Autumn term 1 Mr Reid Flashcards
What is measured in Hertz?
Clock cycles per second
A standard desktop computer has a Gigahertz of…
336
A one gigahertz processor…
executes 1 billion instructions per second
What is the technical name for simultaneous processing in multi-core computers?
concurrent processing
What is threading?
process where dif cores work on the same problem by splitting instructions
What is cache?
very small+fast memory
intermediatry between processor+RAM
What is the internet?
the physical components that make up a network of networks
What is the longest section of the FDE cycle?
fetch
what happens in the Decode section of the FDE cycle?
CU decodes instructions from CR
what happens in the Execute section of the FDE cycle?
Execute the instruction
what happens in the fetch section of the FDE cycle?
-PC holds address of next operation
-copy contents of PC to MAR
-Increment PC
-Load instructions/data pointed to by MAR to MDR
How is the internet differnet from the WWW?
The WWW is the software that runs on the internet, eg websites
What is an IP address?
A unique address that each computer has in order to communicate.
What version of IP addresses are we currently using?
Currently we’re using IP v4, which is four sets of 3 digit numbers up to 225)
Why are v4 IP addresses “running out”?
Many big companies have bought too many addresses but not sold them.
What are the four different registers?
PC, MAR,MDR,CIR
What does PC stand for?
Program Counter
What does MAR stand for?
Memory Address Register
What does MDR stand for?
Memory Data Register
What does CIR stand for?
Current Instruction Register
What does ALU stand for?
Arithmetic Logic Unit
What does ACC stand for?
Accumulator
What does the PC do?
stores the address of the next instruction
What does the MAR do?
stores the address of the data/instruction that has been found
empty card
ignore it i’ll delete it at some point
What does the CIR do?
Holds the result of calculations
What does the ACC do?
holds the result of calculations from the ALU
What does the CU do?
Synchronises the other components. The only component that can decode instructions
what does URL stand for?
universal resource locator
what does DNS stand for?
Domain name system
What does DNS technology do?
translates URLS to IP addresses
What is Moore’s law?
Every two years, computational power doubles
What are the different factors affecting network performance?
Bandwidth, latency, error rate,
what does latency mean?
latency is the amount of time a message takes to traverse a system, sometimes measured as the time taken for a data packet to be returned to sender, and sometimes from a to b
what does bandwidth mean?
The amount of data that can be transmitted in a fixed amount of time. Usually expressed in bits/bytes per second
What is error rate?
The degree of error encountered during a data transmission over a communication of data correction.
What is hosting?
network hosts are computers which may offer services, resources + apps to users.
to have a website you need a host
What is a peer to peer network?
all equal status
Each can act as client and server.
All request+provide services
What is a server network?
network w/ a central server
all clients request services from it
need additional hardware
What do LAN and WAN stand for
Local/Wide Area Network
What is a LAN?
A network where computers are connected together over a small geographical ara such as a single building or site. It uses your own infrastructure
What is a WAN?
A network where computers are connected over a large geographical area. This could be several buildings/sites, townwide, countywide or even countrywide. Uses other people’s infrastructure
Give some examples of LANs
School network, home network, network in a shop
Give an examples of a WAN
The Internet
What is topology?
the network’s ‘shape’-how computers are connected.
What are the advantages of a star topology?
-Each machine can share resources, such as printers, servers, routers, etc.
-if one member fails the network still works.
What are the disadvantages of a star topology?
extra equipment/cabling is expensieve
if the main computer fails, they all fail
What are the advantages of a mesh topology?
very quick to set up
usually uses wifi technology
can add or remove machines with ease
great for ad hoc networks
usually peer-to-peer
What are the disadvantages of a mesh topology?
not very secure
more stations, slower network- could crash
What is encryption?
a method of scrmabling data to produce data that makes no sebse without access to the key.
Why is encryption used?
on an open or public wifi network, data can be intercepted. if encryption is used, intercepted data will have no meaning.
What is the difference between encryption and coding?
coding is merely shortening the amount of data, which encryption is making the data unreadable.
What is the encryption method used when using a secure site, eg amazon/your bank/etc?
SSL- secure socket layer
