Flashcards in Computers Deck (119):
1
whatare the components of the CPU
- control unit
- decoder
- clock
- arithmetic logic unit
- buses
- cache
- registers
2
what is the function of the control unit
- controls all other components in CPU
- Contains the decoder
3
what is the function of the decoder
- interprets program instructions
-tells the ALU what operations to do
4
what is the function of the clock
-Controls rate which program instructions are carried out
-Sends control electrical signals in cycles
5
what is the function of the arithmetic logic operator
-Arithmetic and logical operations done to carry out program instructions
6
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
7
what is the function of the registers
- memory locations.
- some perform special functions in the fetch-decode-execute cycle
8
what is the function of the cache
- very fest random access memory (RAM)
9
what factors affects the performance of the CPU
- clock speed
- cache size
- number of cores
- type of RAM
- hard drive speed
10
what does it mean if a processor is quadcore
it can carry out 4 instructions at the same time
11
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
12
what is the purpose of the CPU
- To fetch and execute program instructions stored in memory.
- often referred to as Von Neumann architecture
13
name all four different types of registers in the CPU
- program counter
- MDR (memory data register)
- accumulator
- MAR (memory access register)
14
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
15
what is the function of the MDR (memory data register)
- temporary store for anything copied from memory
16
what is the function of the accumulator (register)
- stores the results of calculations carried out by the ALU
17
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
18
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
19
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
20
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
21
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
22
ADDRESS BUS
used to retrieve the location of the data where the CPU must read/ write to
23
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
-
24
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
-
25
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
-
26
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:
-
27
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
28
what is open source software
-Free software that users can download.
-Source code is available to users
29
what is the difference btwn pop and imap protocol
POP = Emails downloaded on to device
IMAP = Emails stored on a server
30
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
31
what are the TCP/IP layers for sending data
-Application
-Transport
-Internet
-Link
32
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
33
what is FTP protocol
-File Transfer Protocol
-Rules for file transfer
-Used to transfer files too large to beattached to an email
34
What is SMTP
-Simple Mail Transfer Protocol
-Rules for sending Emails
-Goes from client to different servers until it reaches its destinantion
35
What is IMAP
-Internet Message Access Protocol
-Emails stored on server
-Can be read from any device
36
What is HTTP protocol?
-Hyper Text Transfer Protocol
-Rules for web browser and server when requesting and supplying information
37
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
38
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
39
What are switches?
-Reads MAC address
-Sends only to recipient
-Big and expensive
40
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
41
What is a MAC address?
-NIC's Media Address Control (MAC)
-Ensures data directed to correct computer
42
What is an internet layer protocol example?
IP
43
What are link layer protocol examples?
Ethernet/Wifi Protocols
44
What's a router?
-Connects networks
-Reads address info
-Transfers data between home network and internet
45
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
46
Cable networks pros and cons (One computer)
-High bandwidth
-More secure (Just needs a plug)
-No interference
>Installation difficult
>Poor mobility
>expensive
47
Pros/Cons Open source software
-Free to use
-Users can change software
-Source code can be studied
>Needs specialist knowledge
48
What's POP protocol?
-Post Office Protocol
-Mail downloaded from server when there is a connection
49
What is a HUB?
-Doesn't check address(Sends info to everyone)
-Causes unnecessary network traffic
-Cheap and small
50
Wireless Pros and cons
-Easy to install
-Cheap
-Mobile
>lower bandwidth
>Needs security passwords
>Signals can be interfered by walls
51
Why is Fibreoptic better than copper?
Faster and travels over longer distances
52
What sort of waves does wireless use?
Radio waves
53
what are high level programming languages
- similar to natural human language
- it uses key words ie 'print', 'if', and 'then'.
- Programs written in high-level language have to be translated into machine code to operate
54
what type of memory stores a computers start up programs
ROM
55
what software is used to imitate a real life situation
simulation software
56
what component of the CPU holds the current program instruction
register
57
describe the concept of a stored program
when a computer stores program insturctions in its electronic memory
58
what are the 3 functions of an operating system
- manages the memory (many programs request data to be loaded)
- allocates CPU time to different applications (the require the CPU to execute program instructions)
- provides the interface btwn a user and computer system
59
what is the organisation you must pay to access the internet
internet service provider
60
describe the topology of a star network
- all nodes are individually connected to a central connection point, like a hub or a switch
- they are not connected to each other
61
describe the role of a wireless access point on a network
- they convert data received through cables into wireless signals and vice versa
- directs messages to all devices
62
describe the role of a router on a network
- it transfers data btwn the internet and a home network
- reads address info & forward messages to the correct network
63
explain the effects of using the JPEG compression format for images
- it's an example of lossy compression so this deletes data
- it has been irreversibly changed as the data cannot be restored
64
24 bit images must be displayed on a screen at a resolution of 400 x 250 pixels
contruct an expression to calculate the size of one of the image files (KB)
(24 x 400 x 250) / (8 x 1024)
65
24 bit images must be displayed on a screen at a resolution of 400 x 250 pixels
convert BB4A0F into binary
-
66
why is hexadecimal easier than binary when specifying screen colours
- its easier to remember and easier to enter 6 digits than 24 digits so less human error and less storage space
67
identify a binary system used to represent text
ASCII
68
explain the concept of overflow in relation to binary notation
- when a calculation is performed by the computer & the result is greater than the computer can handle/represent (more than 8 bits)
69
describe the result of carrying out an arithmetic shift right one place to an 8 bit binary integer
-
70
AADACCEGEHABE
explain why run-length encoding algorithm may not be appropriate for encoding this image
-
71
desbribe the difference btwn structured and unstructured data
> Structured data is data arranged in an organised, defined way and is easier for a computer to process because data is arranged in a standard, precise layout.
> Easy to work with
> Unstructured data has no set way for a computer to interact with it and cannot be easily mapped by a computer into pre-defined fields.
> not that easy to work with.
> An epitome of structured data is the database.
72
define Malware
– software that has been designed to gain unauthorised access to a computer system in order to disrupt its functioning/ to collect information
73
define Spyware
- software that spies on users by sending screenshots/ key presses to the hackers computer, revealing passwords
– often comes packaged with other software ie free software, the user not knowing they're installing it.
74
define Virus
– computer program hidden in another program, usually having a harmful effect ie corrupting/ deleting data on a disc.
- Can replicate & insert itself into other programs/ files which can be passed on
75
what are High level languages
Programming languages that resemble human languages.
They use key words such as print, if and then.
- they address the programming logic rather than dealing with hardware issue such as memory addressing.
- Most programs are written in high level languages
76
what does Antivirus software do
– checks all files that're loaded onto a computer for viruses. Can be set to carry out routine scans & viruses in emails
77
what does Antispyware software do
– checks for and blocks spyware
78
how do antimalware check for malware
- They scan for malware using a database of known malware definitions (signatures), constantly being updated
- Some use a form of analysis called HEURISTICS
these use a set of rules to detect malicious behaviour by analysing the programs/files behaviour.
79
what does File conversion software do
– converts one type of file format to another so it can be used by another program ie text/ spreadsheet/ database files.
- useful for media files ie images/videos where there're different file formats (AVI/MP4/FLV)
80
what does File repair software do
– type of data recovery software that can repair corrupted files, that could've been corrupted by malware or a computer malfunction
81
what happens in the fetch cycle of the fetch-decode-execute cycle
- the CU sends a 'read' signal to the RAM on the control bus.
- the CU uses the address bus to send signals specifying the required memory location in the RAM.
- this data is transferred to the CPU along the data bus
82
what happens in the decode and execute cycles of the fetch-decode-execute cycle
instructions and interpreted and carried out:
- program instructions/ data is sent to the CU from the RAM
- the CU decodes the instruction then executes it. if a calculation needs to be performed it instructs the ALU
- calculations are carried out by the ALU
83
state what is done briefly at each stage of the fetch-decode-execute cycle
- fetch: the next institution to be executed is transferred from the RAM to the CPU
- decode: the CU interprets the institution
- execute: the CU then carries out the instruction and instructs the ALU if calculations need to be performed
84
define secondary storage and give examples of secondary storage devices
- any non volatile storage device that is internal or external to the computer
- ie USB flash drives or floppy disks
85
how is data stored on Magnetic storage devices
give an example
- Data is encoded as opposing magnetic polarities on the surface of the disc by electromagnets in the read/write heads
- The disc spin & reads/writes heads move across the discs
- ie hard disc drives which consist of stacks of non-removable discs coated with magnetic materials
86
why are secondary storage devices needed
- unlike RAM that is volatile, secondary storage doesnt lose its data when there's no power
-meaning it provides permanent storage for programs/data that would otherwise be lost when the computer is stitched off
- Ie USB flash drive
87
name all three types of storage device
magnetic discs
optical disks
solid state (flash) memory
MOSS
88
how is data from secondary storage devices processed
- data is stored permanently on secondary storage devices but the CPU cannot access them directly
- they are therefore transferred to the main memory
89
how is data stored on Optical storage devices
- Digital data is stored along the track by etching PITS onto the surface of the disc
- When the light from a laser hits the LANDS it is reflected back to a detector but is scattered away by the pit & no light is detected. The two events are represented by '1' and '0'
90
how is data written to a recordable CD-R (optical storage)
- the discs surface covered by a translucent dye so light passes through
- data is written to the disc by a powerful laser burning the dye creating black spots that dont reflect light
- the reflecting areas are interpreted as 1s and black spots as 0s
91
what is cloud storage
OFFSITE storage (not on a company's premises – elsewhere in the world) made available to users over a NETWORK, usually the internet
92
compare backing up data to a magnetic hard disc with an optical disc
- hard disc drives magnetically store data by electromagnets in read-write heads encoding data as opposing magnetic polarities on the surface of the discs
- when data is written to a CD-R a powerful laser light burn the light on the surfaces creating black spots that dont reflect laser light. the area that reflect and do not reflect are interpreted as the digits 1s and 0s
93
how does multitasking work on a computer with a single core processor
- multitasking is the process where programs appear to run concurrently
- but in fact the OS is sharing out CPU time btwn each task so in turn they can be processed
- the CPU switches between the tasks and priorities them so some have more CPU time than others
94
how is memory managed in a computer
- the OS prioritises tasks and allocates time slot to each process
- checks all requests for memory are valid and allocates it accordingly
- swaps out data to the virtual memory when the main memory is full
95
list the advantages of using a flash memory device rather than a magnetic disc drive for data storage
- faster access
- quiter
- lighter & more portable
- solid state (more portable)
- less easily damaged
- less likely to lose data
96
state the disadvantages of using flash memory
- more expensive than magnetic storage (price per GB)
- maximum storage capacity available is lower than by modern magnetic disc drives
- has a shorter life span than hard disc drives
97
explain how each secondary storage device physically records data:
magnetic hard drive
flash memory USB stick
optical disc drive
- hard disc drives use electromagnetism to store data magnetically on metal discs
- flash memory USB sticks use electricity to change the state
- DVDs use light produced by a laser to store data on the disc by changing its surface
98
what are the uses of flash memory (give examples)
- solid-state drives (SSDs) provide secondary storage instead of magnetic storage
- secure digital (SD) cards are used in portable devices ie phones and cameras
- USB flash drives are convenient compact forms of flash memory for sharing & transferring data
99
what is the function of systems software
Utility software on a computer is a set of tools that can be used to analyse and optimise efficiency
100
-
Application software
It is an end user program
Also called applications, and user programs perform user-identified tasks such as word processing & photo editing or are used for entertainment such as games viewing videos
Memory management
In a computer system many programs will be running at the same time, called multitasking
Although programs appear the run at the same time the OS is sharing out processor time between them so that into turn they can have their program instruction processed
These activities that're being performed are called processes
Some processes are visible to the user as application software but many aren't seen by the user
There are usually programs & processes that the user cannot see running in the background
All processes require the use of the CPU and memory
The OS prioritises the tasks & allocates time to each process
It checks that all requests for memory and valid& allocates it accordingly
It then swaps out data to the virtual memory when the main memory is full
File management
The OS creates a folder & file structure for data, making it easier for users to organise/ find data in a systematic way
On networks/ shared computers file management is used to control file permissions
File permissions control who can delete the file. It is the OS that asks for confirmation when you try to delete a file
101
how do computers carry out logical operations on data and display it to the user
using the input-process-output model
102
name some input devices
keyboard
mouse
microphone
webcam
103
name some output devices
monitor
speakers
printer
104
describe what is meant by the input-process-output model
- data is entered into the computer and is manipulated according to the instructions of the program
- the results of the processing are then displayed to the user in a suitable form
105
a user has to log in to a network. describe this in terms of the input-process-output model
input: the user inputs their login info through a keyboard which is an input device
processing: the login name and password are processed by the computer and the CPU validates it by comparing it with data stored on the hard drive
output :if the login is unsuccessful and the data doesnt match that stored, a message will appear asking them to enter it again through the monitor which is a output device
106
a user has to log in to a network. describe this in terms of the input-process-output model
- input: the user inputs their login info through a keyboard which is an input device
- processing: the login name and password are processed by the computer and the CPU validates it by comparing it with data stored on the hard drive
- output :if the login is unsuccessful and the data doesnt match that stored, a message will appear asking them to enter it again through the monitor which is a output device
107
list 2 registers of the CPU with specific functions in the fetch decode execute cycle
program counter
memory address register
108
describe the role of the control unit in the operation of the CPU
coordinates the actions of the other components in the CPU and the whole computer by sending out control signals
- it also decodes the program instructions and executes them using the other components
109
explain how program instructions stored in computer memory are processed by the CPU
- during the fetch phase of the fetch decode execute cycle the CPU sends a signal to the main computer memory requesting the next instruction to be executed
- this instruction is decoded by the CPU and executed
if calculations are required these are carried out by the ALU
110
state the type of memory used to store application data during execution
- ROM
111
state an advantage and disadvantage of RAM
+ data can be read from and written to RAM
-RAM is volatile so if you turn the power off data in RAM is lost
112
what is ROM
- used to sore instructions that dont nee to be changed during normal use
113
state an advantage and disadvantage of ROM
+ ROM is non volatil so it retains data even when the power is turned off
- data can only be read from ROM
114
state an advantage and disadvantage of ROM
+ ROM is non volatil so it retains data even when the power is turned off
- data can only be read from ROM
115
give 2 differences between RAM and ROM
-
116
what is cache memory
- very fast memory, usually within the CPU
- speeds up processing by storing recently/ frequently used instructions so they don't have to me fetched from the main memory
117
describe the role of programs stored in ROM
-
118
describe the diference between volatile and non volatile memory
-
119