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Файл:IT English through Short Films. Учебное пособие по английскому языку
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digitized by taking “snapshots” of their amplitudes every few
milliseconds. These are recorded as numbers in the form of binary
strings, with as many as 44,000 for every second of sound. When
they’re read by your computer’s audio software, the numbers determine
how quickly the coils in your speakers should vibrate to create sounds of
different frequencies. All of this requires billions and billions of bits.
But that amount can be reduced through clever compression formats.
For example, if a picture has 30 adjacent pixels of green space, they can
be recorded as “30 green” instead of coding each pixel separately – a
process known as run-length encoding. These compressed formats are
themselves written in binary code.
So is binary the end-all-be-all of computing? –Not necessarily. There’s
been research into ternary computers, with circuits in three possible
states, and even quantum computers, whose circuits can be in multiple
states simultaneously. But so far, none of these has provided as much
physical stability for data storage and transmission. So for now,
everything you see, hear and read through your screen comes to you as
the result of simple “true” or “false” choice, made billions of times over.
5. HOW COMPUTERS WORK: CPU, MEMORY, INPUT
https://www.youtube.com/watch?v=DKGZlaPlVLY&t=8s
- Hi, my name is Madison Maxey. I have a company called Loomia, and
we focus on making smart fabrics for smart clothing and smart soft good
products. The sky’s the limit when it comes to textiles.
- My name is Danielle Applestone, and I’m CEO of Othermachine
Company. We build a desktop milling machine. A milling machine
takes a rotating cutting tool and moves it through material to create a 3D
object.
Madison: Under the hood, all computers do the same four basic things.
They input information, store and process the information, and then,
output information. Each of these things is done by a different part of
the computer. There input devices that take input from the outside world
and convert it into binary information. There is memory to store this
information. There’s a central processing unit or CPU, where all the
calculations are done. And, finally, there are output devices that take
information and convert it into a physical output. Let’s talk about input
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first. Computers can take many different types of input, like the
keyboard of a computer, the touchpad of a phone, a camera, a
microphone, or a GPS. But even the sensors on a car, a thermostat, or a
drone are also different input devices.
Danielle: Now, let’s look at a simple example of how input travels
through a computer and becomes output. When you press a key on your
keyboard-let’s say the letter “B”. The keyboard converts the letter to a
number. That number is sent as binary, ones and zeros, into the
computer. Starting from this number, the CPU calculates how to display
the letter “B” pixel by pixel. The CPU requests step-by-step instructions
from memory, which tell it how to draw the letter “B”. The CPU runs
these instructions and stores the results as pixels in memory. Finally,
this pixel information is sent in binary to the screen. The screen is an
output device, which converts the binary signals into the tiny lights and
colors that make up what you see.
Madison: This all happens so quickly it feels instantaneous, but to
display each letter a computer runs thousands of instructions, starting
from the moment your finger presses the key point.
Danielle: In that example, the output device was the screen, but there are
many different types of output which take a binary signal from the
computer and do something in the physical world. For example, a
speaker will play sound, and a 3D printer will print an object. Output
devices can also control physical motion like a robotic arm, the motor of
a car, or the cutting tool of the milling machine that my company
makes. New types of inputs and outputs let computers interact with the
world in entirely new ways. This has been helped out by improvements
to the speed and size of the memory and CPU. The more complicated a
task is and the more information that is input or output, the more
processing power and memory a computer needs. Typing letters on a
screen may be easy but to do complicated 3D graphics or record a highdefinition movie, modern computers often have multiple CPUs to
process all that information and many gigabytes of memory to store it.
Madison: No matter what it is you want to do with the computer, every
single action is about: inputting information from the physical world,
storing and processing that information, and getting some output back
into the physical world.
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6. HOW COMPUTERS WORK: HARDWARE AND SOFTWARE
https://www.youtube.com/watch?v=xnyFYiK2rSY
- Hi, my name is Erica Gomez and I’m an engineering manager at
Amazon.com. One of the best things about working in tech, and at
Amazon in particular, is that I get to bring my dog with me to work
every day. My job is to help make sure software gets out the door and
her job is to nap under my desk and snore very loudly.
- My name is Jerome Holman, and I’m a Program Manager on Team
Xbox and I have a really fun job: Basically bringing the hardware and
the software together to give you all the games that you love on your
Xbox.
Erica: When you look inside a computing device you see a bunch of
circuits, chips, wires, speakers, plugs, and all sort of other stuff. This is
the hardware. But what you don’t see is the software. Software is all of
the computer programs, or code, running on this machine. Software can
be anything from apps and games to webpages and the data science
software that me and my teams use at Amazon to understand how
customers behave. But how do the hardware and the software interact
with one another? Let’s start at looking at a computer’s central
processing unit, or CPU.
Jerome: The CPU is the master chip that controls all the other parts of
the computer. A CPU needs to do different things so inside it has
smaller, simpler parts that handle specific tasks. It has circuits to do
simple math and logic. It has other circuits to send and receive
information to and from different parts of the computer. The real magic
of the CPU is how it knows which circuits to use and when to use them.
Erica: The CPU receives simple command that tell it which circuit to
use to do a specific job. For example, an “add” command tells the CPU
to use its outer circuit to calculate a new number. And then the “store”
command tells the CPU to use a different circuit to save that result into
memory. Just like numbers, all of these simple commands can be
represented in binary ones and zeros or on and off electrical signals. The
binary commands are stored in memory and the CPU fetches and
executes them in sequence one after the other. The sequence of
commands is , in fact, a very simple computer program.
Jerome: Binary code is the most basic form of software and it controls
all the hardware of a computer. These days, nobody writes software in
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binary. It would take forever! Today, the software we write looks more
like this (pause) or this or even this (the examples are given).
Programming languages like these let you type in commands in
something that looks a lot like English. To draw a rectangle on the
screen, you just need a single command. This high-level command is
converted into hundreds, or thousands, of simpler binary commands that
the CPU understands.
Erica: Software tells the CPU what to do, but when you’re listening to
music, and browsing the web, and chatting with a friend, your computer
is running multiple pieces of software all at once. So, how do all of
these programs get on the computer in the first place, and how can the
CPU run them all at once? To find out we’ll have to take a look at the
operating system.
Bill Gates: The operating system of the computer is the master program
that manages how software gets to use the hardware of the computer.
For example, I helped create the Windows operating system that runs on
most personal computers. The operating system is a program with
special abilities that let it control the other software on the computer. It
lets you install new programs by loading them into your computer’s
memory. It decides when a program is run by the central processing
unit, and whether that program can access the computer’s input and
output devices. And when you think your computer is running many
programs at once, in reality, it’s the operating system that’s quickly
switching between programs sharing that CPU for fractions of a second.
Erica: Inside every computer is an operating system managing software
that controls the computer’s hardware. The software is a series of
commands made of simple binary code, and that binary code is just
electrical signals flowing through billions of tiny circuits.
Bill: Computers have the potential to do all kinds of amazing things. But
the only thing that makes the computer smart, or useful, is you. When
you learn to code you get to define the problem you want to solve, and
write the software that turns those ideas into reality. That gives you the
power to build things that matter to you, your community, and the
world.
7. CPU CACHE EXPLAINED
https://www.youtube.com/watch?v=yi0FhRqDJfo
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What is CPU cache? Now a computer has two different types of
memory. One type is what is used in RAM modules, which is DRAM or
a dynamic RAM. And DRAM is memory that uses capacitors to store
data and these capacitors have to be constantly and dynamically
refreshed often with electricity in order for them to store data. But
there’s another type of memory that a computer uses that doesn’t have
to be constantly refreshed. And this memory is called SRAM or static
RAM. And SRAM is what is used in the CPU cache. And because
SRAM doesn’t have to be constantly refreshed, it’s a lot faster than
DRAM and it’s also very expensive.
The CPU cache is the CPU’s internal memory. And its job is to store
copies of data and instructions from RAM that’s waiting to be used by
the CPU. So basically what the CPU cache does, is that it holds
common data that it thinks the CPU is going to access over and over
again. Because when the CPU needs to access certain data, it always
checks the faster cache memory first to see if data it needs is there. And
if it’s not, then the CPU would have to go back to the slower primary
memory or RAM to get the data it needs. So that’s why cache memory
is so important. Because if the CPU can access what it needs on the
faster cache, the faster the computer will perform. So basically the
whole idea behind cache is to make the computer run faster at a cheaper
price.
Now a computer can run without the CPU cache but it would be a lot
slower. Even though RAM is becoming faster, it still can’t feed the data
to the CPU fast enough. Because CPUs have gotten so fast, that a lot of
times the CPU is waiting around doing nothing while it waits for more
data, and it creates a bottleneck. So that’s why the CPU cache was
developed. It can act like a middleman between the CPU and RAM to
assist in feeding the CPU that data it needs a lot faster, which reduces
bottlenecks.
CPU cache comes in three different levels. For example, there’s level 1
cache, which is also called primary cache, and level 1 cache is located
on the processor itself. So it runs at the same speed as the processor. So
it’s very fast and is the fastest cache on the computer. And there is also
level 2 cache, which is also called external cache. Level 2 cache is used
to catch recent data accesses from the processor that were not caught by
the level 1 cache. So in a nutshell, if the CPU can’t find that data it
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needs in the level 1 cache, it then searches the level 2 cache for the data.
And if the CPU can’t find the data in the level 2 cache, then it searches
the last level of cache, which is level 3. And the level 3 cache is used to
catch recent data accesses that were not caught by the level 2 cache.
And finally, if level 3 doesn’t have the data, the CPU has to go back to
the slower RAM to find the data it needs.
In earlier computers the level 2 cache was located on a separate chip on
the motherboard. Or in modern CPUs it would be located on the
processor. Level 2 cache is larger than level 1 cache but it’s not as fast
as level 1 cache. And level 3 cache is also located on the processor.
Level 3 is larger than level 2 but it’s not as fast as level 2 cache. Level 3
is often referred to as shared cache because its memory is shared
between all the cores on the CPU, whereas level 1 and level 2 cache are
dedicated to their own CPU core.
8. CIRCUITS AND LOGIC
https://www.youtube.com/watch?v=ZoqMiFKspAA
Limor: One of the coolest things I’ve discovered about circuits is
circuitry can be an art form like if I have a creative idea, I can get that
creative idea out using circuits. So if you have ideas, you can use
technology to make those ideas come to life. Every input or output of a
computer is effectively a type of information, which can be represented
by on or off electrical signals or ones and zeros. In order to process the
information that comes in as input, and to make the information that is
output, a computer needs to modify and combine the input signals. To
do this, a computer uses millions of teeny electronic components, which
come together to form circuits.
Nat: Let’s take a closer look at how circuits can modify and process
information that’s represented in ones and zeros.
A simple circuit
This is an incredibly simple circuit. It takes an electrical signal, on or
off, and it flips it. So if the signal you give it is a 1, the circuit gives you
a 0, and if you give the circuit a 0, it gives you a 1. The signal that goes
in is not the same as the signal that comes out, and so we call this circuit
NOT.
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Limor: More complicated circuits can take multiple signals and combine
them, and give you a different result. In this example, a circuit will take
two electrical signals, now each one might be a 1 or a 0. If either of the
signals coming in is a 0, then the result is also a 0. This circuit will only
give you a 1, if the first signal and the second signal are both a 1, and so
we call the circuit AND. There are many small circuits like this that
perform simple logical calculations. By connecting these circuits
together, we can make more complex circuits that perform more
complex calculations. For example, you can make a circuit that adds 2
bits together called an ADDER. This circuit takes in 2 individual bits,
each one a 1 or a 0, and adds them together to calculate the sum. The
sum can be 0 plus 0 equals 0, 0 plus 1 equals 1, or 1 plus 1 equals 2.
You need two wires coming out because it can take up to two binary
digits to represent the sum. Once you have a single adder for adding two
bits of information, you can put together multiples of these adder
circuits side-by-side to add together much larger numbers.
Nat: For example, here’s how an 8-bit adder adds the numbers 25 and
50. Each number is represented using 8 bits, resulting in 16 different
electrical signals that go into the circuit. The circuit for an 8-bit adder
has lots of little adders inside of it, which together, calculate the sum.
Different electrical circuits can perform other simple calculations like
subtraction or multiplication. In fact, all the information processing your
computer does is just lots and lots of small simple operations put
together. Each individual operation done by a computer is so, so simple
it could be done by a human, but these circuits inside computers are way
way faster.
Limor: Back in the day, these circuits were big and clunky, and an 8-bit
adder could be as big as a fridge, and it
would take minutes for them to perform a simple calculation. Today,
computer circuits are microscopic in size, and way way faster. Why are
smaller computers also faster?
Nat: Well, because the smaller the circuit is, the less distance the
electrical signal has to go. Electricity moves at just about the speed of
light, which is why modern circuits can perform billions of calculations
per second.
Limor: So whether you’re playing a game, recording a video, or
exploring the cosmos, everything you could possibly do with technology
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requires lots of information to be processed extremely quickly.
Underneath all this complexity is just lots of teeny little circuits that turn
binary signals into websites, videos, music, and games. These circuits
can even help us decode DNA to diagnose and cure disease. So what
would you like to do with all these circuits?
9. LINUX EXPLAINED: WHAT IS THE LINUX KERNEL
https://www.youtube.com/watch?v=pJ607nDnyE0
In this video we answer the question “Is Linux an operating system?”
There has been a great deal of confusion about the word Linux because
of how it is used popularly versus how it is used technically. Let’s look
at it from both angles.
Technically Linux is actually not an operating system. An OS is system
software that does 2 things. It manages computer hardware and
Software resources. And it provides common services for computer
programs. Almost all computer programs require an operating system to
function. There are several components of an OS that together make the
different parts of a computer work. One of these key components is
called the kernel. That’s where Linux comes in.
Linux is a kernel. A kernel is the core program of an operating system.
It’s the first program loaded on startup and it mainly does three things.
It handles the rest of the startup process. It handles the input/output
requests from other programs. It manages memory and hardware
peripherals like keyboards, monitors, printers, speakers and etc.
Linux is the most widely used free and open-source kernel on the planet.
Android Google’s mobile operating system uses a modified version of
the Linux kernel. And many if not most internet servers also use the
Linux kernel. It is a very versatile piece of software that helps power
millions of devices every day.
Now let’s look at it from the popular angle. What happened was in the
early to mid-90s shortly after the creation and release of the Linux
kernel in 1991, many developers began combining the Linux kernel
with a free and open-source operating system called GNU replacing the
kernel that GNU was currently using. They did this because of the
functionality and benefits that Linux was currently offering its users that
GNU kernel at the time was lacking. The popularity of this new
operating system combination grew exponentially over the next couple
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of years. However, there also grew a controversy among the free
software community about what to call operating systems that were
using this combination of the new software and the Linux kernel. The
controversy continues to this day. The general public mainly refers to
this combination of software as Linux whereas more technical users
refer to it as GNU Linux or GNU plus Linux. Fortunately, the benefits
that GNU and the Linux kernel provide today are available to any user
in the form of distributions. Ubuntu, Linux Mint and Fedora are
examples of such distributions.
10. COMPUTER BASICS: UNDERSTANDING APPLICATIONS
https://www.youtube.com/watch?v=3gMOYZoMtEs
If you woke up this morning thanks to the alarm on your smartphone or
if you like watching videos or playing games on your tablet, you’re
using applications, also known as apps.
An app is a software program that lets you do things (for lack of a better
word). You’ll find apps on all of your devices including smartphones,
tablets and computers. Some apps help you complete tasks while others
are just for fun.
There are some examples of ways you can use apps. Mobile apps are
apps that run on your smartphone or tablet. They can make many things
in life more convenient. For instance, if you are looking for a place to
buy coffee, an app like Google maps can determine your current
location and then recommend nearby coffee shops.
Apps are not just for mobile devices though. The programs and
applications on your computer can also be considered apps. If you’ve
ever used Microsoft Word to create a document or a web browser to
visit a website or check your email, guess what, you have used an app.
Some apps come already installed but you can easily download or buy
more online. Apps are about communication, productivity,
entertainment and more. With so many possibilities you are sure to find
several apps that are perfect for the things you do.
11. HOME NETWORKING – HOW TO HOOK IT ALL UP
https://www.youtube.com/watch?v=-L1eI4vECo4
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An IP address / Internet Protocol address is given to each and every
computer on a network. It doesn’t matter if that’s your home network or
your internet service provider or ISP’s network that you pay to be a part
of it gets an IP address. The IP address is the identity of your computer
on the network and without it devices won’t know where to send their
data. I like to use the analogy of snail mail. Each house on a street will
need its own address or the mailman won’t know where to deliver your
bills.
The most basic ways to connect to a network would be to pay an ISP for
access to their network and with it access to the Internet. You can’t get
free Internet unless you steal your neighbor’s Wi-Fi and I don’t really
recommend that. You’ll need to pay an ISP for access. If you’re on a
tight budget call them up and ask about any cheap plans they have. Lots
of times they will have plans they don’t advertise.
So they’ll send you a modem to lease or you can purchase your own.
What’s a modem -you ask. A simple way to think of a modem is we’ll
convert the signal coming from your ISP into something the PC can
understand. In this instance let’s go with cable internet service. That’s
what I have and I can easily show that. Hooking it up is easy: screw on
the cable line to the modem and then an Ethernet cable into the back of
the modem and then the other side to your laptop. This is the most basic
setup even though it is neither ideal nor recommended. Later your
laptop will be assigned an IP address by the ISP and it will now have an
internet connection through the Ethernet cable.
What if you have more than one computer or device? You could add a
switch. A switch will allow you to add more ports to a network. To hook
up everything this way you’d plug in the Ethernet cable into the modem
and then the other end to the switch. Now run an Ethernet cable from a
port on the switch to any of your devices. Now your devices are
connected to the network through the switch. You should be able to
share files and other things and share the internet connection, but as I
mentioned, this setup is not ideal. Each of these devices will need their
own IP address and your ISP may not give you so many. Some may
only give you one or two, maybe three. When you exceed this number
whatever it is, those additional devices will not get an IP address and
won’t be able to communicate on the network. Also, all of these devices
will be exposed on the public Internet, which is a large security risk.
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