Paper 1 Flashcards
what does a computer system consist of?
hardware and software that works together
what is an embedded system?
computer inside a larger system
feature of embedded systems and why?
because they only do 1 task, they’re usually cheaper, more efficient and easier to design
name 5 main hardware components?
- motherboard
- optical drive
- ram sticks
- CPU
- hard disk drive
- power supply
- graphics card
- case cooling fan
what does the CPU do?
processes data and instructions that make the system work
what does CPU architecture describe?
the main CPU components, how they interact with eachother and other parts of the computer system
name 3 features of the control unit?
- manages fetch-execute cycle of program instructions
- in overall control of the CPU
- controls flow of data inside and outside the CPU
3 features of the arithmetic logic unit?
- does all calculations
- performs AND, OR, NOT operations and binary shifts
- contains the accumulator register in the CPU
4 features of cache?
- high-speed memory in CPU, slower than registers but faster than RAM
- stores regularly used data, so it can be accessed quicker when needed
- low capacity and expensive
- 3 levels, L1, L2, L3
What is von neuman architecture?
a system where CPU runs programs from memory
2 feature of the program counter
- in control unit
- holds the memory address of the instruction for each cycle
what does the accumulator do?
stores intermediate results from the ALU
what does the memory address register do?
holds any memory address’s about to be used by the CPU
what does the memory data register do?
holds the actual data or instruction
what cycle does the CPU follow?
fetch - execute cycle
2 steps of fetching?
1) copy memory address from PC to MAR
2) copy the instruction from the MAR address to the MDR
what happens when decoding?
instruction in the MDR is decoded by the control unit
what is RAM?
high speed, volatile, main memory
what is main memory?
where everything is stored while being used
when do things leave RAM?
when they’re closed
what happens when the computer boots up?
the operating system is copied from the ROM to the RAM
what is virtual memory?
secondary storage used as extra RAM
when is virtual memory used?
when RAM is full
what does ROM do?
tells the CPU how to boot up
where is ROM?
comes on a small chip in the motherboard
what is primary storage?
any memory areas the CPU can access quickly
how is data stored on a hard disk drive?
magnetically
what is the traditional storage medium?
HDD
4 features of HDD’s?
- high-capacity
- reliable
- cheaper
- longer read/write life
4 features of SSD’s?
- fast
- doesn’t need defragmenting
- silent
- more shock-proof
what are solid state drives?
fast, reliable secondary storage
what are optical disks?
cheap, robust secondary storage
what are the 3 forms of optical disks?
- read-only
- write-only
- rewritable
3 features of optical disks?
- cheap
- portable
- shock and water proof
what are magnetic tapes used for?
archiving
name all 8 units in order, smallest first?
- bit
- nibble
- byte
- KB
- MB
- GB
- TB
- PB
how many bits in a nibble?
4
how many bits in a byte?
8
what are character sets?
a collection of characters that a computer recognises from their binary representation
why must characters be converted?
computers can only process binary
what are the 2 character sets?
- ASCII
- unicode
which is the most commonly used character set?
ASCII
how many bits are used to represent ASCII?
7-bit binary, but aa 0 is added infront so it fits into 1 byte
what is the calculation for file size of characters?
num of bits per character X num of characters
what are images stored as ?
a series of pixels
what is the colour of a pixel represented as?
a binary code
how many bits per pixel are needed for a black and white image?
1
how can you make a greater range of colours and shades per pixel?
increasing number of pits per pixel
what is the calculation for number of colour in an image?
2 (to the power of number of bits per pixel)
what is colour depth?
number of bits per pixel
what is image resolution?
number of pixels in an image
what are the 2 calculations for file size of an image?
image resolution X colour depth
- width X height X colour depth
what is metadata?
information about the image
what is sound recorded as?
an analogue signal
what is an analogue signal?
pieces of continually changing data
what is sampling?
converting analogue to digital
name 2 factors that affect sound file size and quality?
- bit depth
- sample rate
what is bit depth?
bits available for each sample
what is sample rate?
how many samples taken per second
calculation for sound file size?
sample rate X bit depth X length
what does increasing bit depth do?
means digital files can pick up lower sounds
what is data compression?
when a file size is made smaller, while being tru to the original
4 advantages of data compression?
- files take up less storage
- streaming and downloading is quicker
- web pages load quicker
- file can fit email service restrictions on file size
what is lossy compression?
works by permanently removing data from the file
what is losseless compression?
temporarily removes data to store the file, and then restores it to the original when opened
name 3 pros of lossy compression?
- greatly reduced file size, so more files can be stored
- commonly used, can be read
- take up less bandwidth, so can be downloaded quicker
name 2 pros of lossless compression?
- no reduction in quality
- can be used in text or software files
name 3 cons of lossy compression?
- file loses data
- cant be used on text or software files
- worse quality than original
name a con of lossless compression?
only slightly reduced file size, so still takes up quite a bit of space
name 3 pieces of network hardware?
- network interface controller
- switches
- routers
what is a network interface controller?
an internal piece of hardware built into the motherboard that allows a device to connect to a network
name 2 things switches do?
- connect devices on a LAN
- recieve data from 1 device and transmit it to another on the network
name 3 things routers do?
- transmit data across networks
- on the internet, they direct data to their destination
- connect LANS to the internet
name the 2 types of basic cable?
- cat 5
- cat 6
name the 2 types of advanced cable?
- coaxial cable
- fibre optic cable
name 3 features of fibre optic cables?
- transmit data as light
- very expensive
- very high performane
describe the structure of coaxial cables?
a single copper wire surrounded by plastic insulation and metal mesh to stop interferance
does wifi have a high or low bandwidth, compared to bluetooth?
high bandwidth
what is a network protocal?
a set of rules for how devices communicate
what addresses does communication over the same network use?
MAC address
what addresses does communication over different networks use?
IP address
how are MAC addresses assigned?
assigned by the manufactuer
how are IP addresses assigned?
assigned manually or automatically before a device can access a network
why are MAC addresses needed?
so they have a unique identifier that can be found on the internet
how are MAC addresses displayed?
- either 48 or 64 bit binary code
- converted to hex for ease
what addresses are used when sending data over the internet?
IP address
what does the TCP do?
sets rules for how devices connect on the network. in charge of splitting data into packets and reassembling after theyve been sent
what does the IP do?
responsible for directing packets to their destination across the network
what is HTTP used for?
used by web browsers to access websites and servers
what is HTTPS used for?
a more secure version of HTTP
what is FTP used for?
to access, edit and move files between devices on a network
what is POP3 used for?
to retrieve emails from a server. the server holds the email until you download it, then its deleted from the server
what is IMAP used for?
to retrieve emails from a server
what is SMTP used for?
to send emails
how many network protocol layers are there?
4
what does network protocol layer 1 cover?
passing data over the physical network
what does network protocol layer 2 cover?
making connections between networks and directing data
what does network protocol layer 3 cover?
controlling data flow
what does network protocol layer 4 cover?
turning data into websites and other applications
name 2 advantages of using layers?
- breaks network communication into manageable pieces
- changing 1 layer wont affect others, as they are self contained
name 5 types of network attacks?
- passive attack
- active attack
- insider attack
- brute force attack
- denial of service attack
what is malware?
software that can harm devices
name 5 typical actions of malware?
- deleting or changing files
- scareware
- locking files
- spyware
- opening backdoors
- rootkits
name 3 types of malware?
- viruses
- worms
- trojans
what is the difference between worms and viruses?
worms self-replicate without user help
what is social engineering?
a way of gaining information on or illegal access to networks by influencing people
what is phishing?
a type of social engineering that involves criminals sending emails to trick people
name 6 malware prevention methods?
- penetrative testing
- physical testing
- passwords
- user access levels
- anti-malware software
- encryption
what is a client-server network?
network that is managed by a server and the devices connected are clients
what is a peer-peer network?
network where all devices are equal and are connected to eachother
describe a mesh topology?
where all devices are connected to eachother
describe a star topology?
all devices are connected to a central switch or server
describe a bus topology?
all devices are in a line and are connected to a single backbone cable
describe a ring topology?
data moves in one direction around the ring to avoid collisions
what is a VPN?
a private network deployed over the internet
what is DNS?
a name database in which domain names are converted to IP addresses
