last minute Flashcards
What is a number base?
The amount of symbols, notations it used to represent value
How many digits are in it’s number system
What is a character set?
A group of characters that a computer recognises from their binary representation
What is data compression?
The method is reducing file size , while trying to make the compressed file s true to the original as possible.
What are some uses of data compression?
0️⃣smaller files take up less storage on a device
0️⃣streaming and downloading files from the internet is quicker as they take up less bandwidth
0️⃣allows web pages to load more quickly into web browsers
0️⃣Emails have restrictions on size, but with compression you can send attachments
What is Lossy compression?
Permanently removing data from the file , to limit the number of bits the file needs , therefore reducing space.
✅less bandwidth
✅reduce a lot of file size
❌cannot be used on text or software files
❌cannot regain original file , but the worse quality is normally unnoticeable
MP3 , AAC ,JPEG
What is lossless compression
Data is removed temporarily, so reduction in quality. then restores to it’s original state ✅can be Used for software and text files ❌only slight reduction in file size FLAC, TIFF, PNG
Huffman
Lossless data compression
- Make a frequency tally for the amount of times a letter was used
- Order it from lowest to highest
- put the two lowest together and addd the Total, keep on branching off until all the values are done.
- Zeros on the left hand side
- On the chart add the new binary values
Run Length Encoding
Another form of lossless compression
1. Count the number of times the same data is repeated and store this instead
2. Store the information as data pairs
(Number of pixels, colour)
Times number by 8 and colour by colour depth and add it all together
3. Compare this to the previous by timing width and height of pixels by colour depth.
What is the function of system software?
system software manages the computer system resources and acts as a platform to run application software
What is the function of the operating system?
A collection of programs that manage and control the computer. Connects the hardware with the software
Embedded system
Dedicated systems within a larger system
Only have ROM,
Cheaper
Less power required- batteries
Pros and cons of high and low level languages
*low language is efficient use of hardware available
Compiler pros and cons
✅programs run quickly , as have already been translated
✅only needed once to create an executable file , which is then portable
❌source code must be re-compiled every time the programmer changes the
program
❌code must be completely error free to compile
Interpreter pros and cons
✅once an error is found , the program is stopped, debugging is easier
✅✅
❌no executable file is made , so an interpreter is needed each time the program want to be run
❌program run more slowly , as code is being translated ❌
Low Level languages pros and cons
LL ✅= more control over program , program can be made with less memory use (more efficient)
Greater control over CPU, program may bee needed to run quicker
Maintain old code / hardware
❌=
Harder to read and learn ,
Only works for one type of machine and architecture
what are some advantages of embedded systems ?
✅Use ROM instead of RAM for main memory , which is cheaper
✅more reliable, require less maintamce and lasts longer
Why might assembler language be used ?
More readable than machine code, Easter to write and edit programs
assembly language has a 1:1 correspondence with machine code
What are advantages and disadvantages of cloud storage?
:)can be accessed from anywhere,
data can be shared ,
cheap,
provides back up/security
:( need Wi-Fi,
data vulnerable to hackers,
Why choose a high level language?
🟡High level have built in subroutines
🟡Provides programming structures such as iteration and selection
🟡Easier to debug
🟡Easier to understand (more easier to read)
What is a computer system?
Two or more computers , that are CONNECTED together that are able to exchange data with each other. Allowing software and hardware to be shared.
What are the advantages of networks?
🟢communication eg: emails & text messages
🟢file sharing , eg: stored centrally and worked upon centrally
🟢hardware sharing , eg printers , making it more cost effective
🟢user account allow you to log in from any device
🟢installing software centrally , takes less time
What are some disadvantages of networks?
🟣expensive to set up as a lot of hardware is required. eg: NIC cards, switched , cables
🟣vulnerable to hacking and malware which can spread to networked computers
🟣hard to maintain and install , may require employing a specialist
Advantages wireless 🟢networks:
🟢Wireless are cheaper to set up.
🟢Wireless also requires less information and installation is automatic.
🟢wireless can add people more easily
Advantages of wired networks🔴
🔴wired have a larger transmission speed, higher bandwidth, more reliable
🔴wired are more secured. As physical connection is needed to intercept data
🔴wired have no interference from other Wireless networks or physical obstructions like walls
What is a WAP?
Wireless access point
Needed in wireless networks
Basically a switch needed to connect devices wirelessly
What are routers?
Transmit data between different networks
Used to connect to the internet
Star network pros and cons
✅if a device fails the network is unaffected
✅fewer data collisions as all devices can transmit data at the same time
✅easier to add devices
✅packets only sent to intended devices
❌expensive as it requires a switch and other hardware
❌problem with switch then the whole network is affected
Pros and cons of Bus networks
✅if one device fails the network remains unaffected
✅cheap to set up and maintain
✅not dependant on a switch
❌frequent data collisions slowing the network down
❌unsuitable for large networks as too many data collisions
❌network fails if the backbone cable is broken
Describe IP and it’s purpose
Internet protocol,
🟣give them an IP address ,
🟣used to route the journey for packets by according to traffic
Responsible for packet switching
An IP adresss is a number code gIven to every device in the network
What does the application layer do , and what are some examples?
Network applications like web browsers or email programs operate
Eg: HTTP, HTTPS,FTP,SMTP.IMTP
What does the transport layer do, and what are some examples?
🔵sets up communication between 2 hosts
🔵make the size of packets
Eg:TCP,UDP
What does the internet layer do, and what are some examples?
🔵addresses and packages the data for transmission
🔵routes the packets across the network
Eg: IP
What is the link layer, and what are some examples?
Passing data over a physical network, data sent as electrical signals over cables , wireless and other hardware
🔵network hardware is located
What is authentication, when would it be used?
🟣takes one or more specific data from a user
🟣only allows access to the system if credentials are valid
Preventing unauthorised access
eg: username and password
What is MAC address filtering and when is it used?
🔵takes a MAC address for each device
🔵checks to see if it is in the list of allowed , and on that basis gives it permission to connect to the system
Compare bus and star
🚎 isn’t reliant on central switch/server, ⭐️ will completely fail if central device stops working
🚎 less cabling (no switch) and so are cheaper than a ⭐️
⭐️ all devices can access the switch simultaneously, so there are no data collisions, 🚎 data collisions are common
Why is network security important?
🟠prevent cyber attacks(targeting specifics)
🟠prevent unauthorised access
🟠protects data and programs against damage
What is Pharming?
redirects the user from a websites’s traffic to a fake website , in hope to gain personal information , to access their genuine account
How could you prevent pharming?
- anti-malware software , up to date
- internet browsers using web filters
*not clicking or links or attachments from unknown users
What Phishing?
A technique if fraudulently obtaining private information, often using email or SMS
emails are sent to the user claiming to be from well known business, asking for bank details
what is penetration testing?
organisations employing specialists to stimulate potential attacks to their system, allowing them to identify their weaknesses in cyber security
The process of attempting to gain access to resources without knowledge of usernames, passwords and other normal means of access.
What is the difference between white and black penentration testing ?
white: when the person or team testing the system has knowledge of possibly basic credentials for the target system, stimulating an attack from inside the system (a malicious insider)
black: when the person of team testing the system has no knowledge of any credentials for the target system, stimulating an attack from outside the system (an external attack)
How do orgainsations keep their networks safe from threats?
- encryption, to prevent wire tapping or packet sniffing
- anti-malware software
- firewalls
- user access levels, stops attacks from within the organisation
- automatic software updates
- MAC Address filtering
*penetration testing (white & black) to find weaknesses and correct
*strong, regularly changed passwords, against automated software.
Describe encryption
data translated into cipher text, with the correct key to decipher, data can now be sent over a network securly
What are some types of security measures ?
- email confirmation
- biometrics
- CAPTCHA
- passwords
*automatic software updates
CAPTCHA
completly automated public turning ( to tell) computers and humans apart
✓prevents programs from automatically doing things (creating user accounts)
What is ‘cyber security’?
The processes , practices and technologies designed to protect networks, computers, programs and data from attack, damage or unauthorised access
Change the age of Molly from 5 to 6
Delete all the black spaniels from the table
What are some advantages of relational databases ?
🔵data is only stored in one place and then referenced. This means that to input , update or delete pieces of data, it only has to be done in one place which can prevent inconsistencies
🔵only storing the same price of dat once will also save storage space
🔵relational databases can be more secure , some tables can be made more confidential so only some users can see certain data (helps companies meet data protection laws)
How do you insert a full record into a table ?
How would insert bits of a record into a table ?
