Computer Systems Flashcards
What do computers store all data as?
Binary numbers (base 2, 1s and 0s)
How are integers stored
Twos complement
Range of positive integers?
2^n‐¹ -1
Range of negative integers
-2^n‐¹
How do you know if binary is positive or negative?
Most significant bit (MSB) 0=POSITIVE 1=NEGATIVE
How are real numbers stored?
Using floating point representation
Mattissa determines what?
The accuracy of the number
Exponent determines what?
The range of the number
Increasing the number of bits for the Mantissa and decreasing the number of bits for the exponent does what?
Increases accuracy but decreases range
Unicode advantages?
Represents a large variety of languages including emojis UTF-16 HAS 65 536 characters UTF-32 HAS over 4 mill
Unicode disadvantage?
Takes up double the storage
Bitmap advantages
- Able to edit at pixel level
- Realistic images
- Same appearance in all systems regardless of hardware or software.
Bitmap disadvantage?
- Scaling causes pixelization
- Only the image can be edited.
- Difficult to convert to vector formats.
- File sizes can be large.
Vector graphic advantages
- Individual objects can be easily edited
- Smaller files
- Can be scaled to large sizes, keeping quality.
Vector graphic disadvantages?
- Unable to edit on pixel level
- Unrealistic images
- Resolution dependent
Bit depth
Number of bits used to store each pixel in a image
Fetch execute cycle
- The processor sets up the address bus with the required address.
- The processor activates the read line on the control bus.
- An instruction is fetched from the memory location by the data bus and is stored in the Instruction register.
- The instruction in the instruction register is interpreted by the processor, decoded and carried out.
Number of cores
More cores the more instructions the processor can process
Width of the data bus
By increasing the data bus from 32 to 64 wires the computer can transfer twice as much info at one time
Cache Memory
Small fast accessible memory. the processor checks the cache before the main memory for data or instructions
Clock speed
Clock pulses are used to trigger components to take their next step. The higher clock speed, the faster the computer completes a set of instructions. but at the cost of increased power consumption and overheating
Heating system
Knows when the house is empty so turns off heating, checks weather forecast.
zoning GPS data
reduces co2
traffic control
transport emits 25% of co2 emissions.
Adaptive traffic signals
intelligent routing systems
Car management
Start/stop system
Air to fuel ratio
Computer Missuse Act 1990
Unauthorised access to computer material6 months
unauthorised access with intent to commit or facilitate a crime 5yr
unauthorised modification of computer material 5yr
Tracking Cookies
A tracking cookie is a small data file created when you access a website. Tracks web browsing data about you so it can target ads at you. Can pose a risk as the TC can be sell your account details and data to a 3rd party company
DOS symptoms
inability to access or slow performance
DOS effect
DOS COST AND REASON
DOS TYPE
Bandwidth consumption
Bandwidth consumption is when a flood of requests fills the connection up to its limit so no other requests can get through. The effect only lasts as long as the attack is maintained.
Resource starvation
is when the requests take up a few other resources, like disk space until the server runs out and is no longer able to function correctly
DNS Dmain name service
These attack the servers that route internet traffic so it can impact multiple websites. It also can lead to congestion and consumption of bandwidth.
Encryption key
Public key
PRibate key
Sym
An encryption method in which the same key is used to encrypt and decrypt a message
DIgital cert
A digital version of passport that confirms the identity of a person or organisation. This allows individuals and companies to feel secure in exchanging information as they can confirm each other’s identities.
Digital signature
Is an electronic siganture that is used to validate the identity of the person sending a message or the integrity of a document
digi sig
A digital signature is a method of ensuring that a message is authentic (unaltered).
You obtain a message hash (A mathematical summary of the contents of the message).
You can encrypt this message hash (this time with the private key as this has to be private - hence the private key).
This ‘signature’ is attached to a message.
