Khan Academy - Computers

Erica is trying to describe how a computer works to her 7-year-old cousin, by relating each part to how humans work. Fill in the words that make the most sense for this metaphor: "Let's think of a computer like a person. Just like we have 5 senses to take in the world around us, a computer has to take in data from the human world, like a . We use our brains to process that data, but a computer uses a . We display our reactions using our voice or bodies, whereas a computer shows results using an , like a .

"Let's think of a computer like a person. Just like we have 5 senses to take in the world around us, a computer has INPUT DEVICES to take in data from the human world, like a MICROPHONE. We use our brains to process that data, but a computer uses a CPU. We display our reactions using our voice or bodies, whereas a computer shows results using an OUTPUT DEVICE, like a SPEAKER

Zariyah is storing files on her computer for a school research project on swing dancing. Which of these lists correctly sorts the files from largest size to smallest size?

"performance.mov" (1.2 GB) "winners.jpg" (2 MB) "history.epub" (800 KB) "howto.epub" (320 KB) "moves.csv" (240 B)

Jermaine is storing files on his laptop for a project about his family ancestry. Which of these lists correctly sorts the files from largest size to smallest size?

"reunion.mov" (15 GB) "interview.mov" (1.2 GB) "grandfather.jpg" (2 MB) "grandma_bw.jpg" (900 KB) "familytree.ged" (32 KB) "notes.txt" (450 B)

The Apple iPhone includes a settings menu where you can toggle various accessibility options on or off: What is the minimum number of bits that can represent those 2 options

2

Adrian is making a simple computer using 3 wires. Each wire can be considered either "on" or "off" depending on its voltage, thanks to the transistors. How many bits of information can those wires represent?

3

The Apple iPhone includes a settings menu where you can toggle various accessibility options on or off: What is the minimum number of bits that can represent those 3 options?

3

The diagram below shows a circuit with three gates, where the output from two AND gates are sent into an OR gate. The circuit has four inputs (A, B, C, D), two for each AND gate. If the final output is 111, what is a possible state of the inputs A/B/C/D?

A = 1, B = 1, C = 0, D = 1

The diagram below shows a circuit with four gates, where the output from two AND gates are sent into a third AND gate, and the output from that gate is sent into a NOT gate. The circuit has four inputs (A, B, C, D). If the final output is 0, what are possible states of inputs A, B, C, and D?

A = 1, B = 1, C = 1, D = 1

What values can a binary digit represent?

A binary digit can represent either the value 0 or 1.

Select the true statements about logic gates:

A logic gate is any device that implements a boolean function, outputting a single binary output.

Landyn has a smart phone that can store 1 GB of data. He sees a commercial for a new phone that promises storage for 1 TB of data. What's the best estimate of how much more data the new phone will allow him to store?

Around 1000 time more data

In the 1990s, it was common for desktop computers to come with a hard drive that could store 240 MB of data. Now, it's common for laptop computers to come with a hard drive with a capacity of 240 GB. What's the best estimate of how much more data can be stored in 240 GB versus 240 MB?

Around 1000 times more data.

The diagram below shows a circuit where an AND gate leads to an OR gate. The circuit has three inputs (A, B, C) and a single output. If the output is 111 and input C is 111, what are the possible states of inputs A and B?

Both inputs A and B are 0 Input A is 1, input B is 0 Both inputs A and B are 1 Input A is 0, input B is 1

A computer is built up with layers of components, from the lowest level components to the highest level components. Which of these lists correctly sorts components from high-level to low-level?

CPU, logic circuit, logic gate, transistor

How does a computer store numbers in memory?

Computers represent numbers in memory using the binary number system.

Marquis needs to upload a photo of himself to a website, and the website requires that photos be in JPEG format. However, his only photo is in the GIF format. Which of these approaches should he take?

He can open the file in an image editing application, export it as a JPEG, and upload the exported JPEG file.

Shir wants to know how powerful her computer is, and she finds this display of information: It says her computer has 16 GB of memory. What can her computer do with that memory amount?

Her computer can remember 16GB worth of instructions and data at any time, shared by all the open applications.

A truth table shows the output values for a logic gate, based on a set of input values. Complete this truth table for an OR gate by entering either 0 or 1 in the output column: Input A Input B Output 0 0 0 1 1 0 1 1

Input A Input B Output 0 0 0 0 1 1 1 0 1 1 1 0

A truth table shows the output values for a logic gate, based on a set of input values. Complete the truth table for an OR gate by entering either 0 or 1 in the output column: Input A Input B Output 1 1 1 0 0 1 0 0

Input A Input B Output 1 1 1 1 0 1 0 1 1 0 0 0

The following circuit takes the output of an OR gate and sends it through a NOT gate. This circuit is logically equivalent to the NOR logic gate, a common gate in computers. Fill out the truth table for the circuit by entering a 0 or 1 in the output column for each row:

Input A Input B Output 0 0 1 0 1 0 1 0 0 1 1 0

Which logic gate will invert a single value?

NOT gate

A truth table shows the output values for a logic gate based on a set of input values. Consider the following truth table: 0 0 0 0 1 1 1 0 1 1 1 1 Which logic gate has a truth table that looks like that table?

OR Gate

When we're working with logic gates, we use multiple terms to describe the input and output values. For each of the terms below, enter the corresponding binary value (0 or 1): Term Binary value "on" "off" "low" "high" "false" "true"

Term Binary value "on" 1 "off" 0 "low" 0 "high" 1 "false" 0 "true" 1

An Apple Mac computer includes a status menu with various indicators: Which of the indicators could represent a single bit of information?

The bluetooth status (disconnected/connected) The source of power (battery/adapter)

Back in 1995, the Windows 95 computer came with 4 MB of RAM (Random Access Memory). These days, most Windows computers come with at least 8 GB of RAM. That's 2000 times more RAM. What becomes possible with that increase in memory?

The computer can run more applications at once, since it can store their instructions in memory.

Which of these are examples of metadata for a photo?

The number of bytes of data in the file The people who have permission to edit the file The type of camera that took the photo The timestamp when the photo was downloaded

Digital alarm clocks display information and visual indicators to help people wake up on time: Which of the displays could be represented by a single bit?

The temperature unit indicator ("C" or "F") The "PM"/"AM" indicator

Nikolas is looking at the files for a project he's working on: Screenshot of file listing. Which file was modified the longest time ago? Which file is the largest? Which file type appears the most in this listing?

Which file was modified the longest time ago? pause.svg Which file is the largest? tests.zip Which file type appears the most in this listing? PNG

Peter wants to make a computer, but doesn't have the money to buy a CPU. He only has the money for a keyboard, RAM (Random Access Memory), and monitor. Why is the CPU important?

Without a CPU, the computer can't process the data that comes from the keyboard.

A computer is built up from layers of components. The lowest level components are responsible for tiny computations, and the highest level components are responsible for sophisticated multi-step computations. Which of these lists correctly sorts components from high-level to low-level?

computer, integrated circuit, logic gate, transistor

The diagram below shows a circuit with three gates, where the output from two OR gates are sent into a third OR gate. The circuit has four inputs (A, B, C, D), two for each OR gate. If the final output is 000, what is a possible state of the inputs A/B/C/D?

A = 0, B = 0, C = 0, D = 0

The diagram below shows a circuit with three gates, where the output from two OR gates are sent into a final AND gate. The circuit has four inputs (A, B, C, D), two for each OR gate. If the final output is 000, what is a possible state of the inputs A/B/C/D?

A = 0, B = 1, C = 0, D = 0

The diagram below shows a circuit where an AND gate leads to an OR gate. The circuit has three inputs (A, B, C) and a single output. If the output is 0 and input C is 0, what are the possible states of inputs A and B?

Both inputs A and B are 0 Input A is 0, input B is 1 Input A is 1, input B is 0

The diagram below shows an OR gate. If the output wire is off (0), what are the possible states of the input wires?

Both inputs are 0

The diagram below shows a circuit where an OR gate leads to an AND gate. The circuit has three inputs (A, B, C) and a single output. If the output is 111 and input C is 111, what are the possible states of inputs A and B?

Input A is 0, input B is 1 Both inputs A and B are 1 Input A is 1, input B is 0

The diagram below shows an AND gate. If the output wire is off (0), what are the possible states of the input wires?

Input A is 0, input B is 1 Input A is 1, input B is 0 Both inputs are 0

A computer is built up from layers of components, like an integrated circuit, logic gates, and transistors. Which of these is the best description of a transistor?

It converts an electrical signal into a 0 or 1 based on the amount of voltage going through it.

Aaliyah is looking through her computer files and discovers a file that has no extension. What is true about that file?

It is stored as binary data by the computer.

A computer is built up from layers of components, like a CPU, logic circuits, logic gates, and transistors. Which of these is the best description of a logic gate?

It outputs 0 or 1 based on input values and a Boolean function.