Computers Flashcards
whatare the components of the CPU
- control unit
- decoder
- clock
- arithmetic logic unit
- buses
- cache
- registers
what is the function of the control unit
- controls all other components in CPU
- Contains the decoder
what is the function of the decoder
- interprets program instructions
- tells the ALU what operations to do
what is the function of the clock
- Controls rate which program instructions are carried out
- Sends control electrical signals in cycles
what is the function of the arithmetic logic operator
-Arithmetic and logical operations done to carry out program instructions
what is the function of the buses
-Electrical conductors that carry electrical signals in the CPU and btwn the CPU and other components on the motherboard
what is the function of the registers
- memory locations.
- some perform special functions in the fetch-decode-execute cycle
what is the function of the cache
- very fest random access memory (RAM)
what factors affects the performance of the CPU
- clock speed
- cache size
- number of cores
- type of RAM
- hard drive speed
what does it mean if a processor is quadcore
it can carry out 4 instructions at the same time
what is clock speed
- the amount of clock cycles that take place within one second
- measured in gigahertz (GHz)
- CPU carries out one instruction per clock cycle
what is the purpose of the CPU
- To fetch and execute program instructions stored in memory.
- often referred to as Von Neumann architecture
name all four different types of registers in the CPU
- program counter
- MDR (memory data register)
- accumulator
- MAR (memory access register)
what is the function of the program counter (register)
- holds the address of the next instruction to be fetched.
- uses the fetch-decode-execute cycle
what is the function of the MDR (memory data register)
- temporary store for anything copied from memory
what is the function of the accumulator (register)
- stores the results of calculations carried out by the ALU
what is the function of the MAR (memory access register)
- holds the address of the memory location currently being read/fetched or written to
- uses the fetch-decode-execute cycle
why is the performance of the CPU affected by the number of cores you have
- more cores = more instructions can be carried out per second therefore the computer will be quicker
explain why a computer with a 2.2GHz CPU might be considered preferable to one with a 1GHz CPU
- the clock sends out electrical control signals at regular intervals.
- the rate of the pulses affect the execution of instructions by the CPU
- the 2.2 GHz CPU can carry out 2.2 billion processing cycles per second so is faster than the 1 GHz CPU that can carry out 1 billion processing cycles per second
identify 3 components of a CPU and state their role within the fetch-decode-execute cycle
- the CU controls all the other components of the CPU and decodes all insturtions
- the buses carry electrical signals & data to be stored btwn CPU and RAM
- ALU performs arithmetic and logical operations to carry out program instructions
what is the fetch - decode - execute cycle?
how many cycles does it take?
- The CPU uses the fetch - decode - execute cycle to carry out the program instructions
- this cycle takes 3 clock cycles
ADDRESS BUS
used to retrieve the location of the data where the CPU must read/ write to
Operating systems control the ways in which users interact with the computer through the user interface and control peripheral devices (able to be attached to and used with a computer, though not an integral part of it.)
User interface
Allows the user to communicate with the computer
Many OS provide a GRAPHICAL USER INTERFACES (GUI) with Windows, Icons, drop down Menus and Pointers (WIMP)
Common GUIs are Windows, iOS and Android
Other interfaces just allows the user to type in commands
These are called COMMAND LINE INTERFACES
User management
On networks and shred computers the OS MANAGES USERS. Login manes/passwords are used to allocate permissions for access to files and folders
Often used in organisations to prevent individual users making changes to computer software/ making inappropriate usage of the computer
Peripheral device management
Most computer systems use peripheral devices for input & output of data
Input devices:
Keyboard
Mouse
Microphone
Webcam
Scanner
Output devices:
Printer
Loudspeaker
External/internal monitor
Headphones
External hard drives and network storage devices are also peripherals. Al peripherals are controlled by the OS using programs called DRIVERS
The drivers carry out the necessary devices to communicate correctly
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Utility software is a collection of tools, each of which does a specific job. It helps to configure the systems, analyse how it working and optimise it to improve its efficiency
Encryption software
Encryption is the scrambling of data into a form that cannot be understood by unauthorised users. It’s used to protect data from unauthorised users of the computer. The encrypted data must be decrypted data back to its original form. Encryption/ decryption is carried out using a CIPHER or key
Defragmentation software
Data is saved to different areas of the discs where there is free space.
If the file is larger than the free space in one part of the disc, then part of the file is saved in that space and some more in another area. This is known as fragmentation
Overtime, this reduces efficiency as more disc accesses are needed to read the complete file.
Defragmentation software reorganises the files by putting pieces of related data back together, fewer disc accesses are needed to read the data.
This improves performances and can free up more space on the hard disc
Data compression software
Uses algorithms to REDUCE the size of files meaning less storage space is required & transmitting files by email/uploading or downloading using cloud services is easier
Commonly used for audio/ video files
LOSSLESS COMPRESSION reduces the size without deleting any of the data, important for text files
LOSSY COMPRESSION reduces the size by deleting some of the data
Backup
Involves copying files to a second medium i.e. a disc/tape/cloud service so they can be restored if there’s any problems with the originals
Can compress the data to take up less storage space
With a full backup, all of the specified data is backed up
With an INCREMENTAL backup only new files/ edited files with new changes applied since the last backup are saved to save time
Some backup software will copy files continuously so long as the computer is switched on. Other software will only run at specific times
State what is meant by backing up a computer
It involves the copying of data stored on a computer system onto a separate storage device ie a disc or tape
Describe the difference between a full backup and an incremental backup
In a full backup, all of the data on the computer is coped
In an incremental backup, only the data that is new/ has been changed is copied
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Computer modelling
A computer model attempts to abstract the rules and mechanisms that control real-life systems and apply the, in computer programs so that they can be used to stimulate the behaviour of those systems under different conditions. The models can be used to answer ‘what if’ questions eg what will happen if this condition is met. The simulations will only be successful if all the rules abstracted from the real-life systems are correct
Examples of simulations
FLIGHT simulations (allows pilots to train to fly passenger aircraft without the actual cost of using actual aeroplanes)
TRAFFIC FLOW simulations (models are used to simulate traffic when new roads and motorways are being planned)
WEATHER FORECASTING simulations (models are used to simulate the atmosphere and changes that affect the weather)
FINANCIAL MODDELLING (used to investigate the effect of changing tax rates when budget changes are being investigated)
Advantages of using computer models
Safety (ability to experiment without harming people or the environment)
Financial (new products can be tested without having to build prototypes ie cars/aeroplanes)
Repetition (tests can be quickly repeated to ensure similar outcomes)
Adjustments (changes to the rules and input data can be made quickly to see the outcomes)
disadvantages of using computer models
The mathematical calculations may be too complex to model real life situations
May be difficult to identify all of the rules correctly
The model is not reality so the answers may not be correct
The processing power needed to run the model may be greater than what is available
Modelling software
Specialist software can be purchased for creating specific types of model ie finance, electronics chemical reactions and biological processes
Spreadsheets can be used to model most situations as rules and formulae can be applied to specific cells and models can be created in most programming languages
Can be used to investugate effects of increasing global temperate of sea levels on the world
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Instructions for computer are written in programming languages that need to be translated into machine code before the computer can understand then
Low levels languages
Machine language (processors only understand instructions written in 1s and 0s. At the processing level computer programs are in the form of millions and 1s and 0s, known as machine code/ languages)
Assembly language (assembly language when each instruction is directly equivalent to one in machine code. Words called mnemonics are used to replace the command represented as strings of 1s and 0s in machine code ie ADD is a mnemonic used to replace the binary command to add numbers together)
Uses of low level languages
Assembly language is often used in the programs used by embedded systems ie in in cameras, microwaves and TVs as it can be used to directly control system hardware
They’re used to write device drivers and real-time systems where speed is essential
Assembly language is specific to each type of CPU. Program written for one type cannot be used on others
Uses of high level languages
Most software is developed using a high level language. Its less time consuming to write and quicker to test
Programs are portable from one machine to another
Most high level languages can be used with different types of CPU
High level languages:
Three reasons to use a high level languages for software development:
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compare the performance of: specification 1 (3GHz, 64bit CPU, 4MB cache, 4GB RAM) specification 2 (4GHz, 64bit CPU, 4MB cache, 8GB RAM)
- spec 2 would be quicker in terms of the clock speed. bc it has a higher clock cycle speed (4GHz) meaning that the clock will send more electrical impulses to the CPU and more instructions per second will be completed. However, specification 2 may be quicker because there is double the RAM available. This would mean that there would be double the instructions/ amount of data to be stored whilst the computer is running. Overall, I believe that the specification 2 will be quicker overall because the clock speed is 25% faster meaning there will be a quarter of the instructions/ processes completed whilst the computer is on
what is open source software
- Free software that users can download.
- Source code is available to users
what is the difference btwn pop and imap protocol
POP = Emails downloaded on to device IMAP = Emails stored on a server
what are protocols
- Ensures data is sent in a format that all computers can read
- Has address formats to ensure data is sent to the correct computers
- Chooses the route of the data
what are the TCP/IP layers for sending data
- Application
- Transport
- Internet
- Link
what is TCP/IP
- Transmission Control Protocol/Internet Protocol
-splits data to packets and reassembles
-Encrypts/decrypts
-Address needed
Notifies sending computer that info has been recieved
what is FTP protocol
- File Transfer Protocol
- Rules for file transfer
- Used to transfer files too large to beattached to an email
What is SMTP
- Simple Mail Transfer Protocol
- Rules for sending Emails
- Goes from client to different servers until it reaches its destinantion
What is IMAP
- Internet Message Access Protocol
- Emails stored on server
- Can be read from any device
What is HTTP protocol?
- Hyper Text Transfer Protocol
- Rules for web browser and server when requesting and supplying information
What does the application layer do?
- provides services to applications ie web browsers/email servers
- where requests are made and emails sent
- HTTP(S) and POP
What does the transport layer do?
- Puts data in packets
- Checks data has been sent/received
- Notifies sender that data has been recieved
- TCP and UDP
What are switches?
- Reads MAC address
- Sends only to recipient
- Big and expensive
What is an NIC?
- Network Interface Controller
- Used to connect to a network
- Is in chip on a motherboard of a computer
- Formats data sent and received
What is a MAC address?
- NIC’s Media Address Control (MAC)
- Ensures data directed to correct computer
What is an internet layer protocol example?
IP
What are link layer protocol examples?
Ethernet/Wifi Protocols
What’s a router?
- Connects networks
- Reads address info
- Transfers data between home network and internet
What are wireless access points?
- Convert data through cables into a wireless signal
- Doesn’t read destination addresses
- Info sent to everyone
- used for hotspot
Cable networks pros and cons (One computer)
-High bandwidth
-More secure (Just needs a plug)
-No interference
>Installation difficult
>Poor mobility
>expensive
Pros/Cons Open source software
-Free to use
-Users can change software
-Source code can be studied
>Needs specialist knowledge