AP Comp Sci Sem 1 Final Flashcards by Arushi Kshatriya

Computer Science

the study of information and information processes

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binary numbers

study it

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list the binary numbers in order from least to greatest

1 2 4 8 16 32 64 128

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What is the value of the binary number 1111 1111?

255; not 256

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computing innovation

a novel or improved idea, device, product, or the development that includes a computer and/or program code as an integral part of its functionality

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information

Details, Facts, Figures, Statistics…
Sounds, Expressions, Smells…
Text, Images, Video, Audio…

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What is the big idea with binary numbers?

All digital information can be represented with just 0’s and 1’s

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demo devices

A lot if information is shared between computers - images, videos, emails, passwords, etc.
Instead of a new system for each piece of information, they can do so using a very basic system.

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What number do computer scientists start counting at

0; not 1

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Flippy Do

The paper device used for beginner computer scientists trying to learn binary

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bit

A contraction of “Binary Digit”; the single unit of information in a computer, typically represented as a 0 or 1

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byte

8 bits

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nibble

4 bits

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decimal number

a base 10 number with ten possible different digits

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How many numbers can be represented with two binary bits?

3 numbers; 01, 10, 11

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representing decimals in binary

used with a decimal point; 1000.0110; exponents are negative; some numbers, like 0.39 can’t be represented

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overflow error

Error from attempting to represent a number that is too large

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Round-off Error

Error from attempting to represent a number that is too precise. The value is rounded

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abstraction

text -> ASCII -> binary

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ASCII

the most common character encoding format for text data in computers and on the internet

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analog data

Data with values that change continuously, or smoothly, over time. Some examples of analog data include music, colors of a painting, or position of a sprinter during a race.

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Digital Data

Data that changes discreetly through a finite set of possible values

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sampling

A process for creating a digital representation of analog data by measuring the analog data at regular intervals called samples.

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hexadecimal

Hexadecimal is a numbering system with base 16. It can be used to represent large numbers with fewer digits. In this system there are 16 symbols or possible digit values from 0 to 9, followed by six alphabetic characters – A, B, C, D, E and F

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meta data

data that describes other data

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abstraction layers in color images

digital image layer -> sample layer -> pixel layer -> binary layer

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lossless compression

A process for reducing the number of bits needed to represent something without losing any information. This process is reversible.

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lossy compression

A process for reducing the number of bits needed to represent something in which some information is lost or thrown away. This process is not reversible.

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computing device

a machine that can run a program, including computers, tablets, servers, routers, and smart sensors

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computing system

a group of computing devices and programs working together for a common purpose

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computing network

a group of interconnected computing devices capable of sending or receiving data.

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path

the series of connections between computing devices on a network starting with a sender and ending with a receiver.

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bandwidth

the maximum amount of data that can be sent in a fixed amount of time, usually measured in bits per second

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protocol

An agreed-upon set of rules that specify the behavior of some system

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Internet Protocol (IP)

a protocol for sending data across the Internet that assigns unique numbers (IP addresses) to each connected device

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IP Address

The unique number assigned to each device on the Internet

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router

A type of computer that forwards data across a network

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redundancy

the inclusion of extra components so that a system can continue to work even if individual components fail, for example by having more than one path between any two connected devices in a network

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fault tolerant

Can continue to function even in the event of individual component failures. This is important because elements of complex systems like a computer network fail at unexpected times, often in groups

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User Datagram Protocol (UDP)

A protocol for sending packets quickly with minimal error-checking and no resending of dropped packets

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Transmission Control Protocol (TCP)

A protocol for sending packets that does error-checking to ensure all packets are received and properly ordered

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datastream

Information passed through the internet in packets

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packet

A chunk of data sent over a network. Larger messages are divided into packets that may arrive at the destination in order, out-of-order, or not at all

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packet metadata

Data added to packets to help route them through the network and reassemble the original message

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scalability

the capacity for the system to change in size and scale to meet new demands

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The Domain Name System (DNS)

the system responsible for translating domain names like example.com into IP addresses

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World Wide Web

a system of linked pages, programs, and files

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Hypertext Transfer Protocol (HTTP)

a protocol for computers to request and share the pages that make up the world wide web on the Internet

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digital divide

differing access to computing devices and the Internet, based on socioeconomic, geographic, or demographic characteristics.
Can affect both individual and groups.
Raises ethical concerns of equity, access, and influence globally and locally.
Affected by the actions of individuals, organizations, and governments.

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net neutrality

the principle that internet service providers should enable access to all content and applications regardless of the source, and without favoring or blocking particular products or websites.

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internet censorship

the legal control or suppression of what can be accessed, published, or viewed on the Internet

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user interface

the inputs and outputs that allow a user to interact with a piece of software. User interfaces can include a variety of forms such as buttons, menus, images, text, and graphics

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input

data that are sent to a computer for processing by a program. Can come in a variety of forms, such as tactile interaction, audio, visuals, or text

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output

any data that are sent from a program to a device. Can come in a variety of forms, such as tactile interaction, audio, visuals, or text

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sequential programming

program statements run in order, from top to bottom.

No user interaction
Code runs the same way every time

event-driven programming

some program statements run when triggered by an event, like a mouse click or a key press

Programs run differently each time depending on user interactions

debugging strategies

keep your code clean, run your code frequently, use classmates and resources

documentation

a written description of how a command or piece of code works or was developed

comment

form of program documentation written into the program to be read by people and which do not affect how a program runs

iteration

a sequence of instructions that is continually repeated

IDE

An integrated development environment (IDE) is a software application that helps programmers develop software code efficiently

API

application programming interface; a way for two or more computer programs to communicate with each other

expression

a combination of operators and values that evaluates to a single value

variable

a reference to a value or expression that can be used repeatedly throughout a program; holds one value at a time

assignment operator

allows a program to change the value represented by a variable

boolean value

a data type that is either true or false

comparison operators

<, >, <=, >=, ==, != indicate a Boolean expression

boolean expression

evaluates to either true or false

function

a named group of programming instructions. Also referred to as a “procedure”

function call

a command that executes the code within a function

global variable

Permanent. Can be used anywhere in your code.

local variable

Temporary. Can be used only in the part of the code where it was created, like inside an onEvent(). Deleted once the onEvent() is done running.

transversals

A way to travel through all the elements of a list.
We will use for loops to do this.

intellectual property

a work or invention that is the result of creativity, such as a manuscript or a design, to which one has rights and for which one may apply for a patent, copyright, trademark, etc.

abstraction

the process of removing elements of a code or program that aren’t relevant or that distract from more important elements

high vs. low level programming languages

A high-level language is one that is user-oriented in that it has been designed to make it straightforward for a programmer to convert an algorithm into program code. A low-level language is machine-oriented. Low-level programs are expressed in terms of the machine operations that must be performed to carry out a task.

parameter

subvalue within a line of code
example: function addNumber ( x , y ) -> x and y would be the parameters

concetanate

the operation of joining two strings together

HyperText Markup Language

HTML; the standard markup language for documents designed to be displayed in a web browser

speedup

sequential time divided by parallel time
the time used to complete a task sequentially divided by the time to complete a task in parallel

sequential computing

programs run in order, one command at a time

Parallel Computing

programs are broken into small pieces, some of which are run simultaneously

Distributed Computing

programs are run by multiple devices

Library

a group of functions (procedures) that may be used in creating new programs

API

Application Program Interface - specifications for how functions in a library behave and can be used - The documentation for each function in the library

Procedural Abstraction

provides a name for a process and allows the procedure (function) to be used only knowing what it does, and not necessarily how it does it

Modularity

the subdivision of a computer program into separate subprograms

Two distinctions with data

What does the data show - fact
Why might this be the case - opinion

correlation

similarities, patterns

causation

this thing caused that thing

metadata

Data about other data
Can Help us uncover the why
questions. (sometimes auto gathered)

Metadata are data about data:

It can be changed without impacting the primary data
Used for finding, organizing, and managing information
Increases effective use of data by providing extra information
Allows data to be structured and organized

visualizations

Look at lots of data at once
See patterns that are “invisible” if you just look at the table

data analysis process

collect or choose data
clean and/or filter
visualize and find patterns
generate new information

bar chart

Count how many times each value in the column appears and make a bar at that height.
What value(s) are most common in this column?
What value(s) are least common in this column?
What is the unique list of values in this column?

histogram

Similar to a bar chart, but first all numbers in a range or “bucket” are grouped together. For example, the chart below has a bucket size of 20 so the numbers 41, 48, and 53 would all be placed in the same bucket between 40 and 60.

Histograms can only be created with numeric data but can be useful when a normal bar chart may be difficult to read.
What range of value(s) are most common in this column?
What range value(s) are least common in this column?
What ranges of values do or do not appear in this column?

visualization takeaways

Programs (like the Data Visualizer) can help process data so we can understand it and learn.

Charts and other visualizations can help both find and communicate what we’ve learned from data

Bar charts and histograms are two common chart types for exploring one column of data in a table.

when does data need to be cleaned?

Data is incomplete
Data is invalid
Multiple tables are combined into one

What leads to “messy” data?

Users enter in different types of data (“two”, 2)
Users use different abbreviations to represent the same information (“February”, “Feb”, “Febr”)
Data may have different spellings (“color”, “colour”) or inconsistent capitalization (“spring”, “Spring”)

cleaning data

Look through the data manually. Find and fix messy data.
Use a program to find and fix messy data.

filtering data

Filtering data allows the user to look at a subset of the data.
In Unit 5, we filtered data programmatically using traversals to gain insight into knowledge from data.
Software programs with built in tools (like the Data Visualizer) can also be used to filter data.

data stored in text files

old school PC games
.csv Comma Separated Values
date, level, score
01/11/2019, 9. 73
Common File Format
Require Spreadsheet Programs or Specific Programs to Iterate Through

Easy to mess up a file
No Standard ways to create file

data storage through spreadsheets

Designed for people to analyze data not for programs

data storage through databases

Preferred method of storing data that will be used in programs

Programers use SQL (Structured Query Language) to interact with databases.

To be a Data Scientist You often need to learn programming languages like Python/R to analyze and visualize data.

You also need to learn SQL to be able to interact with databases

scatter plot

counts how many times combinations of values appear. Arrows show where that row in the data table would be counted in the chart
Counts how often pairs of values in two columns appear.

Useful for:
Finding the most / least common combinations of values in two columns
Finding patterns across two columns
Exploring two columns when one or both are strings.

Not useful:
If either column has too many values (the chart would be enormous)

crosstab chart

Useful for:
Finding the most / least common combinations of values in two columns
Finding patterns across two columns
Exploring two columns when one or both are strings.

Not useful:
If either column has too many values (the chart would be enormous)

when to use what graph

study slide 17 in 9.4

big data

“collecting data from others so you can analyze it”
Crowdsourcing is the practice of obtaining input or information from a large number of people via the Internet.
Citizen science is research where some of the data collection is done by members of the public using own computing devices which leads to solving scientific problems
Crowdsourcing offers new models for collaboration, such as connecting businesses or social causes with funding
Both are examples of how human capabilities can be enhanced by collaboration via computing

citizen science and crowdsourcing

open data

“sharing data with others so they can can analyze it”
Open data is publicly available data shared by governments, organizations, and others
Making data open help spread useful knowledge or creates opportunities for others to use it to solve problems

Computing Innovation

includes a program as an integral part of its function. Can be physical (e.g. self-driving car), non-physical computing software (e.g. picture editing software), or non-physical computing concepts (e.g., e-commerce).

Personally Identifiable Information (PII):

information about an individual that identifies, links, relates, or describes them.
Most digital technology needs some kind of PII to work
advertise to you by creating detailed profiles of who you are and what you like
PII can be used to steal the identity of a person, or stalk them online. Information that is often posted on social media can be combined to create a profile on you.

10.3 takeaways

slide 6

Phishing

a technique that attempts to trick a user into providing personal information. That personal information can then be used to access sensitive online resources, such as bank accounts and emails.

Keylogging

the use of a program to record every keystroke made by a computer user in order to gain fraudulent access to passwords and other confidential information

Malware

oftware intended to damage a computing system or to take partial control over its operation

Rogue Access Point

a wireless access point that gives unauthorized access to secure networks. (starbucks2) (airport/traveling)

10.4 takeaways

Our private data powers a lot of computing innovations in ways we like. It makes products that are convenient, interesting, personal, useful, and often “free” because we “pay” with our data.
Not every effect of a computing innovation is anticipated in advance.
This data can also be used by companies, governments, or criminals in ways that we didn’t intend or that threatens our privacy.

Encryption

a process of encoding messages to keep them secret, so only “authorized” parties can read it.

Decryption

a process that reverses encryption, taking a secret message and reproducing the original plain text.

Symmetric Key Encryption

involves one key for both encryption and decryption.

Public Key Encryption

pairs a public key for encryption and a private key for decryption. The sender does not need the receiver’s private key to encrypt a message, but the receiver’s private key is required to decrypt the message.

Multifactor Authentication

a method of computer access in which a user has to successfully provide evidence in at least two of the following categories: knowledge (something they know), possession (something they have), and inherence (something they are). Each step provides a new layer of security.

Computer Virus Scanning Software

protects a computing system against infection.

Cipher

the generic term for a technique (or algorithm) that performs encryption

Caesar’s Cipher:

a technique for encryption that shifts the alphabet by some number of characters.

Cracking encryption

When you attempt to decode a secret message without knowing all the specifics of the cipher, you are trying to crack the encryption.

asymmetric key encryption

allows users to encrypt information using shared keys

Distributed Denial of Service (DDos)

a cybercrime in which the attacker floods a server with internet traffic to prevent users from accessing connected online services and sites

digital certificate

an electronic document used to prove the validity of a public key

random substitution cipher

an encryption technique that maps each letter of the alphabet to a randomly chosen other letters of the alphabet.

big data

data that contains greater variety, arriving in increasing volumes and with more velocity

digital divide

the gap between demographics and regions that have access to modern information and communications technology (ICT), and those that don’t or have restricted access

heuristic

when it’s impractical to solve a particular problem with a step-by-step algorithm

botnet

a network of computers infected by malware that are under the control of a single attacking party, known as the “bot-herder

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AP Comp Sci Sem 1 Final Flashcards

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