# Component 1.4 - Organisation And Structure Of Data (Finished) Flashcards Preview

## Computer-Science GCSE Revision (Paper 1) > Component 1.4 - Organisation And Structure Of Data (Finished) > Flashcards

Flashcards in Component 1.4 - Organisation And Structure Of Data (Finished) Deck (87)
1
Q

What is the denary counting system also known as?

A

The denary counting system is also known as the Base 10 or decimal counting system

2
Q

How does the denary counting system represent data?

A

The digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 are used to represent numbers, e.g. 138 1 ‘hundred’ 3 ‘tens’ 8 ‘units’

3
Q

What is the binary counting system also known as?

A

Binary counting systems is also known as the Base 2 counting system

4
Q

Why must data be converted to binary format in order for it to be processed by a computer system?

A

Computer systems can only store and process binary digits, BITs, which are either a 1 or a 0

5
Q

A binary number is ___ bits

A

A string of

6
Q

What is the hexidecimal counting system also known as?

A

The hexadecimal counting system is also known as the Base 16 counting system.

7
Q

How are numbers represented in the hexadecimal system?

A

the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 are used to represent 1–9 and then the characters A, B, C,
D, E and F are used torepresent 10 –15.

8
Q

Why are hexadecimal numbers widely used rather than binary?

A
```Hexadecimal is widely used as
binary numbers can be quickly
numbers that are more convenient
for humans to use.```
9
Q

What are shifts and what do they involve?

A

Shifts are manipulations of bit patterns. A shift involves moving the bits in a specified direction, either left or right, by a specified number of places

10
Q

What can arithmetic shifts be used for?

A

Doing division and multiplication

11
Q

What does logical shift right do?

A

Logical shift right divides a number by 2 with every shift

12
Q

How does logical shift right work?

A

76543210
00110100
- What was in bit position 0 (the right most bit) falls off the end and is lost forever.
- What was in bit position 1 moves to bit position 0.
- What was in bit position 2 moves to bit position 1.
- etc…
- A 0 is moved into bit position 7.

13
Q

What is the sign bit?

A

One way to represent negative numbers is through sign and magnitude. In this method, the bit at the far left of the bit pattern - the sign bit - indicates whether the number is positive or negative. The rest of the bits in the pattern store the size of the number (called its magnitude).
For example, with an 8-bit pattern, the first bit would be used to indicate positive or negative.0 can indicate a positive number and a 1 can indicate a negative number. The other seven bits would be used to store the actual size of the number.
For example, 10001001 could represent -9:

14
Q

What does arithmetic shift left do?

A

Arithmetic shift left multiplies an integer (binary number) by two

15
Q

What happens when the sign bit is eventually changed in arithmetic shift left?

A

An overflow occurs

16
Q

How does arithmetic shift left work?

A

76543210
00111010

• What was in bit position 0 moves to bit position 1.
• What was in bit position 1 moves to bit position 2.
• etc…
• What was in bit position 7 (the left most bit) falls off the end and is lost forever.
• A 0 is moved into bit position 0.
17
Q

What does arithmetic shift right do?

A

Arithmetic shift right will divide a binary number by 2 with every shift and preserve the sign of the number

18
Q

How does arithmetic shift right work?

A

The normal shift takes place, but the sign bit stays the same as the data shifts. So if the sign bit was 0, it will be filled in with a 0, if it was 1 it will be filled in with a 1

19
Q

How long can arithmetic shift left last for?

A

Arithmetic shift left works until the sign bit is changed, then an overflow occurs

20
Q

What is the process that converts sound into a digital signal called?

A

Sampling

21
Q

What happens in sampling?

A

Hardware measures the level of sound many times per second and records it as binary digits

22
Q

What is the sampling frequency?

A

The sampling frequency is the number of times that sound level is sampled per second

23
Q

The higher the ___ the ___ the quality of sound

A

Sampling frequency, higher

24
Q

What is bit rate (sound)?

A

The number of bits used per second of audio

25
Q

What is bit depth (sound)?

A

Bit depth is the number of bits available for each clip of sound

26
Q

How are bitmap images stored?

A

Botmap images are stored as an array of pixels

27
Q

How will a black and white bitmap image be stored?

A

It will be stored as an array with a 1 representing black pixel and 0 a white pixel

28
Q

How is a colour bitmap image stored?

A

It is stored in an array where each pixel is represented by a number that represents how much red, green and blue is required in the colour of it

29
Q

What is colour depth (of an image)?

A

It is how many colours are available for each pixel and is measured in bits

30
Q

What values would a 1 bot colour depth, 2 bit colour depth allow for?

A

1 - 1 or 0

2 - 00 01 10 11

31
Q

How do you calculate the number of colours available for each pixel (colour depth)

A

2^colour depth

So 5 bit colour depth 2^5 allows for 32 colours

32
Q

How many bits colour depth is needed for RGB?

A

24 bits will be needed, each pixel stores 24 bits, the first 8 e.g. 11111111 give red value, next 8 green etc. Each can store a number from 0-255

33
Q

What is the general file format for vector images?

A

SVG - scalable vector graphics

34
Q

What are some common bitmap file types?

A

JPEG, GIF, PNG

35
Q

What is done when zooming in on bitmap images?

A

When zooming in on bitmap images the pixels are stretched and enlarged

36
Q

How is a vector image stored?

A

A vector image uses scalable shapes e.g. lines and curves, using coordinates and geometry to precisely define parts of the image

37
Q

Why are vectors more efficient than bitmaps at storing large areas of colour?

A

Vectors do not need to store every pixel as bitmaps do so they are more efficient at storing large areas of one colour

38
Q

How are vector images displayed?

A

When a monitor wants to display a vector image it is rasterised - converted into a grid of pixels to be displayed

39
Q

A

40
Q

What would metadata contain (4 examples)?

A
• dimensions
• colour depth
• file format
• time and date when image changed
• camera settings when image taken
• resolution
41
Q

A

Metadata allows a computer to display an image correctly

42
Q

How are characters stored on a computer system?

A

Characters are stored as a binary number on a computer system

43
Q

What is a character set?

A

A character set is a table that maps a character with a unique binary number

44
Q

Why is a character set needed?

A

A character set allows for data exchange between computer systems as it allows them to recognise which binary number corresponds to which character as computer systems can represent characters differently

45
Q

What does ASCII stand for and what is it?

A

ASCII stands for American Standard Code for Information Interchange and is a 7- it character set

46
Q

What is the problem with the ASCII character set?

A

The problem with the ASCII character set is that it can only represent 128 different characters, and computer systems may need to be able to store more characters than this

47
Q

What is unicode and why is it useful?

A

Unicode is a standard character set that has combined and replaced many others. It allows for many different characters to be represented, many more than ASCII

48
Q

What does a real store?

A

Numbers, including fractions or decimals

49
Q

What are the most common data types?

A

Integer, real, boolean, character, string

50
Q

What is a data structure?

A

A data structure is a specific way of organising data within memory so that it can be processed efficiently

51
Q

What is a static data structure used for?

A

A static data structure is used to store a known number of data items

52
Q

What can be changed and what is fixed in a static data structure?

A

The values of data in a static data structure can be changed but the memory size is fixed.

53
Q

Why is an array an example of a static data structure?

A

You can change the values of elements in an array, but the size of it is (memory size allocated) is fixed

54
Q

When is memory allocated to data structures?

A

Memory is allocated to data structures at compile time

55
Q

What is the advantage of static data structures?

A

Static data structures are easier to program as there is no need to check the size of the data structure or number of items stored

56
Q

What is different about dynamic data structures from static data structures?

A

Dynamic data structures are designed to allow the data structure to grow or shrink at runtime, it is possible to add or remove elements without having to consider memory space

57
Q

A

Dynamic data structures make the most efficient use of memory but are more difficult to program

58
Q

How does a list data structure store data?

A

A lost stores data items in the order they were originally added to memory

59
Q

Is a list data structure dynamic or static?

A

If the list is made up of a set of number data items it can be static as the size is known, but if it varies in the number of data items it would be a dynamic data structure

60
Q

What is an array?

A

An array is a data structure that can hold a fixed number of data items of the same data type.

61
Q

How are elements in an array identified?

A

The elements in an array are identified by a number indicating their position in the array known as the index

62
Q

What are the basic operations that can be carried out in a one-dimensional array?

A

Transversing, insertion, deletion, search

63
Q

What is transversing (arrays)?

A

Transversing an array means using a loop to use each element in a section of a program (e.g. looping through a list, printing out each item)

64
Q

What is insertion in an array?

A

Insertion is adding an element into an array at a given index

65
Q

What is the index (arrays)?

A

The index is a number that indicates the position of an element in an array

66
Q

What is deletion in an array?

A

Deletion is removing an element from an array

67
Q

What is search in an array?

A

Areays can be searched using the index or the value stored at the index

68
Q

How are elements in a two dimensional array indexed vs a 1 dimensional array?

A

In a two dimensional array elements are indexed by two numbers, one for the row and one for the column unlike in a one dimensional one only one index number

69
Q

What are records used for?

A

The record data structure is used to store related data of different data types

70
Q

A

A record is made up of information about a person or thing, called a field. This is split up into a field name and field type

71
Q

What is a key field?

A

A key field is an item of data that is unique and can be used to identify the individual record. Each record in a file should have a key field

72
Q

How is a stored file output to the screen?

A

A program will load a file from secondary storage, e.g. hard disk, into the computer’s memory. The data will be manipulated bu the CPU and output to the screen.

73
Q

What is a file format?

A

A file format is a structure and organisation that data stored in a file would have

74
Q

How would it be most efficient to store the fields in a record in a data file and why?

A

It would be most efficient to store the fields in the record next to each other so that the data can be put into the record data structure in memory to be processed by the CPU

75
Q

What makes up files?

A

Files are made up of records of the same structure

76
Q

What makes up records?

A

Records are made up of fields containing information about a person or item

77
Q

What is validation?

A

Validation is a process used to check if input data is reasonable or sensible

78
Q

What are presence checks validation algorithms used for?

A

They are used to prevent further progress if a field is left blank

79
Q

What are Format checks validation algorithms used for?

A

Format checks are used to ensure data matches a specific pattern, e.g. did/mm/yyyy

80
Q

What are Length checks validation algorithms used for?

A

Length checks are used to ensure that an input data string is a sensible length

81
Q

What are Type checks validation algorithms used for?

A

Type checks are used to ensure that input data are a particular data type

82
Q

What are Range checks validation algorithms used for?

A

Range checks are used to ensure that input data lies within a specified range

83
Q

What are Look up checks validation algorithms used for?

A

Look up checks are used to ensure input data matches an item in a list of valid entries

84
Q

What is verification?

A

Verification is a process for chewing if data is correct

85
Q

When could verification be carried out?

A

When a user enters data, or when data is copied from one part of the system to another

86
Q

How does double entry data verification work?

A

Double entry involves using a verification algorithm to compare two versions of data input and inform the user if they are identical

87
Q

How does screen based verification work?

A

Screen based verification requires the user to check a display of input data and confirm that it is correct