Topic 4. Organisation and structure of data

Calculations

- Make sure you know every conversion with binary, hexadecimal and denary

- Make sure you know binary addition and subtraction

When does an overflow occur?

In binary addition, when the answer is too large to fit into the register (it is 9 bits in length)

What are raster graphics?

They are dot matrix data structures representing a grid of pixels and cannot scale up without loss of apparent quality

Do raster graphics take up memory?

Yes, they tend to be large

in terms of the memory required to store them

What is a bitmap image?

A bitmap image is a type of raster image and is composed of many tiny parts, called pixels, which are often many different colours.

It is possible to edit each individual pixel

What are vector graphics?

Vector graphics use geometrically primitive

objects (geometric primitives) such as points, lines, curves, and shapes or polygons which are based on mathematical expressions to represent images

Can vector graphics be scaled up without loss of quality?

Vector graphics can be scaled up without loss of apparent quality

Do vector graphics take up memory?

Yes but they are smaller than

bitmap graphics in terms of the memory required to store them

How is sound stored as a digital representation?

Through sampling

What are the effects of sample rate and sample frequency?

The sample quality can be affected by the sample rate and sample frequency.

The higher the sample rate and frequency, the larger the resultant sample (file size) and the higher the quality

Name some examples of metadata in files

The file or artist, recording date, song title

How are characters represented in the internal parts of a computer?

As binary numbers

What is a standardised character set?

They allow for data interchange between different programs

Name 2 examples of standardised character sets

ASCII (American Standard Code for Information Interchange) and Unicode

Difference between ASCII and Unicode

Unicode can represent more characters than ASCII, but is more memory-hungry

What is an integer?

A whole number, 7, 0, 15, -5

What is Boolean?

True/False

What is a Real?

Integers that include decimals, 7.2, 8.9, -6.8, 12.0

What is a character?

A single letter, number or symbol (anything but only one of it), e.g. a, @, #, 8, Q

What is a String?

One or more character, e.g. Hello, abc, b, Y

What can you do to Data Structures?

- Describe

- Design

- Interpret

- Manipulate

Describe data structures

Describe relates to being able to describe and identify a data structure

For instance drawing a representation of a one-

dimensional array or a two-dimensional array

Design data structures

Design relates to being able to design an array or record that would be suitable for a

particular purpose (e.g. to design an array suitable for storing sales data over a time period

(Can also apply to files and records)

Interpret data structures

Interpret relates to being able to utilise a data structure to select data or to convert a graphical representation of an array to a programmed form or vice versa

Manipulate data structures

Manipulate relates to adding, deleting and editing data within an array or record

What are the types of validation?

"Robots Try Flying Planes Like Champions"

Range check, type check, format check, presence check, lookup table, check digit

What are the types of verification?

Double keying, proofreading