Computing science.

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  • Created by: anna_19
  • Created on: 24-08-15 17:53
What is a computer system?
A collection of hardware and software that works together to achieve some data processing tasks.
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What are general purpose (computer) systems?
Personal computers such as smart phones are designed to perform multiple tasks.
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What are dedicated systems?
Specially produced to perform a single function or set of functions.
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What are control systems?
Computer systems that control machinery, rather than produce output for humans to read or respond to.
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What are embedded systems?
Computer systems that are part of a larger system.
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What are expert systems?
Computer systems designed to behave like a human expert.
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What are management information systems?
They bring together the information from all parts of an organisation so that managers can make sensible decisions.
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What are standards or what do they refer to?
They refer to convections and rules.
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There are various categories of standards, what do standards exist for?
Programming languages, operating systems, data formats, communications protocols & electrical interfaces.
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What are proprietary standards?
They are owned by an organisation. They ensure compatibility between the company's products.
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What are industry standards?
They are set by recognised non-commercial organisations.
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What are open standards?
They are publicly available and has various rights to use associated with it.
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What is hardware?
The physical components of a computer system.
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What is the CPU?
The central processing unit carries out all the processing in a computer.
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What does the (ALU) arithmetic and logic unit?
It carries out all of the arithmetic and logical operations.
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How does the CPU work?
It fetched the instructions from memory then decodes the information to find out what processing to do and final it executes the information. Fetch, decode & execute.
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What is the boot sequence?
A sequence of processes that contains all the information and instructions to get the computer up and running.
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What is the CPU clock speed?
The speed of the fetch-execute cycle is determined by an electronic clock chip.
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What are multiple processor cores?
They use multiple CPU's working together.
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What is the RAM?
The random access memory is the memory stored on the computer yet it goes when its turned off. It can be accessed and changed by the compute at any time. It stores programs and data being used by the computer. It contains the operating systems.
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What is the ROM?
The read only memory is the memory stored on a computer which will stay there all the time even when the computer is switched off. It is programmed during computer manufacture. It stores instructions and data required to start up the computer.
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What is virtual memory?
The operating system then swap jobs in and out of memory using virtual memory. Part of the hard drive used as an extension to RAM.It is used when the computer does not have enough RAM to hold all the data and programs required.
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What is flash memory?
A type of ROM that can be rewritten. It is used as a portable medium for storing and transferring data.
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What are input devices?
A way to get information into the computer.
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What are output devices?
A way to get information out of the computer.
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Give at least 5 examples of input devices.
Keyboard, mouse, touch screen, microphone, camera, bar code scanner, sensor, eye typer, foot mouse, puff **** switch, braille keyboard.
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Give at least 5 examples of output devices.
Monitor (LED screen/ LCD monitors, touchscreen.), printer (monochrome or clour laser printer, inkjet printer, 3D printers, thermal printers.), speakers (music, warning sounds, voice communictaions.), actuators,
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What is a magnetic hard disk used for?
A magnetic hard disk stores the operating hard disk stores the operating system, installed programs and user data.
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What is a optical disk used for?
An optical disk is excellent for transferring files or distributing software.
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What is software?
The various kinds of programs used to operate computers and the data that is used by the programs.
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What does application software handle?
The real-world jobs that users want to do.
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What is the utility software used to maintain?
It is used to maintain computer systems.
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How is software usually produced?
Using programming language.
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What is system software?
The software that controls the hardware.
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What is user interface software?
An operating system must provide a way for a user to control and interact with the computer. The user interface is the boundary between the human user and the machine.
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What is a file?
A named store of data on a secondary storage medium.
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What is defragmentation?
A process which can be used to tidy up the disk or other medium so that the parts of the files are moved to be stored next to each other.
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What is multiprogramming?
Most all-purpoe systems commonly have several programs loaded into memory at the same time.
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What is multitasking?
In many cases, it seems to the user that the processes are running at the same time.
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A multiprogramming operating system must:
1) make sure that the CPU is in use as mjch of the time as possible. 2) try to speed up the operation of all tasks. 3) share resources fairly between tasks.
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What is a directory?
A logical grouping of files.
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What are attributes?
Extra information about the file like creator, date it was last accessed, date it was last changed...
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Software can be obtained from ...
...various sources.
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What is custom written software?
Software specially comissioned fro a particular customer.
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What is off the shelf software?
It can be brought from a supplier already boxed up and ready to install.
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What is open source software?
Software that has been placed in the public domain by the programmers.
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What is proprietary software?
Software that is developed for profit by a company, users must buy a license to use it.
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4 bits =
1 nibble
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8 bits =
1 byte
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1024 bytes =
1 kilbyte
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1024 kilbytes =
1 megabyte
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1024 megabytes =
1 gigabyte
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1024 gigabytes =
1 terabyte
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Hexadecimals =
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A = 10, B = 11, C = 12, D = 13, E = 14, F = 15.
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What is metadata?
Data about the data.
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What is a pixel?
One 'dot' in the image.
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1 bit can represent how many colours in a picture?
2 colours = black and white.
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2 bits can represent=
4 colours.
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8 bits can represent=
256 colours.
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16 bits can represent=
65 536 colours.
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The more bits per pixel (bpp) the greater the ...
... colour depth and the more bits we need to store the data.
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16 bpp=
high colour
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24 bpp=
true colour
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What is the resolution?
The number of pixels per unit.
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How are sound files described?
By metadata to make sure the computer can interpret the data accurately.
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What is the bit rate?
The amount of space used for each sample.
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What is a accumulator?
A special register in the CPU used to store the results of any calculation.
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What is a database?
A persistent organised store of data on a computer system.
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What must databases need to be?
1)accurate, 2) up to date, 3) available to those who nee to use them, 4) protected from those who should not have access.
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Data can be lost because of:
1)a catastrophen like a fire, 2)an accident like an employee deleting data, 3)malicious action like an intruder.
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What is data integrity?
Data reflects reality.It implies that the data is correct and fit for purpose.
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What is validation?
The process of checking data when it is input.
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What is verification?
Checking that the data entered is correct.
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Wat is a view?
A subset of the data in a database.
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What is data matching?
It compares different databases to look for particular relationships.
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What is data mining?
A process that looks in many different unrelated databases.
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What is data redundancy?
Unnecessary repetition of data.
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What is an entity?
Something in real life about which we store data.
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What is a transaction?
When a change takes place in a database.
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What are reports?
Reports are output from a database.
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What are queries?
A query is used to extract a subset of the data in a dataase.
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What is a database module?
A unit of software that takes care of some particular funcitionality of a database.
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What is a network?
A collection of connected computer plus their peripherials. Each device on a network is called a node.
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What is a LAN?
A local area network,a computer network that interconnects computers within a limited area such as a residence, school, laboratory, or office building.
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What is a WAN?
A wide area network, a telecommunications network or computer network that extends over a large geographical distance.
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What is a network hardware?
Special hardware is needed to connect computers.
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What is a NIC?
Each device on a network needs a network interface controller/cards (calso known as a LAN adapter)
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Most LANs make use of a network standard called...
...Ethernet.
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Every NIC has a unique number stored in ROM. This is called...
...its MAC (media access control) address. Thi allows each device on a network to be identified.
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What are cables?
The connections between devices on most LANs are made with copper cable.
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What are hubs?
These are hardware devices that connect many network devices together, making them into a single network segment (a segment is defined part of a network.)
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What are switches?
Switches connect network segments or devices. They can also act as bridges, which connect more than one network, allowing them to function as one network.
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How does a switch differ from a hub?
By transmitting a message only to the device intended instead of to all connections.
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What is a router?
A router recieves data in the form of packets and forwards them to their destination which is often another router.
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What is a client-server network?
Client-server is by far the most common way to set up a network. One or more servers provide services to many client machines where the users work.
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What is peer- to- peer network?
All computers are equal. Each computer serves the needs of the user as well as carrying out networking functions.
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What is a network topology?
A description of the arrangement of a network, including its devices on the network and connecting lines.
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What is a bus topology?
The computers are attached to a single backbone. A terminator is attached at each end to prevent reflection of signals. Signals travel in either direction.
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What is a star topology?
Client machines are connectes to a central switch or hub, which is usually in turn connected to one or more servers. Signals travel in either direction.
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What is a ring topolgy?
Data passes through each device in the network, carried in data units called tokens. Traffic is one-way which prevents collisions.
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What is a protocol?
A set of rules that covers data communications.
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What are TCP/IP?
Transmission Control Protocol/ Internet Protcol is various protocols exist, but the most widely adopted is a set of protocols.
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What is a MAC address?
A unique number stored in each NIC so it can be used to identify a device on a network.
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The internet is a means of connecting...
...millions of computers and computer networks acreoss the world.
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The internet makes use of ...
...IP addressing to identify connected resources.
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What is HTML?
Hypertext Markup Language, this is a way of using text files in order to describe a web page. It uses tages to instruct a browser how to interpret and display items on a web page.
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What is file compression?
Reducing the size of a file (saves stroage space and reduces transmission times on a network)
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What is lossy compression?
Every single bit of data that was originally in the file remains after the file is uncompressed.
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Lossy compression is used in file formats such as...
...MP3, JPG, MPEG.
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The more an image is compressed,...
...the less detail will be visible.
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What is lossless compression?
Reduces a file by permanently eliminating certain information, especially redundant information.
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Card 2

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What are general purpose (computer) systems?

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Personal computers such as smart phones are designed to perform multiple tasks.

Card 3

Front

What are dedicated systems?

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Preview of the front of card 3

Card 4

Front

What are control systems?

Back

Preview of the front of card 4

Card 5

Front

What are embedded systems?

Back

Preview of the front of card 5
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