1. data representation

Question 1

how and why computers use binary
to represent all forms of data

Answer 1

Any form of data needs to be converted to binary to be processed by a computer
Data is processed using logic gates and stored in registers

Question 2

difference between denary, binary and
hexadecimal number systems

Answer 2

Denary is a base 10 system
Binary is a base 2 system
Hexadecimal is a base 16 system

Question 3

positive denary -> positive binary
and vice versa

Answer 3

practice

Question 4

positive denary -> positive hexadecimal
and vice versa

Answer 4

practice

Question 5

positive hexadecimal -> positive binary
and vice versa

Answer 5

practice

Question 6

what is hexadecimal? what is its function

Answer 6

base 16 system used to represent binary numbers in a more human-friendly form,A simpler way to remember binary-equivalent values, more possible values with a smaller/ shorter representation, and finally its used normally for colours and error messages

Question 7

adding binary

Answer 7

practice

Question 8

subtracting binary

Answer 8

practice

Question 9

what is an overflow and why does it happen in binary addition

Answer 9

Overflow errors occur when a computer system attempts to occupy its registers with value that is one bit larger than its capacity

Question 10

perform left and right logical shifts

Answer 10

practice

Question 11

what happens to the denary value of a binary number when performing a left logical shift

Answer 11

multiplies depending on the amount of shift 1= x2

Question 12

what happens to the denary value of a binary number when performing a right logical shift

Answer 12

divides depending on the amount of shifts eg 1= /2

Question 13

Use two’s complement to represent positive and negative 8-bit binary integers

Answer 13

practice

Question 14

Convert a positive binary or denary integer to a two’s complement 8-bit integer and vice versa

Answer 14

practice

Question 15

Convert a negative binary or denary integer to a two’s complement 8-bit integer and vice versa

Answer 15

practice

Question 16

how does a computer know that a two’s complement number is negative

Answer 16

1 in leftmost value/ digit

Question 17

how do computers represent texts

Answer 17

using binary digit, unique to each character so that it can be processed by a computer

Question 18

what is ascii

Answer 18

standard code for info interchange, used worldwide to represent characters in a computer system.
uses 7 bits to encode characters, can represent 128 characters

Question 19

what is unicode

Answer 19

uses 16 bits, developed after ascii because some languages use their unique characters, and didnt fit the character set provided by ascii

Question 20

what are digital sounds used by computers made up of?

Answer 20

digital waves, a sequence of ‘discrete’ signal meaning a complex series of ‘on’ and ‘off’ instructions.

Question 21

whats the difference between analogue and digital waves

Answer 21

analogue are what humans use as sound and digital is what computers use
analogue waves are smooth and digital waves arent

Question 22

what is sampling

Answer 22

the process in which a computer converts analogue waves into digital waves, to do this it takes measurments of; sample resolution and sample rate

Question 23

what is sample resolution

Answer 23

The number of bits used per sample.

Question 24

what is sample rate

Answer 24

The number of samples of an analogue audio signal taken in a second

Question 25

what happens to file size when we increase resolution

Answer 25

increases

Question 26

what happens when we increase the frequency/ sample rate of a sample, in regards to the file

Answer 26

file increases

Question 27

how are images stored in a computer

Answer 27

using binary digits, and pixels
pixels are the smallest identifiable measurements in an image, each pixel is given a binary number that relates to a specific colour

Question 28

what is image resolution

Answer 28

the number of pixels within an image, and this is normally described using the width and height of the image

Question 29

what happens when you increase the number of pixels in an image

Answer 29

the higher the resolution/ clearer better image, and the larger the file size

Question 30

give the units for storing data and what “they are made of”eg how many bits in a byte

Answer 30

bit- binary digit 1 or 0 (b)
nibble- 4 bits
byte- 8bits (B)
kibibyte- 1024 bytes (KiB)
mebibyte- 1024 kibibytes (MiB)
gibibyte- 1024 mebibytes (GiB)
tebibyte- 1024 gibibyte’s (TiB)
pebibyte- 1024 tebibyte’s (PiB)
exibibyte- 1024 pebibyte’s (EiB)

Question 31

what is the formula for image file size

Answer 31

(image width × image height) × bit depth

Question 32

what is the formula for sound file size

Answer 32

= sample rate × sample resolution × length of track

Question 33

what is 1KHz

Answer 33

1000 samples per second

Question 34

what is compression

Answer 34

The act of reducing the logical size of a file to something much smaller than the original size, to save storage space and improve processing time. by applying an algorithm

Question 35

benefits of compressing a file

Answer 35

-less bandwidth required (less time loading it)
– less storage space required
– shorter transmission time (sending it to someone)

Question 36

what is lossy compression

Answer 36

permanently removes some data from the original source file, meaning lower quality files
uses an algorithm that looks to remove detail that is barely noticeable
usedin files such as mp3, jpgs
not used for text documents

Question 37

what is lossless compression

Answer 37

does not lose any data from original file, produces larger files that lossy but better quality,does not remove quality
uses an algorithm that looks for repeat data, this can be groups and categorised and a token be given for where each group will be used in the reconstruction
often used in file texts and images eg. docx gifs pngs