Data representation

Question 1

How many digits is hexadecimal made up of?

Answer 1

16 –> 1-9 and A-F

Question 2

What is hexadecimal referred to?

Answer 2

Base-16 number system

Question 3

How many bits of binary data can one hexadecimal digit represent?

Answer 3

4 (a nibble)

Question 4

What are examples of hexadecimal being used?

Answer 4

-MAC addresses
-Colour values
-Short representation of binary numbers
-IP (version 6 only) addresses

Question 5

Why does data have to be converted to binary to be processed by a computer?

Answer 5

-computers are built using switches that can either be on or off, which fits the binary number system (1’s and 0’s)
-A quicker process time

Question 6

Define binary data

Answer 6

-represented by only 1 and 0.

Question 7

What is 1000 byte equal to

Answer 7

1 Kilobyte

Question 8

What is 1000 kilobyte equal to (Megabytes)

Answer 8

1 Megabyte

Question 9

What is 1000 Megabyte equal to
(Gigabytes)

Answer 9

1 Gigabyte

Question 10

What is 1 KiBi byte equal to
(bytes)

Answer 10

1024 Bytes

Question 11

Convert the following into denary:

a)10101110
b)00010001
c)10011111
d)00100111

Answer 11

a)174
b)17
c)159
d)39

Question 12

Convert the following into binary:

a)10
b)257
c)19
d)39

Answer 12

a)1010
b)100000001
c)10011
d)111001

Question 13

How to convert denary into hexadecimal

Answer 13

-Convert denary into binary
- Split the binary number into groups of four
-For each group of four, assign it the the hexadecimal value (e.g 1010–>A or 1000–>8)

Question 14

How to add binary number

Answer 14

0+0=0
1+0=1
1+1=0 and 1 carry forward
1+1+1=1 and 1 carry forward

Question 15

What is a overflow error

Answer 15

When a binary digit is needed to carry forward to the 9th bit but the answer only allow a 8 bit answer

Question 16

What is the maximum number for a 8 bit binary number

Answer 16

255

Question 17

What does binary shift do and what’s the difference between left shift and right shift

Answer 17

Left shift is multiplication
while
right shift is division

Question 18

What does shifting 2 place to the left means

Answer 18

Multiplying by 4

Question 19

What does shifting 3 place to the right means

Answer 19

Dividing by 8

Question 20

How to represent a negative number

Answer 20

By a 2’s complement

Question 21

How to perform a 2’s complement

Answer 21

Reversing a binary number ( 0–>1 and 1–>0)

And then add 1 to the last digit of the reversed binary

Question 22

What is ASCII

Answer 22

American Standard code for information interchange

Which will translate English language into binary/hexadecimal value

Question 23

What is Unicode

Answer 23

An interchange system which translate most language/emoji in the world into binary/hexadecimal

Question 24

What is the difference between ASCII and Unicode

Answer 24

ASCII is only used for the English Language while Unicode has many

ASCII have 7 bit per char but Unicode have 16 bit

ASCII have only 128 char that include everything in the English language and 1-9 and symbols

Unicode has over 65,000 char for different language and also math symbol and emoji

Unicode takes up more space in the file

Unicode is backwards compactable with ASCII (so first 128 char are the same in both Unicode and ASCII)

Question 25

What is a pixel

Answer 25

one small square of illumination that will create a image combined with different pixel of different colour in a bitmap (2D matrix)

Question 26

How is colour added to a pixel

Answer 26

by using RGB at different intensities

Question 27

What is colour depth

Answer 27

-number of bits used to represent the colour of a pixel e.g 1 bit pixel --> colour depth =2 3 bit pixel--> colour depth=8 2^ bit pixel

Question 28

What is meant by image resolution and how does it affect the quality

Answer 28

-level of detail in an image The higher the resolution the higher the quality

Question 29

What is image meta data

Answer 29

It is information about the image itself that is provided by the image itself. An example of this is the time the image is taken or creation day. Another example is how the image is organising.

Question 30

Example of meta data

Answer 30

Camera setting data created file size/type description Location of taken

Question 31

What type of wave are sound recorded in and what type of wave do computer read

Answer 31

-recorded in analogue wave -computers read as digital waves

Question 32

What is a ADC

Answer 32

Analogue digital convertor for sound wave e.g microphone

Question 33

How is a sound wave splited

Answer 33

Quantisation

Question 34

What is bit rate

Answer 34

-how many bits are sampled at a time

Question 35

Why do you need file compression

Answer 35

1. To save storage space on storage devices/ cloud storages 2. Media files occupying less space on the web service can make a website load faster 3. Data transmission becomes faster over a network 4. Makes it shareable

Question 36

What are the two type of compression

Answer 36

Lossy and Lossless

Question 37

Describe Lossy compression for image and sound file

Answer 37

Some data is removed completely to decrease file size -For an image, the **colour depth will decrease as the bit depth will** decrease..This means there will less shade of colour and the variety of colour will decrease -For audio, the **sample rate** taken in by the analogue-digital convertor decreases to decrease the **bit depth of the audio** Irreversible

Question 38

Describe Lossless compression

Answer 38

Used in file that contain important data which can't be removed Reconstruct the data in another less space needed form Won't decrease the quality though Though it will decrease the file less than lossy

Question 39

One example of Lossless compression and how does it compress

Answer 39

Run Length Encoding Compress repeating data into a smaller version e.g (AAAAABBBC into 5A3BC)

Question 40

File format for pictures

Answer 40

.JPEG

Question 41

File format for text

Answer 41

.txt

Question 42

File format for sound

Answer 42

.mp3

Question 43

File format for video

Answer 43

.mp4

Question 44

What is decomposition

Answer 44

Breaking down a bigger problem into smaller sets of problem

Question 45

What is the four stage to a software development life cycle

Answer 45

Analysis Design Coding Testing