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GCSE COMPUTER SCIENCE > 8525 Unit 4 > Flashcards

8525 Unit 4 Flashcards

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1
Q

Examples of hardware

A

Input devices:
Keyboard
Mouse
Trackpad
Microphone

Output devices:
Display
printer
Speakers

Storage devices:
Hard drive
CD/DVD/Blu-ray drive
SD cards
Flash media

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2
Q

Definition of hardware

A

Hardware are the physical components that make up a computer system, including input/output/storage devices, the CPU and RAM

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3
Q

Examples of software

A

Offic suite
Operating system
Computer games
Web browser
Email client
Photo editing software

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4
Q

Software definition

A

The non physical programs that are stored by and run on a computer system

Software makes use of physical hardware components and devices as the way of:
- taking inputs from users
- outputting information to users
- storing information

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5
Q

System software

A

The software that provides a platform for other software to work, including OS and utility programs

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6
Q

Operating system examples

A

Microsoft
Google
Apple

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7
Q

What does an operating system do

A

MANAGE computer hardware, users and the resources used by software

Responsible for MANAGING:
Processors
Memory
Input/output devices
Applications
Security

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8
Q

What does an operating system do: processors

A

Programs are run by one or more processors
A single processor can have a number of cores
Each core is essentially another processor
The operating system is responsible for deciding which program will run on the processor and how much time it will get to run

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9
Q

What does an operating system do: memory management

A

To run a program, the computer must copy the program from storage into main memory
The operating system keeps a record of where each program and its data are located and will make sure not to overwrite existing data

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10
Q

What does an operating system do: input/output devices

A

OS manages getting inputs from and sending outputs to peripheral devices (mice, keyboard, printers, displays, digital cameras, graphics tablets)

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11
Q

What does an operating system do: device drivers

A

Device driver is a program that controls peripheral devices
Each device uses its driver to communicate with the OS

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12
Q

What does an operating system do: sending data to a printer

A

Computer sends data to printer
Data is sent to a print queue
Data in print queue is transmitted to the printer
Printer will send its status back to OS, e.g out of paper (hardware interrupt)

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13
Q

What does an operating system do: application management

A

E.g web browsers, music and video players, PDF viewers, email clients and instant messaging software

The OS provides graphical user interface—windows, minimise, maximise, resize

OS copies the program into RAM and allocates an area of the RAM for the program to use when a new application is opened

Likewise the OS makes sure that the application’s program is removed from the RAM when it is closed

OS responsible for install and updating applications

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14
Q

What does an operating system do: security management

A

User management—sorts all users and their passwords in a file/database

Access rights to files, programs and services:
computer used by more than one person—each user only allowed to see their own files
Users and system administrators have different levels of access rights
Some users allowed to read but not edit files

Encryption: hard drives and removable media

Memory protection: prevents programs being able to view/overwrite other programs’ data stored in RAM

Security updates—automatically downloaded and installed

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15
Q

Utility software

A

Keeps OS working well—perform extra functionality and housekeeping tasks that keep computers running efficiently
Includes:
Encryption software
Defragmentation software
Data compression
Disk clean-up tools
Disk formatters
Anti-virus software

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16
Q

Utility software: encryption software

A
  • organisations use email encryption:
    • Accountants discussing financial information of companies
    • Sharing confidential internal files
  • Encrypt entire hard disks
  • Encrypt files and folders on a portable disk, eg. USB removable storage
  • Encrypt communication with Eb sites
  • Encrypt data in an organisation’s database—sensitive data—passwords
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17
Q

Utility software: defragmentation software

A
  • read times are far faster
  • Free space is also in one place so new files do not need to be fragmented
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18
Q

Why is defragmentation good

A

When a file is ‘fragmented’:
In order to read the file, the drive head will need to move to more locations
This makes it far slower to access files and programs

Defragmenting the hard disk reorganises files so they are stored together:
Read times are far faster
Free space is also in one place so new files do not need to be fragmented

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19
Q

Utility software: data compression software

A

Utilities such as WinZip enable users to compress and decompress files or folders:

Reduces the amount of storage space needed on a disk
If sending the files, it reduces the amount of data that is sent
Compression may allow attachments to be sent via email that would otherwise have been larger than a file-size limit
More data can be stored on backup media

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20
Q

Embedded systems

A

embedded computer is a single microprocessor that includes RAM, ROM and a CPU

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21
Q

Embedded systems examples:

A

Washing machine
Interior light in a car
MP3 players
Digital watches
Calculators

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22
Q

Embedded vs non embedded:
CPU speed
Software
Storage
Reliability

A

Embedded:
Typically slow
Has one purpose and cannot install new software
Programs stored on ROM
Typically very reliable—e.g a microwave should not have a bug that changes defrost to full power

Non-embedded:
Typically very fast
New software can be installed
Programs stored on hard drives
As it runs many software programs it may be less reliable and need restarting the device

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23
Q

High level programming languages

A

Python, Visual Basic, C#, Java, C++, PHP, Delphi, Logo

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24
Q

Query languages

A

SQL

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25
Q

Markup languages

A

HTML, XML

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26
Q

Low level programming languages

A

Assembly language

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27
Q

Machine code vs assembly

A

Machine: written all in binary—difficult and time consuming

Assembly language: creates programs more easily

28
Q

Machine code and processors

A

Processors can only execute instructions in machine code

29
Q

Assembly languages

A
  • processor-specific
  • Has to be translated into machine code before it can be executed
  • Used for software in embedded systems, e.g washing machine, used to control specific hardware components, e.g. device drivers
30
Q

High level vs low level

A
  • high level
    • easy to learn
    • Programs written faster
    • Easier to understand and debug
    • Need to by translated into machine code in order to run
  • Low level
    • Runs very quickly
    • Requires less RAM
    • Used to control and manipulate specific hardware components
31
Q

Assembly language uses

A

Allows the programmer to precisely control any instruction on the processor
Means that programs can be made to be very efficient
For instance, when a graphics device driver is programmed to run quickly and make use of all the advance features

32
Q

High level languages explain

A

Must be translated into machine code in order to run
A single statement usually translates into several machine code instructions
Translation is done by a program which may be either a compiler or an interpreter

33
Q

Translators

A

Compiler
Interpreter
Assembler

34
Q

Translators: compiler

A
  • translates high level into machine code
  • Machine code produced can be saved on a storage device and run whenever required
35
Q

Translators: interpreter

A
  • translates high level into machine code
  • No object code is produced
  • Executes immediately
  • If it reaches a line with syntax error it stops and displays an error message
36
Q

Translators: assembler

A

Assembly code to machine

37
Q

Interpreter vs compiler vs assembler
Input
Output
How it works
Speed of execution
What end users need to run program
Source code

A

Interpreter:
High level language
No output—program runs straight away
Translates source code and immediately runs it
Slow as needs to be translated each time it is run
Each end user needs the interpreter and the program
End user can see the source code

Compiler:
A high level language
Machine code
Compile source code so it can be run later
Fast as it just runs the machine code
Users need just the compiled program
End user can’t see the source code

Assembler:
Assembly language
Machine code
Assemble source code so it can’t e run later
Fast as it just runs the machine code
Users need just the compiled program
End user can’t see the source code

38
Q

The main components of a computer

A

Main memory—RAM, ROM
Input devices—microphone, keyboard, keyboard
Secondary storage—CD, SSD, HD,DVD
Output devices—printer, screen, scanner

39
Q

CPU

A

Runs instructions of a program
Runs one instruction at a time
Carries out billions of instructions per second
Von Neumann architecture
Control unit
Arithmetic-logic unit (ALU)
Registers
Clock
Buses

40
Q

Von Neumann architecture

A

Program instructions and the data the programs are using are both stored in the same memory

The CPU accesses both instructions and data from the same RAM

41
Q

Control unit

A
  • coodinates and controls all of the activities taking place within the CPU
  • Decodes instructions and executes them
  • Receives signals from the system clock
  • Directs the timing and control of other parts of the CPU
42
Q

Registers

A

Carries out operations

A register is a very fast memory location in the CPU
Small memory
Stores a piece of information for a short time

43
Q

Arithmeric logic unit (ALU)

A

Arithmetic operations: addition, subtraction, multiplication, division

Logical operations: comparing one data item to another

44
Q

Clock (cs)

A
  • controls the timing of the processor
  • A faster clock speed will result in the faster processing of instructions
45
Q

Buses (cs)

A
  • A bus is a set of parallel wires connecting two or more components of the computer
  • address busStores the address of the memory or device controller to be read from or written toOne way only bus
  • Data busCarries data throughout the computer system
  • Control busUses control signals to control all activities within CPU
46
Q

What affects CPU performance

A

Clock speed—cycles per second measured in hertz

Number of cores—the number of duplicate processing units placed in one CPU

Cache size—memory on the CPU that is faster than RAM but slower than registers

47
Q

Multi-core processors

A

A dual-core processor has two processors in the same integrated circuit, linked together

  • a dual core processor has the potential to perform tow instructions at the same time
  • allows twice as many instructions to be executed, but doesn’t always perform at this rate as software may not be able to take full advantage of both cores
48
Q

Effector on speed of cache

A

Ram = relatively slow memory to access—further ways form the processor than cache
Takes longer to retrieve an instruction/data from RAM than cache

Program instructions and data that are fetched are stored in cache in case they are needed again soon

49
Q

Fetch decode execute cycle

A

Instructions are placed in RAM
The next instruction is fetched
It is decoded by the CU
The CU tells the relevant components to execute the instruction

50
Q

RAM random access memory

A

Main memory
Can be read from and written to
Access to RAM is much faster than a hard drive
Will normally store:
OS currently in use
Software currently in use
Data which the software is using
When computer is turned off, data in RAM is lost—RAM is volatile
All programs and data are stored permanently on non-volatile storage

51
Q

ROM read-only memory

A

Permanently holds data
Data is read from ROM, but cannot be written to it
Non-volatile
Stores:
Initial program that is run when the computer is turned on—the bootstrap
Tells the computer where it will find the operating system on the hard drive
Stores the basic input/output system (BIOS)
BIOS can run without a hard drive/other secondary storage
Controls basic technical configuration of the computer such as the processor speed and system time

52
Q

RAM vs ROM
Size
Used to store
Read ability
Write ability
Volatile

A

RAM:
Typically 4GB - 32GB
Running programs and operating system
Yes
Yes
Yes

ROM:
Typically 4MB - 8MB
BIOS and bootstrap
Yes
No
No

53
Q

Memory speed

A

The speed that data can’t e accessed changes through the different components in a computer

54
Q

Secondary storage

A

Non volatile

DVD
Cd
Tape drive
SD
Hard drive

55
Q

Memory vs secondary storage

A

Main memory Secondary storage

Volatile (RAM) Non-volatile

Very fast to read/write Slow to read/write

Expensive per GB Cheap per GB

Stores data and programs currently Permanently stores data to be used
in use by the computer system

Directly accessible by CPU Not directly accessible by CPU

56
Q

Storage methods of secondary storage

A

Magnetic
Optical
Solid state

57
Q

Storage methods of secondary storage: magnetic

A

Mechanical parts move over the disks surface to read and write data magnetically, or a drive head reads a magnetic tape

58
Q

Storage methods of secondary storage: optical

A

Lasers read and write data using light

59
Q

Storage methods of secondary storage: solid state

A

Data is recorded onto solid memory chips without any moving parts

60
Q

Magnetic storage advantages, disadvantages, uses, capacity

A

Advantages:
Cheap, large storage capacities, relatively fast write speed

Disadvantages:
Lots of mechanical parts, durability and issue, sealed unit due to disk head and platter precision and not very portable

Uses:
Personal computers, storage of large quantities of data

Capacity:
500GB - 12 TB

61
Q

Optical storage advantages, disadvantages, uses, capacity

A

Advantages:
• Cheap, very easily portable, takes up little space physically

Disadvantages:
• Less storage capacity compared to other types
• Easily damaged / scratched, requires a CD reader
• Slow write speeds

Uses:
• Songs, videos and other multi-media storage, backup and archiving of data

Capacity:
• CD-ROM - up to 720 MB
• DVD - up to 8.4 GB (dual layered disk)
• Blu-Ray- up to 50 GB (dual layered disk)

62
Q

Solid state drives basic features

A

Solid-state drives use non-volatile flash memory to store information
• Very fast read/write speeds as it doesn’t need to wait for a disk to spin to the correct location and an arm to move
• No mechanical or moving parts meaning these disks are very durable

63
Q

SSDs advantages, disadvantages, uses, capacity

A

Advantages:
• Highly durable, no moving parts, very fast read/write speeds, no noisy fan or drive arm, faster start up times

Disadvantages:
• More expensive than magnetic hard disks, similar storage capacity as magnetic disks

Uses:
• Higher end computers
• Laptops
• Smartphones and tablets

Capacity:
• 100GB - 16TB

64
Q

Flash memory

A

Low cost
Potable
No moving parts
Durable

65
Q

Cloud storage

A

Refers to saving data in an off-site storage system maintained by a third party, e.g Dropbox, Google drive

Data that is stored on cloud storage can be located anywhere in the world

66
Q

Cloud storage advantages

A

Easy to use, most companies offer apps for desktop and mobile devices to manage their data
Companies offer a high data storage capacity
Convenient to use, users can access data from anywhere with an internet connection
Backups are carried out by the cloud provider so save the need for local backups
The data storage capacity can be increased easily as users need more

67
Q

Cloud storage disadvantages

A

Data cannot be accessed without and internet connection
A company needs to trust that the security of the cloud service is enough to stop a data breach—they won’t be directly able to control the security of the data
Uploading and downloading data could take a long time and is dependant on the available bandwidth of the user’s connection

GCSE COMPUTER SCIENCE (4 decks)

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