Computer science Paper 2 Advanced Specification Key Cards

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  • Created by: mugmaniac
  • Created on: 23-05-22 11:48
What is Base 10, Base 2 and Base 16?
Decimal (10)
Binary (2)
Hexadecimal (16)
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What base does computers usually use to represent all instructions and data?
Binary.
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Why is hexadecimal often use in computer science?
- It makes it much more easier to read, write and understand hexadecimal.
- It is very concise and by using a base of 16 it can signify a given number, with the numbers 10 - 15 replaced by letters, it can give more information this way.
- Hexadecimal can
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Convert,
01010110
to decimal.
86
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What is 25 in hexadecimal?
19
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What is the highest number you can make in binary?
255
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What is a bit?
a bit is representation of a 1 or a 0.
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What is a byte?
a group of 8 bits
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Order these quantities of bytes in order.
GB
MB
kB
TB
B
B
kB
MB
GB
TB
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Why are binary shifts are used?
Binary shifts are used to perform a simple multiplication or division such as a binary left shift of one performs a multiplication of 2, a binary shift of 2 performs a multiplication of 4.
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Add
1011010
1101011
together.
1000101
Over flow -> 1
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What is an overflow?
an over flow is when a 8 bit value exceeds its 8 bits.
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What does a one right shift do?
Divides the decimal number by 2.
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What is a character set?
A character set is a variety of binary values assigned to an character. Like ASCII and Unicode.
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What is the character Codes for A and B?
It goes in alphabetical order so, A is 65 and B is 66 and so on.
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What is similar between Unicode and ASCII?
They both uses the same codes as ASCII up to 127.
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What is the purpose of Unicode?
Unicode provides a larger range of characters and is able to be used by all languages.
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What are the advantages of Unicode over ASCII?
Unicode provides a larger variety of characters, this in return though has a larger size compared to ASCII.
Unicode is able to be used by all languages
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What is a Pixel?
a single point on an Image.
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What is pixel short for?
Picture Element.
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How are images made by pixels.
Multiple pixels make up an image, the higher the number of pixels the higher the resolution, the higher the memory usage.
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What is an Image size?
An image size is expressed directly as an width of an image in pixels by height of image in pixels, width x height.
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What is colour depth?
Colour depth is the number of bits used to represent each pixel.
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How a bitmaps used to represent images using pixels and colour depth?
Bitmaps give a visual representation of how binary code puts together pictures, usually compromised of boxes and such.
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How does the number of pixels and colour depth affect he file size of a bitmap?
The more pixels and colours that a bitmap can use the higher the file size of it.
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How do you calculate image bitmap file sizes?
Size = Width x Height x Depth
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Is sound analogue or digital?
Analogue
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Why does sound needs to be converted into a digital form and processing in a computer?
Sound is in analogue, a computer can only read in machine code so in order to do so sound is sampled into a digital format comprised of machine code.
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What is a sample?
A sample is a measure of amplitude at a point in time.
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What is a sample rate?
Sample rate is the number of samples take in a second measured in hertz.
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What is a sample resolution?
Sample resolution is the number of bits per sample.
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how do you calculate sound file sizes based on the sampling?
File size in bits = rate x res x secs
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What is Data compression?
Is encoding data so it uses fewer bits than the original representation, usually used to reduce file size.
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What are the two ways to compress data?
Lossy and Lossless.
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How is data compressed using Huffman trees?
The most frequent data is coded with the less binary values, the less frequent a character is the more complex binary values are used.
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How many bits for each character does ascii have?
7 bits
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How can data be compressed using RLE?
RLE is a basic form of data compression that converts consecutive identical values into a code consisting of the character and the number marking the length of the run. The more similar values there are, the more values can be compressed. The sequence of
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Represent 0000011100000011 in RLE.
5 0's, 3 1's,6 0's, 2 1's.
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What are the 4 logic gates you would know?
NOT
AND
OR
XOR
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What is System Software?
Is software that is used by the computer in order to keep running.
- Operating System.
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What is a application software?
A software that enables the user to do a task.
- Internet Browsers
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What is a Operating System?
controls the general operation of a computer, and provides an easy way for us to interact with computers and run applications.
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What is the 5 Operating systems.
Mac OS X
Linux
Windows
Android IOS
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What are the functions of the OS?
- Provides an interface
- Manages the CPU.
- Multi-tasks
- Manages Memory
- Manages Peripherals
- Organises files
- Provides Security
-Provides tools (utilities) for managing and organising hardware.
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What types of programming languages are there?
- Low level language
- High level language
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What is Machine code?
It is language made up of binary coded instructions that is used directly by the computer.
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What is low-level language.
Is a programming language that provides little or no abstraction from a computer's instruction set.
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What is high-level language.
Is a programming designed to allow people to easily understand and write code usually in English phrases.
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What is a compiler?
A compiler is a computer that translates source code to byte code then into machine code by the whole program.
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What is a interpreter?
An interpreter is a program that executes source code by reading it line by line, this is good for picking out errors in lines but is time inefficient.
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What is a assembler?
A program that translates assembly language into machine code.
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What is the Differences between low-level and high-level languages.
- A High level language uses abstraction while low level languages uses little to no abstraction.
- High level languages is easier to write and understand compared to low level languages.
- Low level languages can be executed quicker than a high level one
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What is similar between machine code and assembly language?
They are both low level languages and have a 1:1 correspondence.
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Why is assembly language used?
It is often to develop software for embedded systems and controlling specific hardware components.
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Why does programming languages have to be translated?
Computers can only understand machine code, so every programming language have to convert themselves to machine code.
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How is machine code expressed?
In binary.
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What is the Adv and Div of Low level languages?
Adv:
- Memory efficient
- Code is fast to execute
Div;
- Hard to understand and write
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What is the Adv and Div of High level languages?
Adv:
- Easy to learn to write and understand
- Uses commands similar to English
- Takes less time to code something because of commands.
- The programmer has lots of data structures to use.
Div:
- Less memory
- Code can be slower to execute if not optimis
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What is non volatile memory?
Non - volatile is typically used for secondary data such as retaining data after the computer has been turned off, such as HDD's and ROMs
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What is Volatile memory?
a type of memory whose contents are erased when the system's power is turned off or interrupted such as RAM.
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What is RAM?
- Random Accessed Memory -
It holds things while they are running.
- The operating system
- Applications software
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What is ROM?
- Read Only Memory -
It retains its memory after the computer is turned off, ROM is used to store instructions for it to boot up again.
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What is Cache?
Cache memory is used to store program instructions that are frequently used by the CPU rather than going to retrieve information from somewhere else in the system.
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What is a Register?
A register is a component to store all location addresses to different parts of the system, or are tiny super fast memory built for a specific instruction.
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What are the 3 types of secondary Storage?
- Solid, Optical and Magnetic.
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What does a Magnetic storage device do?
Uses an magnetic disk with an arm, that goes over a drive head which is comprised of tracks, each track has tiny iron particles which has a magnetic charger of either 1 or 0, the arm goes over the disk to read either it is a 1 or a 0.
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What are the Adv and Div of a Magnetic storage?
Adv:
- Very large data capacity
- Data is not lost when you switch off the computer
- Cheap per MB compared to other storage media
Div:
- Moving parts can fail.
- Crashes can damage the surface of the disk.
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What does a optical storage device do?
Uses refracted light to read data, the surface is covered with dents(pits) and flat spots (lands). When light is reflected back on a pit it is a 1 but if it lands on a land it is a 0. The disk is rotated quickly along each line shooting a ray of light.
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What is a Adv or Div of a optical storage device?
Adv:
- Easy to store and carry
- Long lasting if looked after properly
Div:
- Data on CD-R or DVD-R are permanent and cannot be changed.
- Can be easily broken, scratched or damaged by heat and light.
- Expensive per GB/TB
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What does a Solid state drive do?
They can be found in three formats, they record data using special transistors that retain their state even when there is no power going to them.
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What are the Adv and Div of a Solid State drive?
Adv:
- Read speeds are faster than normal drives.
- Light weight
- Very durable
Div:
- Limited storage capacity when compared to normal magnetic drives
- Cost per MB stored is higher than magnetic drives.
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What is Cloud storage?
The storage of data online in the cloud.
You can access this data anywhere in the world as long as you are connected to the internet.
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What is the Adv and Div of cloud storage?
Adv:
- Unlimited storage capacity
- Automatic backup
- Universal access
Div:
- Requires reliable internet connection
- Cloud storage will not work as well with low - speed connections
-The user loses control of what happens to the data as it is managed by
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What is a computer Network?
When two or more computer are connected together to communicate to exchange data and information.
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What is a PAN?
Personal Area Network, is a small network such as phones, Bluetooth and are based around an individual person.
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What is a WAN?
Wide Area Network, WAN's are used to link LANs together, usually from a few tend of metres to thousands to kilo metre an example is the internet.
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What is a LAN?
Local Area Network
LANs are characterised by high-speed transmission over a restricted geographical area. Usually owned by an organisation or a single person.
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What is a wired network?
a configuration that involves cables which establish a connection to the Internet and other devices on the network. Such as Bus and Star Topologies
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What is a Wireless Network?
When a network uses wireless data connection in order to connect to other wireless devices such as an antenna, radios, mobile phones and televisions.
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What is the Adv of using wireless networks compared to wired networks.
Adv:
- is the freedom of not using cables and having a range
- You can connect to public WIFI networks and be able to access them
- Can be easily expanded.
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What is the Div of using wireless networks compared to wired networks.
Div:
- Data can be intercepted.
- The speed on the network is much more slower compared to wired.
- Insufficient for a large building.
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What is ethernet?
Ethernet is a family of wired computer networking technologies, used in networks.
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What is Wi-Fi?
Wi-Fi or WiFi, is a family of wireless network protocols.
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What is TCP?
Transmission Control Protocol.
It received data from the server, any lost data is requested, it is complex but more reliable and is used with application that require high reliability and transmission time is not as important.
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What is the UDP?
User Datagram Protocol.
When data is sent there is no guarantee it will arrive. UDP is faster but provides no reliability, UDP is suited for applications that need fast efficient transmission. Messages are also not ordered and may arrive in different orde
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What layers does the TCP go through?
Application layer
Transport layer
Network layer
Link layer
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What is IP?
Internet Protocol.
a protocol, or set of rules, for routing and addressing packets of data so that they can travel across networks and arrive at the correct destination.
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What is HTTP and HTTPS?
Hyper text transfer protocol (secure)
It is used for data in the application layer, to send data between your browser and the website you are connected to, the 'S' just means secure and is encrypting all the communications between your browser and the web
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What is FTP?
File Transfer Protocol and is a standard protocol that is used to transfer files from one host to another host either TCP or the internet.
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What are the 2 Email protocols?
Simple Mail Transfer protocol - used to send and receive email and can only send email if the recipients computer is on.
Internet Message Access protocol - used by email clients to retrieve email messages from a mail server over a TCP connection.
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What does the application layer and transport layer do?
- Application layer - provides applications for file transfer, remote control and internet activities.
- The Transport layer - Main interface for all network applications such as UDP and TCP
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What does the network layer and link layer do?
- The network layer - Selects and manages logical path for data transfer between nodes like IP.
- The Link layer - Handles the physical link in a network such as communication and sending packets as well encoding packets
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What is Cyber Security?
processes, practices and technologies designed to protect networks, computer, programs and data from attack, damage or unauthorised access.
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What is software?
The programs and other operating information used by a computer.
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What is Hardware?
The physical components of a computer.
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What is social engineering?
The art of manipulating people so they give up
confidential information.
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What is malicious code?
unwanted files or programs that can cause harm to a computer or compromise data stored on a computer.
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What is misconfigured access rights?
when user accounts have incorrect permissions.
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what is pharming?
When user accounts have incorrect permissions.
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What is penetration testing and what it is used for?
Penetration testing is the process of attempting
to gain access to resources without knowledge
of usernames, passwords and other normal
means of access. It is usually used for companies to test out their cyber security.
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Explain what is Blagging.
Blagging is the act of creating and using an
invented scenario to engage a targeted victim in
a manner that increases the chance the victim
will divulge information or perform actions that
would be unlikely in ordinary circumstances.
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Explain what is Phishing
Phishing is a technique of fraudulently obtaining
private information, often using email or SMS.
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Explain what is Shouldering
Shouldering is observing a person's private
information over their shoulder eg cashpoint
machine PIN numbers.
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What is Malware?
Malware is an umbrella term used to refer to a
variety of forms of hostile or intrusive software.
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Explain what is a Computer Virus?
A Computer virus is a self-replicating program, that infects existing programs and can be easily spread from one computer to another. A virus attempts to make a computer system or data files unreliable.
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Explain what is Spyware?
Spyware is malware that secretly collects and records your confidential data such as keylogging, they may not cause harm to the system, in order to have less suspicion.
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Explain what is a Trojan?
A Trojan is malware that is pretending to be another program in order to be ran, and may have a set countdown until it is active.
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What are Biometric Devices?
A Biometric Device authenticates a persons identity by translating a personal characteristic.
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What are Password systems?
A password system is a phrase that you think of, in order to access your account you put in this phrase and then the system will verify the password.
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What are email confirmations.
Email confirmations are checking if the user is using the correct email and will send a link for the user to press. An Email Verification however will require the person when signing in to access their emails and click a link to verify they are them.
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What is CAPTCHA?
Completely Automated Public Turing Test is to tell humans and computers apart, usually requiring the user to input a series of number, letter or words in order to confirm it is not a computer.
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What are Automatic Updates?
Automatic updates are to patch out any holes within a system. If not a malware will abuse this flaw in the system causing damage to your computer.
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What is
SELECT
FROM
WHERE
SELECT record
FROM table
WHERE condition
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What are the SQL commands for INSERT?
INSERT INTO <table> (<field1>)
VALUES (<value1>)
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What are the SQL commands for UPDATE?
UPDATE <table>
SET <fieldname> = <value>
WHERE <fieldname> = <condition>
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What are the SQL commands for DELETE
DELETE FROM <tablename>
WHERE <fieldname> = <condition>
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Other cards in this set

Card 2

Front

What base does computers usually use to represent all instructions and data?

Back

Binary.

Card 3

Front

Why is hexadecimal often use in computer science?

Back

Preview of the front of card 3

Card 4

Front

Convert,
01010110
to decimal.

Back

Preview of the front of card 4

Card 5

Front

What is 25 in hexadecimal?

Back

Preview of the front of card 5
View more cards

Comments

mugmaniac

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CHEESE EZ NO DIFF KEYCARDS

mugmaniac

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(i did not know there were Boolean operators in the PAPER!!!!)

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