1.2 Memory and storage

Question 1

Why do we need primary storage?

Answer 1

The processor cannot get instructions straight from the hard drive because the access speed is slow. RAM acts as a temporary storage for programs and data while the program is being executed.

Question 2

3 features of RAM

Answer 2

Volatile - data is lost when the power is turned off, used to store data currently in use, can be written to / read from

Question 3

3 features of ROM

Answer 3

Non-volatile - data is not lost when power is turned off, store the BIOS/bootstrap loader - required at start-up, read-only

Question 4

Define virtual memory

Answer 4

A memory management capability that uses secondary storage as RAM and holds instructions that are in use.

Question 5

Why do we need secondary storage?

Answer 5

Computers need to be able store programs and data that is non-volatile for later use.

Question 6

3 common types of storage

Answer 6

Optical, magnetic, solid-state

Question 7

3 features of optical storage

Answer 7

Low capacity, slow access to data, portable (thin/lightweight)

Question 8

4 features of magnetic storage

Answer 8

High capacity, medium / quick access to data, moving parts which will eventually fail, perform better if defragmented

Question 9

6 features of solid-state storage

Answer 9

Medium storage capacity, very quick access to data, reliable (no moving parts), no noise, limited number of read/write cycles, expensive

Question 10

6 things to consider when choosing a storage device

Answer 10

Capacity, speed, portability, durability, reliability, cost

Question 11

Smallest unit of data

Answer 11

Bit

Question 12

How many bits in a nibble and byte?

Answer 12

4 and 8

Question 13

Hexadecimal number A in denary

Answer 13

10

Question 14

Denary number F in hexadecimal

Answer 14

15

Question 15

How to divide a binary number by 2?

Answer 15

Move all the digits to the right.

Question 16

Define character set, give 2 examples

Answer 16

The name given to a collection of characters matching to binary codes. Examples: ASCII, Unicode

Question 17

How many bits are used to represent how many characters in ASCII?

Answer 17

7-bits to represent 127 characters.

Question 18

How are images represented in binary?

Answer 18

Each pixel has a specific colour, represented by a binary number.

Question 19

Define metadata

Answer 19

Data that stored before and after the image to tell the computer how to decode the image.

Question 20

Define colour depth

Answer 20

The number of bits used to represent each pixel in a bitmap image.

Question 21

Define resolution

Answer 21

The number of pixels contained on a display monitor, measured in DPI (dots per inch).

Question 22

How is sound stored in digital form?

Answer 22

Using an analogue-to-digital converter. This will capture a sound wave at regular time intervals and convert it into binary form.

Question 23

Define sample rate and what is it measured in

Answer 23

The number of samples recorded in any given period of time (measured in hertz - Hz).

Question 24

Define bit depth

Answer 24

The number of bits used to record each sample (typical bit depths are 16 bit and 24 bit.

Question 25

Why do we need compression?

Answer 25

To reduce the size of a file stored on secondary storage. This takes up less storage space and power when transferring data.

Question 26

What is lossless compression?

Answer 26

Gets rid of unnecessary data to re-present data without losing any information - reversible process.

Question 27

What is lossy compression?

Answer 27

Gets rid of the least essential data - irreversible process.