Storage Units & Binary

Question 1

What is a bit

Answer 1

A single binary digit eg 1 or 0

Question 2

What is a byte

Answer 2

A group of 8 bits

Question 3

What’s a nibble

Answer 3

4 bits are a nibble

Question 4

How many bytes make a kilobyte and how much do you multiply by to get to MB & beyond

Answer 4

1000bytes

X 1000 from each jump

Question 5

When counting in binary what do the deniers equivalents at the top go up in

Answer 5

X2

Question 6

1 & 0 are like a row of…

Answer 6

Light switches 1=on

Question 7

In binary addition

Answer 7

You carry 1 when it adds up to 2 however carry it till it is 0+0 and then add the left over 1

Question 8

What is overflow & sort of example

Answer 8

A computer stores things in finite space however if you can not represent a number in that amount of space as it is tooo large then overflow occurs and a glitch occurs for example 8 bits represent 256 numbers however you can’t fit 267 into that space

Question 9

To multiply in binary

Answer 9

Each shift to the left represents multiplication by two

Question 10

To divide in binary

Answer 10

Each shift to the right is dividing by 2

Question 11

Why do we use hex

Answer 11

It’s easier for humans to understand as it shortens a long string of numbers .

Question 12

Hex is what type of base

Answer 12

16

Question 13

Hex is represented in how many bits

Answer 13

4bits (nibble)

Question 14

Why do we use letters in hex

Answer 14

The smallest value in 4 bits is 0000 & the largest is 1111. This means we need to represent 1-15 denery values into hex but we on,y have numerical digits 0-9 so we use letter A- F. To represent 10-15.
For numbers above 15 the binary are split into groups of 4 (nibbles) & then represented

Question 15

To convert decimal to hex either

Answer 15

Divide by 16 and convert the answer & left over into hex eg 182/16=11 remainder 6 which gives us B6
Or convert it binary & then convert

Question 16

ASCII stands for

Answer 16

American Standard Computer for Information Interchange

Question 17

Normal ASCII uses how many bits which results in how many characters?

Answer 17

7 bits per character =127 decimal +1 = 128 characters

Question 18

Extended ASCII uses how many bits resulting in how many characters

Answer 18

8bits. Per character =256 characters

Question 19

Why do we use extended ASCII

Answer 19

So that we can also encompass the extra letters found in European languages

Question 20

Why do we use Unicode

Answer 20

Unicode represents all characters in all languages of the world

Question 21

Unicode uses how many bits per character

Answer 21

8-32 bits however same codes up to 127

Question 22

What is a drawing that you can create on powerpoint

Answer 22

Vector graphic

Question 23

To store images on computers they are broken up into the smalles elements called

Answer 23

Pixels

Question 24

Size of an image is represented directly as

Answer 24

Height & width in terms of pixels

Question 25

What is a bitmap image

Answer 25

Each pixel is specifically assigned a position & colour hence does not change when enlargened

Question 26

Colour depth is

Answer 26

The number of bits per pixel for example if there are 4 colours you need to work out what 4 is in a base of 2 . 2 squared = 4 . The power is how many bits so for 4 colours 2 bits are requires per pixel.

Question 27

If the colour depth increased

Answer 27

More bits are used so file size increases

Question 28

Size file in image

Answer 28

Size in bits= resolution x colour depth (bits per pixel)

Question 29

Resolution of images

Answer 29

Image width x image height

Question 30

To change bits into byte & then into KB

Answer 30

/8 to get bytes then x 100 to get KB

Question 31

What is ADC

Answer 31

An Analogue to digital converter used for sound

Question 32

Steps for converting a sound wave

Answer 32

Analogue sound received by mic
Converted into electrical analogue signal
The amplitude of the signal is measured at regular intervals so is sampled
The values are quantified by rounding to a level
The quantified values are stored as binary digits

Question 33

What is a sample in sound

Answer 33

The measure of the amplitude at a point in time

Question 34

What does the accuracy of analogue sound wave into digital depend upon

Answer 34

The sample resolution - the number of bits per sample - the more bits the better
The sample rate - frequency with which you record the amplitude ie number of sample per second - the more the better

Question 35

File size of a sample of sound

Answer 35

Sample rate x sample resolution x number of second

Question 36

Compression

Answer 36

Is making a file smaller

Question 37

We use compression to

Answer 37

Reduce amount of storage needed
Allow large files to be sent as an email transmitted
Allow file to be transmitted in less time owing to smaller file size

Question 38

Lossy compression is

Answer 38

When information is removed so bits are reduced eg image colour depth is reduced

Question 39

Repercussions of lossy compression

Answer 39

Information is lost eg quality of image decreases as less colours are used

Question 40

Lossless compression is

Answer 40

Is when the file is squashed but no information is lost

Question 41

Types of lossy (files)

Answer 41

Jpg

MP3

Question 42

Types of lossless (file)

Answer 42

Gif

Question 43

Run length encoding

Answer 43

Stored using frequency/data pairs

Useful on icons with many pixels of the same colour

Question 44

Huffman tree steps

Answer 44

Draw a table of frequency of each character
Start at the bottom with the smallest frequency in circle and two branches with letters off it. Then work your way up
Once you reach the top branches on the left are assigned 0 branches on the right are assigned 1. Then work your way down noting 0 & 1 until you get you a character of your choice and that would be the Huffman value of that particular character.