1.2 - memory & storage

Question 1

Primary storage

Answer 1

Also known as memory. Holds the data, programs and instructions currently in use. (includes RAM and ROM)

Question 2

RAM (random access memory)

Answer 2

Stores programs and data before they are
processed by the CPU. Read/write memory, meaning the contents can be changed. The contents are lost when the computer is turned off (Volatile)

Question 3

ROM (read only memory)

Answer 3

Data can be retrieved but not changed and the
contents are not lost when the computer is turned off. Used to store programs for an embedded system

Question 4

Volatile memory

Answer 4

Data stored in volatile memory is lost when the computer is turned off

Question 5

Non-volatile memory

Answer 5

Data stored in non-volatile memory is not lost when the computer is turned off

Question 6

Virtual memory

Answer 6

Space on the computers’ hard drive is used as main memory (extra RAM), if RAM is full. Virtual memory is slower than main memory

Question 7

Optical storage

Answer 7

A type of secondary storage which stores data on a spinning disk (made of plastic or metal). Data is read from and written to the disk using a laser.

Question 8

Magnetic storage

Answer 8

A type of secondary storage which uses magnetic fields to store data. A read/write head reads and writes data from the media.

Question 9

Solid state storage

Answer 9

A type of secondary storage which uses flash memory to store data. They have no moving parts and are much faster than optical or magnetic storage.

Question 10

HDD (hard disk drive)

Answer 10

A magnetic storage drive which can store large amounts of data and is often the main method of secondary storage in personal computers. The drive contains a number of internal disks and a read/write head used to read and write data.

Question 11

DVD (Digital Versatile Disk)

Answer 11

A high capacity optical storage disk commonly used for video storage. A range of capacities are available up to 17GB

Question 12

CD (Compact Disk)

Answer 12

An optical storage disk is regularly used to store music. Capacity is typically around 800mb

Question 13

SSD (Solid State Drive)

Answer 13

A solid state storage drive which carries out the function of a HDD. They are much faster than HDDs and less easy to damage as they have no moving parts. They are also more expensive and usually lower capacity.

Question 14

Capacity

Answer 14

the amount of storage available

Question 15

Cost

Answer 15

the price per gigabyte

Question 16

speed

Answer 16

how fast the read/write process is

Question 17

durability

Answer 17

how likely the storage is to break if it is dropped or worn over time

Question 18

reliability

Answer 18

how well the storage will function over time

Question 19

Portability

Answer 19

how easy it is to transport the storage device

Question 20

What are the advantages and disadvantages of magnetic storage?

Answer 20

Advantages:
- capacity - high storage (100 terabytes)
- cost - low per gigabyte (0.018)
- speed - moderate
Disadvantages:
- durability - moving parts easily damaged
- portability - heavy and bulky so less convenient
- reliability - often have mechanical failure

Question 21

What are the advantages and disadvantages of solid state storage?

Answer 21

Advantages:
- capacity - medium/high storage (128GB - 4TB)
- speed - very fast
- durability - no moving parts to damage
- portability - small and lightweight
Disadvantages:
- cost - high per gigabyte (0.15 to 0.50)
- reliability - limited read/write cycles

Question 22

What are the advantages and disadvantages of optical storage?

Answer 22

Advantages:
- cost - low per gigabyte (0.001)
- durability - no moving parts
- portability - small and no moving parts
Disadvantages:
- capacity - very low (700 MB - 25 GB)
- speed - very slow read/write access
- reliability - prone to scratches

Question 23

what is the ascending order of storage units?

Answer 23

• bit - either binary 0 or 1
• nibble - 4 bits (half a byte)
• byte - 8 bits
• Kilobyte (KB) - 1000 bytes
• Megabyte (MB) - 1000 KB
• Gigabyte (GB) - 1000 MB
• Terabyte (TB) - 1000 GB
• Petabyte (PB) - 1000 TB

Question 24

Binary

Answer 24

A number system used by computers. It contains only two symbols, 0 and 1. It is also known as base 2.

Question 25

Denary

Answer 25

The number system most often used by people. It uses the digits 0 to 9 and is also known as base 10 or decimal.

Question 26

Overflow Error

Answer 26

This happens when not enough space has been allocated to store the results of a calculation. For example, if one byte has been allocated but the result is 9 bits long.

Question 27

Hexadecimal

Answer 27

Uses 16 symbols: 0 to 9 and A to F. Letters are used to represent values 10 to 15. Also known as base-16

Question 28

Binary Shift

Answer 28

A process used to preform math on binary numbers. It involves moving all the digits to the left or right.

Question 29

Most Significant Bit

Answer 29

The furthest left digit in a string of binary numbers, its position means it has the highest value.

Question 30

Least Significant Bit

Answer 30

The furthest right digit in a string of binary numbers, its position means it has the lowest value.

Question 31

Character

Answer 31

A single symbol, for example a letter, number or punctuation mark.

Question 32

Character Set

Answer 32

A system for representing characters in binary, each character is assigned a unique binary number.

Question 33

ASCII

Answer 33

American Standard Code for Information Interchange. A 7 bit character set used to represent characters.

Question 34

Unicode

Answer 34

A much larger character set created to overcome the limited number of characters available in ASCII. It includes many different language characters and other symbols like emojis.

Question 35

Pixel

Answer 35

Short for Picture Element. Pictures on a computer are divided into a grid, with each square in the grid being one pixel which can be a single colour.

Question 36

Metadata

Answer 36

Additional data about a file such as when it was created or who created it. Commonly used with photos to store things like the make of camera or location the photo was taken.

Question 37

Colour Depth

Answer 37

The amount of bits available for colours in an image. The higher the colour depth the more colours available and therefore the more detailed the image will appear.

Question 38

Resolution

Answer 38

The number of pixels an image is divided into. The higher the resolution, the more pixels in the image and the clearer it will be.

Question 39

Sample Rate

Answer 39

The number of samples taken in one second. This is measured in hertz (Hz) - 1Hz is one sample per second. The higher the sample rate, the more samples per second and therefore the higher the quality of the file.

Question 40

Bit Depth

Answer 40

The number of bits available for each sample. The higher the bit depth, the more bits available and therefore the better the quality.

Question 41

Analogue

Answer 41

A continuously varying signal, usually represented as a curved line. Examples include sound or temperature recordings.

Question 42

Compression

Answer 42

A way of reducing the size of a file. It is often used with photos, music and video files.

Question 43

Lossy Compression

Answer 43

A compression method which reduces the file size by removing certain data. The original file cannot be restored from the compressed version but the file size is reduced by more than with lossless compression.

Question 44

Lossless Compression

Answer 44

A compression method which reduces the file size without losing any data. The original file can be restored from the compressed version, but the file size is not reduced by as much.