Computer Science Flashcards

1
Q

what is a computer?

the definition

A

A computer is a machine that processes data.

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2
Q

what is hardware?

definition

A

The physical parts of a computer.

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3
Q

What parts of a computer does hardware involve?

examples

A

Internal parts:

  • Motherboard
  • CPU

External devices:

  • keyboard
  • screen
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4
Q

What is software?

definition

A

The programs that run on a computer.

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5
Q

How many main categories of software are there and what are they called?

A

There are 2 main categories.

  • System software
  • Application Software (apps)
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6
Q

What is system software?

definitions

A

Programs that are needed for the computer to function. (Includes the operating system)

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7
Q

What is the application software (apps)?

definition

A

Programs that enable a user to perform a specific task.

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8
Q

What does a computer need in order to function?

2 main things

A

hardware and software

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9
Q

what is an embedded system?

definition

A

An embedded system is a computer that is built into another device to control it.

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10
Q

What are examples of embedded systems?

AND

What is the purpose of the embedded system in the example?

A
  • washing machine
    Controls release of soap and water. Controls heater to heat water to a chosen temperature. Spins drum motor at a chosen speed for a set amount of time.
  • microwave
    Controls the temperature/ heat to keep it the same level as the user selected
  • Vending machine
    controls the release of contents / items. controls payment.
  • traffic lights
    controls coloured lights shown to symbolise when traffic should stop.
  • lifts
    controls the movement of the lift - whether it goes up or down to different floors due to the input of the user.
  • smart meter
    Measures amount of energy used.
  • Auto pilot
    controls altitude and direction depending on the input given by the user.
  • sat nav
    locates and uses satellites to find your location and controls where your pin point location is on the device. Controls where the line of travel shown goes depending on your destination.
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11
Q

What does CPU stand for?

AND

what is it like?
(ie if it was the human body, what would the CPU be?)

A

The central processing unit

it is like the “brain” of the computer

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12
Q

What is the CPU?

definition

A

The CPU is a microchip that sits in the middle of the motherboard and carries out (processes) instructions stored in memory by fetching them, decoding them and executing them one at a time.

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13
Q

What is CPU architecture?

A

the main components (internal parts) of the CPU and how they interact with each other.

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14
Q

who’s design is what most modern CPU’s are based on?

BONUS:

  • what was his profession?
  • when did he come up with the design? (year)
A

John Von Neumann

BONUS info:
he was a mathematician and came up with the design in 1945

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15
Q

how many main internal components in the CPU are there?

BONUS:
what are they?

A
1- the control unit
2- the clock
3- The arithmetic logic unit (ALU)
4 - registers
5- Buses
6- cache memory
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16
Q

what is the control unit?

definition

A

In the CPU

fetches instructions from memory. and decodes them one at a time. It also controls the flow of data between the parts of the CPU, main memory and input/output devices.

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17
Q

what is the clock?

definition

A

In the CPU

The clock synchronises all parts of the CPU by sending electronic pulses at a constant rate. The number of clock “ticks” per second is called the clock speed and is measured in Hertz.

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18
Q

What is the arithmetic logic unit?

definition

A

In the CPU

The ALU carries out arithmetic calculations such as addition, subtraction and binary shifts. It can also do logical comparisons such as “greater than”, “less than”, AND, OR and NOT.

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19
Q

What are the registers called and are?

definitions and what they are

A

In the CPU.

Registers are small pieces of internal memory which hold instructions, data or memory addresses that are currently being used by the CPU.

  • program counter
  • MAR (memory address registers)
  • MDR (memory data register)
  • accumulator
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20
Q

In the CPU register what is the
program counter?
(definition)

A

holds the memory address of the next instruction to be executed.

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21
Q

In the CPU register what is the MAR?

what it stands for and definition

A

Memory address register

holds the memory address of the next instruction to be fetched

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22
Q

In the CPU register what is the MDR?

what it stands for and definition

A

memory data register

temporarily stores data fetched from main memory

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23
Q

In the CPU register what is the accumulator?

definition

A

temporarily stores the result of calculations completed by the ALU until they can be saved to main memory.

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24
Q

In the CPU what is a bus?

definition

A

A bus is a high speed internal connection.

Buses are used to send memory addresses, control signals and data between the processor and other components.

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25
Q

What is cache memory?

definition

A

In the CPU.

Cache memory is a small amount of very fast memory built into a CPU to store frequently used instructions. This can save time by preventing the CPU from having to fetch a common instruction from slower main memory (RAM) every time it needs it.

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26
Q

How does the CPU follow simple instructions?

A

by following the Fetch, Decode, Execute cycle.

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27
Q

what is fetch?

what happens / is the process?

A

Fetch, decode, execute cycle.

  • memory address of the next instruction is copied from program counter to MAR.
  • Instruction held in memory at this address is transferred to MDR.
  • Program counter is incremented (increased by one) so its pointing to next instruction ready for next cycle.
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28
Q

what is decode?

what happens / is the process?

A

Fetch, decode, execute cycle.

control unit splits instruction stored in MDR into 2 parts called opcode ( instruction itself) and operand (data or memory address to use).

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29
Q

what is execute?

what happens / is the process?

A

Fetch, decode, execute cycle.

Instruction is performed (could involve loading data from memory into register, calculating something with ALU and accumulator, or saving data from a register back into memory).

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30
Q

what is main memory also sometimes known as?

A
system memory
OR
primary storage
OR
random access memory (RAM)
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31
Q

what does RAM stand for?

A

Random Access Memory

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32
Q

what are both RAM and cache memory?

something that happens with both of them, not definitions

A

Volitile

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33
Q

what does volatile mean?

A

loose all stored data if power is turned off or if computer is shut down.

34
Q

What does ROM stand for?

A

Read only memory

35
Q

what happens when you boot a computer up with ROM?

(why is ROM needed?

A

When computer first switched on, RAM is empty (volatile) so CPU no instructions

ROM solves this problem.
it is a small microchip fitted to motherboard with just a few instructions to follow when computer first switched on

36
Q

What is ROM?

  • non volatile
  • stands for and meaning
A
  • non volatile, instructions always be available even if computer been off
  • read only memory, instructions cannot (easily) be changed or updated
37
Q

what are first instructions in ROM called?

A

start up / boot up sequence

SOMETIMES
known as bootstrap loader

38
Q

what does ROM start up sequence contain?

A
  • simple hardware tests
  • controls for basic input/output devices
  • instructions to load operating system from secondary storage device to main memory
39
Q

what is virtual memory known as?

A

fake RAM

40
Q

what is virtual memory used for?

A
  • RAM is limited in size so can be full, in some computers it will stop it from working
  • other computers can move data that hasn’t been used recently from RAM to a location on secondary storage (usually HDD) called Virtual memory so can carry on working
  • CPU can’t directly access data thats been moved to virtual memory, so data must first moved back to RAM before being used, so virtual memory makes computers slower when in use
41
Q

System performance.

CPU clock speed - what is it?

A
  • synchronises all parts of CPU by sending electronic pulses at constant rate. Number of clock ticks per second called clock speed and is measured in hertz.
42
Q

what is number of clock ticks in CPU clock called and measured in?

A

clock speed

Hertz

43
Q

CPU clock speed

how many instructions can a CPU with a clock speed of 2 Gigahertz process every second?

(fetch decode execute cycle)

A

2 billion

44
Q

what is affected / added when there is a higher number of CPU cores?

A

adding another core to CPU allows it to process MORE THAN ONE INSTRUCTION AT THE SAME TIME.

45
Q

What is CPU cache memory and what is it used for - what does this allow?

A

small amount of high speed memory built directly within the processor

used to temporarily hold data and instructions that the CPU is likely to resuse

allows for faster processing as CPU does not have to wait for data and instructions to be fetched from main memory

46
Q

what does the amount of RAM affect?

A

a limited amount of RAM means computer also be limited in NUMBER OF APPLICATIONS that it can run at one time

47
Q

what does GPU stand for and what is needed in order to run it?

A

graphics processing unit

requires a lot of processing due to complex math involved

to help CPU carry out some of the processing a specialist GRAPHICS PROCESSING UNIT (GPU) microchip can be added to a computer system

48
Q

GPU stands for…

A

Graphics Processing Unit

49
Q

what does SSD stand for and what does it do?

A

Solid state secondary storage

transfers data much faster
than older storage systems ie magnetic hard disk drives

50
Q

why do computers need secondary storage?

A

non volatile storage of data and instructions.
for long term storage of data, it must be saved by transferring it from volatile RAM into some form of non volatile secondary storage

51
Q

what are the categories of secondary storage?

A

solid state

optical

magnetic

52
Q

what is solid state? (examples)

A

category of secondary storage

solid state storage devices, such as USB sticks or solid state drives

53
Q

examples of optical

A

category of secondary storage

CD
DVD
Blu-Ray discs

54
Q

examples of magnetic

A

category of secondary storage

floppy discs
hard disc drives

55
Q

characteristics of solid state storage

A
  • made of silicon microchips (flash memory)
  • can be written to and overwritten like RAM
  • non volatile
  • no moving parts
  • small fast and durable
56
Q

advantage of solid state storage

A
  • small and lightweight (portable)
  • very fast data transfer speeds
  • durable and reliable (no moving parts)
  • low power consumption
57
Q

disadvantages of solid state storage

A
  • expensive
  • limited storage capacity
  • limited number of write cycles
58
Q

common uses of solid state storage

A
  • USB memory sticks
  • memory cards (digital cameras, games etc.)
  • internal storage for smartphones and tablets
  • SSDs are increasingly being installed in laptop and desktop computers
59
Q

characteristics of optical secondary storage

A
  • use a laser to scan surface of spinning disc made from metal and plastic.
    THERE ARE TWO TYPES:
  • read only have data pre printed on them
  • rewritable discs are blank
60
Q

advantages of optical storage

A
  • cheap to produce

- small and lightweight (portable)

61
Q

disadvantages of optical storage

A
  • easily scratched (not very durable)
  • very sensitive to movement
  • limited storage capacity
62
Q

common uses of optical storage

A
  • digital music (CD)
  • digital video (DVD and Blu-Ray)
  • video games (eg. PlayStation)
63
Q

Characteristics of magnetic storage

A
  • relatively old technology
  • includes tapes and floppy discs
  • tape or disk is coated with material that can be magnetised and tape drive or disk drive uses electromagnet to read and write data
64
Q

advantages of magnetic storage

A
  • high storage capacity
  • relatively low cost
  • reliable (if kept still)
65
Q

disadvantages of magnetic storage

A
  • bulky (not very portable)
  • slow data transfer speeds
  • very sensitive to movement (contains many moving parts)
  • high power consumption
66
Q

common uses of magnetic storage

A
  • server storage (hard disk drives)

- server backup (magnetic tapes)

67
Q

What is an operating system?

A

OS for short

system software that provides an important link between the computer hardware and the person using it.

68
Q

What are the 5 important functions of an operating system?

A
  • User interface
  • memory management and multi tasking
  • peripheral management and drivers
  • user management
  • file management
69
Q

describe user interface / characteristics

A

operating system

OS provides User Interface to allow user to interact with computer.

  • command line interface uses typed commands only
  • graphical user interface (GUI)
70
Q

Describe role of memory management and multi tasking

A

Operating System

runs application software.

71
Q

describe role of peripheral management and drivers

A

operating system

controls / communicates with peripheral devices

72
Q

Describe role of user managment

A

operating system

who can use the computer and what they can do with it + keeping computer secure ie. password etc

73
Q

describe role of file managment

A

operating system

computers store data in secondary storage files. FM is responsible for organising these files, allowing them to be renamed, moved and deleted. also be arranged into hierarchical structure using folders

74
Q

what is utility software?

A

a system software (often included with an operating system) designed to MAINTAIN OR CONFIGURE A COMPUTER.

75
Q

what are some examples of utility software?

A
  • virus scanners
  • system cleanup
  • backup software
  • battery monitor
  • data compression
  • encryption software
  • disk defragmentation
76
Q

what are virus scanners?

A

utility software

inspects files on computer looking for viruses. This software will download an up-to-date list of known viruses to look for

77
Q

what is system clean up?

A

utility software

will attempt to delete files on a computer that are no longer needed to free up space.

78
Q

what is backup software?

A

utility software

regularly copies files from a computer to some external or online storage, to protect against data loss

79
Q

what is battery monitor?

A

utility software

used to manage the battery in a mobile computer, usually switching to low power mode when battery is nearly empty

80
Q

what is data compression?

A

Utility software
used to compress or decompress files
files downloaded from internet are often compressed to speed up data transmission and so compression software needed to restore them to original size before use

81
Q

what is encryption software?

A

utility software

will scramble files so that even if they are stolen from a storage device they cannot be used

82
Q

what is disk defragmentation?

A

utility software

software will organise files (and the fragments of files) on a magnetic hard disk drive so that data can be accessed more quickly.