Memory And Storage

Question 1

Primary storage vs secondary storage

Answer 1

Primary storage:
Very quick because it’s is directly accessed by the CPU
Typically smaller in storage size
Sometimes called ‘main memory’
Includes RAM and ROM

Secondary storage:
Slower because it’s is not directly accessed by the CPU
Typically larger in storage size
Used for long term storage of data and files because it’s non-volatile
Includes magnetic,optical and solid state storage

Question 2

What is volatile and non volatile memory

Answer 2

Volatile storage is temporary.Data is lost whenever the power is turned off

e.g. RAM

Non-volatile storage saves the data even when not being powered.Data can be stored long-term and accessed when the computer is turned on

E.g. ROM

Question 3

Why do computers need primary storage?

Answer 3

primary storage is a low capacity internal storage that can be directly accessed by the CPU

Question 4

What is RAM

Answer 4

RAM is Volatile (temporary)storage that stores all programs that are currently running.also stores parts of the operating system to be accessed by the CPU

Question 5

what is ROM

Answer 5

ROM is non-volatile storage that cannot be changed

ROM stores boot program/BIOS for when the computer is switched on.

Question 6

What is virtual memory and how does it work

Answer 6

Programs must be stored in RAM to be processed by the CPU.even if there’s insufficient space in RAM the computer can use the HDD (hard disk drive) as an extension of RAM-This is called virtual memory

Question 7

What is binary?

Answer 7

Binary is a number system consisting of entirely 1s and 0s

Question 8

Why do computers use binary?

Answer 8

Computer systems consist of billions of tiny transistors which are switches that only have two values -on(1) or off(0).Therefore all data must be represented and processed this way.

Question 9

Units of data storage:

Answer 9

Bits
4 bits=nibble
8 bits=1 byte
1000 bytes=1 kilobyte
1000 kilobytes=megabytes
1000 megabytes=1 gigabytes
1000 gigabytes=1 terabyte
1000 terabyte=1 petabytes

Question 10

Josh has 500MB of free space on his USB stick.Each image is 650KB. How many images can he store?

Answer 10

500 MB x 1000= 500,000KB

500,000 KB / 650KB = 769 images

Question 11

What is denary?

Answer 11

Denary(also known as decimal) is a base 10 number system. This means that it has 10 possible values - 0,1,2,3,4,5,6,7,8 and 9

Question 12

What is hexadecimal?

Answer 12

Hexadecimal is a base 16 number system.This means that it has 16 possible values - 0,1,2,3,4,5,6,7,8,9A,B,C,D,E and F

10=A
11=B
12=C
13=D
14=E
15=F

Question 13

How to covert binary to hexadecimal:

Answer 13

1)Write out the binary number to convert
2)split the binary number into 2 groups
3)work out the hexadecimal value of each nibble

It can also either be 2 numbers
E.G. 38

Or 2 letters
E.G. EF

Question 14

How to convert denary to hexadecimal

Answer 14

easiest way is to covert to denary number into binary and go from there

Question 15

How to add binary digits:

Answer 15

0+0=0
1+0=1
1+1=(little 1)0
1+1+1=(little 1)1

Write the two binary numbers ontop of each other

01010100
01110110
—————
11001010

Question 16

What is an overflow error?

Answer 16

an overflow error occurs when a binary value is too large to be stored in the bits available

Question 17

What is binary shifts and what is the effects of shifting left and right

Answer 17

Used to multiply and divide binary number

the effect of shifting left is to multiply a binary number

the effect of shifting right is to divide a binary number

shifting by 1 has an effect of 2
Shifting by 2 has an effect of 4
Shifting by 3 has an effect of 8

Question 18

What is a character set

Answer 18

A character set is a table that matches together a character and a binary value

Question 19

What is ascii

Answer 19

Ascii is a common character set and uses 1 byte which only gives 256 possible characters but uses less memory to use

Enough for the English language

Question 20

What is Unicode

Answer 20

A more popular character set because it uses 2 bytes that allow for 65536 possible characters

This allows many different languages to be represented and thousands of symbols and emojis but it requires a lot more memory to store each character than ASCII

Question 21

What is the equation of file size of text files

Answer 21

Bits per character x number of characters

Question 22

A small text file uses ASCII character set (which uses 8 bits per character).There are 300 characters in the file.

Answer 22

300 x 8=2,400

Question 23

What are bitmap images made out of

Answer 23

Made of pixels single colour squares arranged on a grid

Question 24

What does the quality of a bitmap image depend on

Answer 24

The total amount of pixels this is known as image resolution

Question 25

How to calculate file size of a bitmap

Answer 25

File size= resolution x colour depth

Question 26

What is resolution of an image

Answer 26

The resolution of an image is the width in pixels multiplied by the height of pixels

Question 27

What is colour depth?

Answer 27

The number of bits that are used to represent each pixels colour 1 bit = 2 colours 2 bits = 4 colours 3 bits = 8 colours 4 bits = 16 colours ETC a colour depth of 1 byte allows for 256 different colours

Question 28

What is metadata and what does it include

Answer 28

Additional data about a file Includes: height and width in pixels Colour depth Resolution geolocation Data created last edited file type Author details

Question 29

What must analogue sound waves be recorded in and stored in

Answer 29

Must be digitally recorded and stored in binary

Question 30

How do you get a high quality sound

Answer 30

Many samples are taken to recreate the analogue wave as closely as possible.

Question 31

What is sample rate

Answer 31

The number of times per second the amplitude of the sound wave is measured.

Question 32

What is sound measured in and give an example

Answer 32

Kilohertz (KHZ) CD quality is 44.1kHZ(44,100 samples per second)

Question 33

Why does higher sample rate mean better audio quality and what is a drawback of this

Answer 33

The digital data more closely resembles an analogue wave However higher sample rates result in larger file sizes because more data is stored for each individual sample

Question 34

Why will a low sample rate result in low quality sound

Answer 34

The digital data does not closely resemble the original analog wave

Question 35

How to calculate sound file size?

Answer 35

Sound file size=sample rate x bit depth x duration

Question 36

A short audio has a bit depth of 4 and a sample rate of 10 samples per second.The clip is 15 seconds long. Calculate the file size

Answer 36

4 bits x 10= 40 bits per second, 40 x 15=600 bits Convert bits to bytes 600 bits / 8 =75 bytes

Question 37

What is compression

Answer 37

To compress a file means to make its smaller

Question 38

Benefits of compression:

Answer 38

Files take up less storage space Files can be transferred quicker Files can be read from or written to quicker result in faster load times and less strain on servers and networks Some email services have file size limitations and compression can help stay within these limits

Question 39

How does lossy compression work

Answer 39

Lossy compression uses an algorithm to analyse a file and remove data that cannot be heard of seen by humans Lossy compression will remove data that humans can see/hear Lossy compression removes the data permanently so the file never returns to its original form

Question 40

What is lossy compression commonly used with

Answer 40

Images,audio and video to reduce file size

Question 41

How does LOSSLESS compression work

Answer 41

Reduces the file size without permanently removing any data.Because of this the file returned to its original form when compressed so no quality is lost.

Question 42

What is lossless compression commonly used for

Answer 42

used with files that would not function properly if data were permanently removed, such as executable files (programs and games) or word documents