Computer Systems Flashcards
How to calculate two’s complement?
Copy positive numbers from the right until you get to a 1
Example -20
128 64 32 16 8 4 2 1
0 0 0 1 0 1 0 0
1 1 1 0 1 1 0 0
How to calculate the range of numbers?
Remember to -1 from the amount of bits and put into this formula:
-(2^x-1) to (2^x-1) - 1
Example: 8 bit
-(2⁷) to (2⁷) - 1
What do the mantissa and exponent affect?
Mantissa = Accuracy
Exponent = Range
How to figure out signed bit for floating point representation?
0 = positive
1 = negative
Rule for matissa in floating point representation?
Add extra 0’s to the end until it’s equal to 15, remove any decimals points
How to figure out exponent in floating point representation?
110110.011 Go to the left so exponent is 6
0.00101011 Go to the right so exponent is -3
-1101.010101 Go to the right so exponent is -1
-0.01011 Go to the right so exponent is -1
What are some advantages and disadvantages of ASCII
Advantages:
-Uses less storage space (8 bits)
Disadvantages
-Can’t represent many languages
-Can’t represent many symbols/characters
What are some advantages and disadvantages of Unicode
Advantages:
-Represents a lot more languages
-Represents lots of symbols and characters
Disadvantages:
-Uses more storage space (16 bits)
Facts about vector graphics?
- It attributes such as position (x, y), stroke colour, shape, line thickness
- Everytime the drawing package is loaded it redraws all the shapes
- it’s scaleable and doesn’t lose clarity
- Ideal for cartoons and logos
- Small file size
Facts about bitmap graphics?
- When zoomed in becomes “jaggy”
- Each individual pixel can be controlled
- Ideal for photos
- Big file size
What are parts of a computer?
- address bus
- control bus
- data bus
- processor
- registers
- RAM
- cache
What is the read fetch-excute cycle?
1 Address bus is set up with memory address location
2 Read line activated on control bus
3 Instructions loaded onto data bus
4 Instructions put into processor to be de coded and executed
What is the write fetch-excute cycle?
1 Address bus is set up with memory address location
2 Data bus is set up with the data to be stored in RAM
3 Write line activated on control bus
4 Data on data bus stored in location specified by address bus
What are factors that affect performance?
- more cores in processor
- Increasing width of data bus
- Increasing size of cache memory
- Higher clock speed
What does adding more cores to the processor do?
It can process more sets of instructions it can recieve and process at the same time
What does increasing the width of the data bus do?
Increases the amount of data transferred per tick/per cycle
What does increasing the size of cache memory do?
This means frequently used instructions can be accessed quicker because it has faster access than RAM
What does having a higher clock speed do?
It means the computer can process instructions quicker, still one at a time
What are the intelligent systems that have an environmental impact?
- Intelligent heating systems
- Intelligent traffic control systems
- Intelligent car management systems
What is an intelligent heating system?
Adjusts heating depending on if anyone is home or in a particular room, it doesn’t waste energy by heating the house when it’s empty
What are intelligent traffic control systems?
Uses cameras and sensors to lessen congestion and keep traffic moving, this reduces the amount of harmful emissions (CO2)
What is an intelligent car management system?
Start-stops systems turns engine off when the car is idling so it reduces fuel consumption and carbon emissions
What is a tracking cookie?
It’s a small file created when accessing a website that gathers your information and is distributed between different websites, to present customised data
What does DoS attack stand for?
Denial of Service attack
What are the causes of a DoS attack?
- Bandwidth consumption
- Resource starvation
- Domain name service attack
What is bandwidth consumption?
Flood of requests fill up connection so no legitimate requests can get through
What is resource starvation?
Affects diskspace, memory and processor (server can’t function)
What is a DNS attack?
Domain name service attack is when the server the website is routed through gets attacked, this affects multiple websites
Symptoms of a DoS attack?
Slow performance or inability to access resources on server
Effects of a Dos attack?
Business unable to carry out time critical actions, reputational damage, financial loss (e.g. users buy from a different company)
Reasons for Dos attack?
Financial: Attacker could demand payment to stop
Political: Take down governement websites as a form of protest
Personal: Grievance against company, for revenge
What is encryption?
It scrambles a message so it can only be read by the intended reciepent
How does encryption work?
Two key are mathematically linked
Public key encrypts
Private key decrypts
What is a digital signature?
It’s a way to ensure an electronic message/document is authentic
How does a digital signature work?
It is created using a private key, then paired with a public key sent with the message, it’s decrypted with the public key if that matches the hash algorithm it is authentic
What is a digital certificate?
A certificate is used to check if you’re sent a message the person is who they claim to be and it binds their public key to them. They can only be issued by a central certification authority.
How does a digital certificate work?
It’s the digital equivalent of a passport or divers licence, it contains a public key, owners name and the expiration and issuer
What is the computer misuse act?
- unauthorised access to computer material
- unauthorised access with intent to commit a further offence
- unauthorised modification of programs or data on a computer
What does GDPR stand for?
General Data Protection Regulation
What are the 8 rights protected by GDPR? (Name at least 3)
-Right to be informed
-Right to access
-Right to rectification
-Right to erasure
-Right to restrict processing
-Right to data portability
-Right to object
-Right to not be subjected to automated decisions
