1.2 - Memory & Storage Flashcards
1
Q
What is RAM?
A
High speed, volatile memory
2
Q
What is the Operating system?
A
The software that manages the hardware and software resources in a computer system
3
Q
What does OS stand for?
A
Operating system
4
Q
Give an example of some programs that is stored in the RAM:
A
- Programs that is currently in use
- Open documents
- OS
5
Q
What does RAM stand for?
A
Random access memory
6
Q
What is ROM?
A
- Non-volatile, memory
- Stores instructions & data that are needed for the computer to run
7
Q
Give an example of a program that is stored in the ROM:
A
BIOS
8
Q
What is the purpose of the BIOS?
A
- Checks if hardware is functioning correctly
- Then, runs bootstrap program that loads the computer’s OS from the hard drive into the RAM
9
Q
What does ROM stand for?
A
Read only memory
10
Q
Where is the ROM located in the computer?
A
Built into the motherboard
11
Q
What is Volatile memory?
A
- Temporary memory
- Requires power to retain data
12
Q
What is Non-volatile memory?
A
- Permanent memory
—> Keeps its contents even when it has no data - Primary memory
13
Q
What is Primary storage?
A
Holds data, programs and instructions that are currently in use
14
Q
What does primary storage include?
A
- RAM
- ROM
- Cache
- Flash memory
15
Q
What is Primary storage also known as?
A
Main memory
16
Q
What is Virtual memory?
A
A section of a computer storage drive (HDD) which is temporarily used as RAM
17
Q
When is Virtual memory needed?
A
When you need to run applications on the computer than its physical memory (RAM) can support
—> It lets more memory to be used than there is in the system.
18
Q
What is Swapping?
A
The process of moving data between RAM and secondary storage when using virtual memory
19
Q
What are the disadvantages of using Virtual memory?
A
- Makes a computer slow to respond when switching applications
- Excessive use can cause disk thrashing
—> which decreases performance
20
Q
Why is Virtual memory slower to respond when switching applications?
A
In the VM, the data would still need to be moved to RAM before it could be accessed
—> This is what slows down the access speed
21
Q
How can the processing performance be improved of a computer that frequently uses virtual memory?
A
INCREASING the size of the RAM
—> reduces the need for virtual memory
22
Q
What is secondary storage?
A
Non-volatile memory external to the CPU and used for long-term storage of programs and data
23
Q
Name some common types of secondary storage:
A
- Optical
- Magnetic
- Solid State
24
Q
Name some examples of Optical storage devices:
A
- CD
- DVD
- Blu-ray discs
25
Name some examples of *Magnetic* storage devices:
* Hard disk drives
* Magnetic tape
26
Name some examples of *Solid state* storage devices:
* Solid state drives
* USB memory sticks
27
What does **HDD** stand for
Hard disk drive
28
Describe the structure of *HDD*:
Made up of a stack of magnetised metal disks
---> Spins 1000 times / sec
29
How is data stored in a *HDD*?
Magnetically
---> In small areas on the disks circular tracks
30
What is **Flash memory**?
Non-volatile memory that can be read from and written to
---> It is suitable for secondary storage
31
What are the *advantages* of **HDDs**?
* Cheap
* High capacity
* Fast read/write speed
32
What are the *disadvantages* of **HDDs**?
* Not portable
* Not durable - due to moving parts
33
What are the *advantages* of **SSD**?
* Durable
* Portable
* Fast
* Don't need defragmenting
34
What are the *disadvantages* of **SSD**?
* Expensive
35
What are the *disadvantages* of **Flash storage**?
* Small capacity
* Slower than SSDs
* Shorter read/write life
36
What are the *advantages* of **Optical discs**?
* Cheap
* Very easily portable
* Takes up little space physically
* Won't be damaged by water or shocks
37
What are the *disadvantages* of **Optical discs**?
* Less storage capacity compared to other types
* Easily scratched
* Requires a CD reader
* Slow write speeds
38
Where are *Magnetic tapes* often used?
* Personal computers
* Large organisations
* To sore HUGE amounts of data
39
What are the uses of *Optical storage*?
* Songs, videos and other multi-media storage
* Backup and archiving of data
40
What are the uses of *Optical storage*?
* Higher end computers
* Laptops
* Smartphones and tablets
41
Name some characteristics
* Capacity
* Speed
* Portability
* Durability
* Reliability
* Cost
42
What are **Bits**?
The smallest measurement of data
43
What are the units in computing, from smallest to largest?
* Bit
* Nibble
* Byte
* Kilobyte
* Megabyte
* Gigabyte
* Terabyte
* Petabyte
44
How do *computers* represent the **Flow of electricity**?
By using 1s and 0s
45
What *number* system do we use?
Decimal number system
46
How many digits does the **decimal number system** have?
10 digits (base 10)
47
What **base** is *binary*?
2
48
How do you convert from **denary** to **binary**?
49
How do you convert from **binary** to **denary**?
50
# Binary addition
0 + 0 = ?
0
51
# Binary addition
1 + 0 = ?
1
52
# Binary addition
1 + 1 = ?
0 carry 1
53
# Binary addition
1 + 1 + 1 = ?
1 carry 1
54
When does an **overflow** error occur?
When the result of a calculation requires more bits (place values) than are in the available range
55
How do you convert **hex** to **denary**?
56
How do you convert **denary** to **hex**?
Or divide the denary number by 16. Convert that first number into hex (if needed). Take the remainder and convert it into hex (if needed)
57
What *base* is **hexadecimal**?
16
58
Why might *programmers* use **hex** instead of **binary**?
Hex is easier to understand than binary.
Programmers often use hex to represent binary values as they are simpler to write and check than when using binary.
59
How are **binary numbers** multiplied and divided?
By shifting
60
How do you **multiply** a *binary* number?
Move the binary digits along to the left
61
How do you **multiply** a *binary* number by **2**?
All digits shift **one place** to the left
62
How do you **multiply** a *binary* number by **4**?
All digits shift **two places** to the left
63
How do you **multiply** a *binary* number by **8**?
All digits shift **three places** to the left
64
How do you **divide** a *binary* number?
Move the binary digits along to the right
65
How do you **divide** a *binary* number by **2**?
All digits shift **one place** to the right
66
How do you **divide** a *binary* number by **4**?
All digits shift **two places** to the right
67
How do you **divide** a *binary* number by **8**?
All digits shift **three places** to the right
68
What is a **character set**?
A table of data that links a character to a number. This allows the computer system to convert text into binary.
69
Give some *examples* of some **character sets**
* ASCII
* Unicode
* Extended ASCII
70
What is **ASCII**?
A 7-bit character set used for representing English keyboard characters.
71
How many **characters** does **ASCII** have?
128
72
What does **ASCII** stand for?
American Standard Code for Information Interchange
73
What is **Extended ASCII**?
Extended ASCII uses eight bits.
---> Allows for special characters such as those with accents in languages such as French and Spanish
74
How many **characters** does **Extended ASCII** have?
256
75
What is **Unicode**?
Unicode uses 16 bits, giving a range of over 65,000 characters. Represents languages such as Arabic or Chinese
76
How many **characters** does **Unicode** have?
Over 65,000
77
How do you *calculate* the **file size** of a **text file**?
number of bits per character x number of characters
78
What are the *types* of **images**?
* Bitmap
* Vector
79
What is a **pixel**?
Picture element - a single dot of colour in a digital bitmap image or on a computer screen
80
What are **bitmap images** made of?
Pixels arranged on a grid
81
How do **pixels** show colour?
Each pixel is assigned a binary value which represents the colour of that pixel
82
What does the *quality* of a **bitmap** image depend on?
Image resolution (total amount of pixels)
83
What is the *result* of scaling *up* a **bitmap image**?
It will result in visible loss of quality
84
Give some *examples* of **bitmap images**
Most images on computers (e.g. photos and screenshots)
85
What are **vector images**?
Drawn by the computer following precise mathematical instructions to create lines and objects
86
What is the *file size* of **vector images** compared to **bitmaps**?
Vector files are smaller compared to bitmaps
87
Why are **vector files** *smaller* than **bitmap images**?
As each pixel in a bitmap is stored as an individual binary value
88
What is the *result* of scaling *up* a **vector image**?
Scaled up without any loss of quality
89
What are **vector** images typically used for?
Logos and animations
90
What is **colour depth**?
The amount of bits available for colours in an image
91
What is **image size**?
The number of pixels that an image contains. It is expressed as height and width
| e.g. 1024 x 764
92
What is the **resolution** of an image?
The concentration of pixels within a certain area
93
How can you make a **greater range** of *shades & colours*?
By increasing the number of bits for each pixel
94
How do you work out **number of possible colours**?
Total num of colours = 2^n
n = numb of bits per pixel
95
How many *colours* does **one bit** represent?
2 colours
96
How many *colours* does **two bits** represent?
4 colours
97
How many *colours* does **three bits** represent?
8 colours
98
How many *colours* does **eight bits** represent?
256 colours
99
How many *colours* does the **RGB** model use?
3 bytes altogether:
1 byte of 256 colours each
100
How do you *calculate* the **file size** of an **image file**?
Image resolution x colour depth
101
What is **metadata**?
Additional data about a file
102
Give some *examples* of **metadata**
* Author details
* Colour depth
* Geolocation
* Date created
103
How do you convert **analogue sound** to **digital (binary)**?
Using an ADC. The amplitude of the analogue sound wave is measured and recorded in binary at specific intervals
104
What is a **sample**?
A digitally recorded fragment of sound, taken from an existing track or sound environment
105
What is **Sample rate**?
The number of times (per sec) the amplitude of the sound wave is measured
106
What is **sample rate** measured in?
Kilohertz (kHz)
107
Why will *increasing* the **sample rate** improve *audio quality*?
The digital data more closely resembles an analogue wave
108
What will **higher sample rates** result in?
Larger files
109
Why will **higher sample rates** result in **larger file sizes**?
As much more data is stored for each individual sample
110
How do you *improve* the quality of an **audio**?
* Increasing sample rate
* Increasing bit depth
111
What is **bit depth**?
Number of bits available to represent each sample
112
Why will *increasing* the **bit depth** improve *audio quality*?
The more bits available to be used for each sample.
---> Therefore quality is higher as the wave resembles more closely to an analogue wave
113
What will a **higher bit depth** result in?
Larger file size
114
Why will a **higher bit depth** result in **larger file sizes**?
As each sample stores additional bits
115
How do you *calculate* the **file size** of a **sound file**?
Sound file size = Sample rate (in Hz) x duration (s)
116
What is **compression**?
A method of reducing file sizes, particularly in digital media such as photos, audio and video
117
What are the **benefits** of **compression**?
* Files take up less storage space
* Files can be transferred quicker
* Files can be read from or written to quicker
118
What are the *methods* to **compress** a file?
* Lossy
* Lossless
119
How does **lossy compression** work?
Uses an algorithm that analyses and permanently removes data from the file which cannot be seen or heard by humans
---> This reduces file size
---> File can't return to its original form
120
What *type* of files would you often use **lossy compression** on?
* Images
* Audio
* Videos
121
What are some **advantages** of **lossy compression**?
* Greatly reduced file size
* Lossy files take up less bandwidth
* Commonly used
122
How does **lossy compression** positively impact **bandwidth**?
Can be downloaded more quickly
123
What are some **disadvantages** of **lossy compression**?
* Loses data that can't be brought back
* Can't be used on text or software files
* Worse quality than the original (but loss in quality is usually unnoticeable)
124
Give some examples of some *file types* that use **lossy compression**
* MP3
* JPEC
* AAC
125
How does **lossless compression** work?
Makes the file smaller by temporarily removing data to store the file. It returns to its original state when opened
126
What *type* of files would you often use **lossless compression** on?
* Word documents
* Programs
* Games
127
What are some **advantages** of **lossless compression**?
* No reduction in quality - data is temporarily removed
* Can be decompressed (turned back into the original)
* Can be used on text and software files
128
What are some **disadvantages** of **lossless compression**?
Only a SLIGHT reduction in file size - so it can still take up quite a bit of space
129
Give some examples of some *file types* that use **lossless compression**
* WAV
* PNG
* TIFF
