laptops
like this have power cables that one go into the wall, then some other
proprietary or standard connector that goes into the laptop, and then a brick. Sometimes that gets a little bit warm. And what this brick is
doing is it’s actually converting the 120 volts or 240
volts coming out of your wall to far fewer volts that your
laptop can actually tolerate. Shall we take a look
at the desktop next? COLTON OGDEN: Yeah. Perfect. So let’s go ahead and take a look at the
internals of a computer with this guy here. So I’m going to go ahead and just
take off the casing’s lid here. DAVID J. MALAN: And
this is an older PC– COLTON OGDEN: Yes. DAVID J. MALAN: –desktop right? An older Windows PC. And so you find that Mac computers
aren’t so readily taken apart. In fact, that’s one of
the features of Apple computers is that they have far
fewer user serviceable parts, but the price you pay,
of course, is that you can’t upgrade them or reconfigure
them, often using magnets to. COLTON OGDEN: Indeed. DAVID J. MALAN: All right. So what do we have inside of here? COLTON OGDEN: OK. So we have, in here, a lot
of the parts you were just talking about in your lecture. We have a CPU with its heat
sink here, right in the middle. DAVID J. MALAN: That’s a huge heat sink. And that does what? COLTON OGDEN: It dissipates heat. A CPU is very hot. It’s oscillating very fast. And so the purpose of this is to,
with all of these planes, disperse the heat equally and then get
rid of it alongside the fan as well, which acts in tandem with it. DAVID J. MALAN: Yeah. It’s a big fan, like you
would have in the summertime. COLTON OGDEN: Oh, yeah. Definitely. DAVID J. MALAN: All right. And what about these green sticks? COLTON OGDEN: These green sticks,
we only have one in this laptop. But this is actually a stick
of RAM, so random access memory where computers’ programs
are stored as they’re loaded. DAVID J. MALAN: OK. And that’s connected to this
bigger green sheet, which is– COLTON OGDEN: This bigger
green sheet is the motherboard. It’s sort of like the
central hub for all the parts working together with the computer. It acts as sort of a messaging
interface for everything. DAVID J. MALAN: OK. And now, doctor, can I take
a look at that piece of RAM? Do you need it? COLTON OGDEN: Absolutely. No. Let’s take it out of here. DAVID J. MALAN: All right. So that just snaps right out. COLTON OGDEN: Snaps right out. DAVID J. MALAN: Ah. So it looks pretty much like
the image we had earlier with a bunch of black
chips here, each of which store some number of megabytes
or gigabytes probably. And then the little gold pin, so
to speak, that could actually get plugged in. And they can only go a certain way. In fact, I’ve done this blindly
before where I’ve accidentally plugged it in the wrong way, only to
realize, it actually goes this way. And that’s why this little
divot here is asymmetric. COLTON OGDEN: Indeed. DAVID J. MALAN: I’m
done with this, doctor. OK. We’re not going to put that back in. And what’s this big thing
in the back of a PC? COLTON OGDEN: So this is
the Power Supply or PSU. It essentially just powers everything
up with electricity in the computer. DAVID J. MALAN: I see. And so if this is the extent
to which you’ve actually played with the inside of your
computer before– this, of course, is the power cable. And this is actually a standardized
plug that goes back into the device. You can actually use this or any number
of other cables on your own computer. COLTON OGDEN: Indeed. DAVID J. MALAN: All right. So where is my data stored
when not in RAM persistently? COLTON OGDEN: When not in RAM, you have,
here, an external Hard Drive, an HDB, or an internal hard
drive in this context. DAVID J. MALAN: OK. So this is older and bigger
probably than something like an SSD? COLTON OGDEN: Yes. Older and larger, but probably stores
less since this is an older computer. And it’s connected to the motherboard
using what’s called the SATA cable, S-A-T-A, which hooks right
into the motherboard. DAVID J. MALAN: Oh, yeah. Can we can we pull that out
without that much damage here? COLTON OGDEN: Yeah. Absolutely. So it’s a pretty small cable, it plugs
right into the motherboard there. DAVID J. MALAN: Ah. OK. So it’s got kind of a nice angled shape
so that it only goes, in it would seem, one way. All right. And actually, it looks like
a different type of cable is used for this older technology. We seem to have another
DVD or CD drive up there? COLTON OGDEN: We do. We do. We have a DVD drive. And actually it does you SATA as well. DAVID J. MALAN: Oh, Yes. COLTON OGDEN: It plugs right
in with the hard drives. DAVID J. MALAN: Oh. But it has a special power
cable that drives that. COLTON OGDEN: Yep. Exactly. DAVID J. MALAN: –just like
the hard drive does too. So actually, we have,
in advance, taken apart and 3.5 inch mechanical hard
drive that you previously had a whole bunch of screws
on it and probably previously had a whole bunch of data on it. But now that we’ve
exposed it to the air, and therefore all of the dust
particles here in the theater, probably not going to be
very reliable anymore. But what’s really cool now is that
we took off all but one of the screws so we can actually pull this off. And you can see what’s been inside your
own hard drive perhaps all this time. So this is, again, is 3
and 1/2 inches across, which is a standard size, at least, for
these older larger mechanical drives. There’s also a 2.5 inch version
of this commonly found in laptops or even higher-end desktops these days. And there’s that mechanical arm
that won’t move now because there’s no power going into this. But if there were, we’d be plugging
it in to the back of the device here and then that SATA cable,
which actually runs the power. And how many– it looks like
there’s two platters here. Two platters. So the data store probably
on the top, on the bottom, and then on the other
top, and the other bottom, thereby fitting even more data in here. And if this were an even
newer bigger hard drive, we could probably fit even more
platters, and therefore more data. And increasingly, is the data being
stored closer and closer together, so all those magnetic particles
are packed ever more densely, which also means we can
store more bits and thus bytes and thus files and programs. All right. So what we also have here a motherboard. Can we take a closer look
at this outside of the box? COLTON OGDEN: Yes. DAVID J. MALAN: So this one
looks a little bit different. And, in fact, I don’t see a CPU. Where’s our CPU gone? COLTON OGDEN: Well, this
one does not have a CPU. It’s been taken out in advance. But most of the other components
are still in place here. We have RAM, we have a heat sink,
and we have a lot of other ports and such that we’ve seen on the
other motherboard and was looking. DAVID J. MALAN: And these internal
ports, what gets plugged into those? COLTON OGDEN: So these are PCI slots. You’ll see oftentimes
graphics cards, sound cards– other things that aren’t
necessarily always with a computer, but are optional– those get
plugged into these ports here. DAVID J. MALAN: And it looks like if we
plug this into the back of a computer just right, these things should stick
out the back of the plastic case? COLTON OGDEN: Yes. These are ports that
are often user-facing, so you can plug-in peripherals
such as keyboards, mice, monitors with VGA ports, maybe
headphones or speakers with these ports here, headphones, microphones line
out, and a few other ports, maybe– DAVID J. MALAN: Do you want to talk
to them in some of these older ports? These are really from my day. So the parallel port,
which is where we used to put our printers or serial ports– I don’t know what voice that
is– but our serial ports where we used to put our joysticks for playing
the games, a VGA port, of course, and then a whole bunch of USB
ports there, which we can actually take a closer look at a cable. So here’s a common end of a USB cable. This is Type A, and so that’s
probably the most common type. But the white plastic on the inside
suggests that this is an older cable. If you look at newer
cables, you’ll actually see that the inside is blue, which
means its USB 3.0, which generally means faster, which means you can
move data back and forth all the more quickly. But on the other ends
of these USB cables– you see, like the Type
B connector here– this is commonly found in the
back of a printer or a scanner. So it’s a slightly different plug. It keeps one end
straight from the other. But you will actually see
sometimes smaller cables like this one here, mini
or micro USB, commonly found on phones or just
smaller devices where it would be annoying to try to
plug-in something as big as this. Well, I think we have just a
couple of other things here. Here we have– this
came from a computer. No CPU attached, but this
is one of those heat sinks? You were talking about? COLTON OGDEN: It is. It’s a combo of a heat
sink and a fan for a CPU. DAVID J. MALAN: I see. So Intel Inside might also mean you
have an Intel fan, it would seem, and heat sink. And then lastly, we’ve got
one of these things here. What’s this here? COLTON OGDEN: This is a
solid state hard drive, which actually uses flash memory very
akin to microSDs, if you’re familiar. It’s essentially what a hard drive is. But instead of having a
movable mechanical arm that looks at the different bits on
the platters, as we talked about, it’s almost like RAM. It’s just storing the
data in electricity, hence solid state, no moving parts. DAVID J. MALAN: But permanently. COLTON OGDEN: But yes. It’s nonvolatile, which
means, unlike RAM, you can actually store this whether or not
you turn your laptop off or whatever. DAVID J. MALAN: All right. And it looks like–
and I’m told I’ve got to be extra careful with this–
this is a 4 terabyte SSD. So this is a huge amount
of data, 4 trillion bytes. So we’re just going to
put this safely over here. Less expensively, though, we
have this little USB stick. It’s still 128 gigabytes,
but it’s a little gimmicky. But this thing slides
out here, and then you can plug it into your laptop or
desktop or really any device. And it’s a really
convenient way, ultimately, just like moving files back
and forth between each other. All right. Well, Dr. Ogden, thank you so much. I’m sure you’re going to want to take
care of putting this all back together. And this was hardware.

Danny Hutson

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