Memory & Storage

Question 1

Describe the differences between Primary and Secondary storage

Answer 1

Primary is quick, easily accessed by the CPU and is referred to as main memory (includes RAM and ROM). Secondary is slower however has a larger capacity and long-term

Question 2

Describe the difference between volatile and non-volatile storage

Answer 2

Volatile storage is temporary, which means data is lost when the power is turned off. Non-volatile storage saves data

Question 3

Why do computers need primary storage

Answer 3

Program instructions and data must be copied from the hard drive into RAM by the CPU because primary storage access speeds are much faster than secondary storage devices

Question 4

What is RAM and what information is stored in it

Answer 4

Random Access Memory is volatile storage which stores all the programs which are currently running. RAM is made up of a large number of storage locations, each can be identified with a unique address

Question 5

What is ROM and what information is stored in it

Answer 5

Read-Only Memory is non-volatile storage that cannot be changed. It stores BIOS for when the computer is switched on which will then load the operating system.

Question 6

What is Virtual Memory

Answer 6

Computers use the HDD instead of RAM if RAM becomes too full. New data will be stored in RAM and unused data will be stored in Virtual Memory

Question 7

Describe secondary storage and the characteristics

Answer 7

Non-volatile storage which can be accessed repeatedly. Capacity, cost, durability, portability, reliability and access speed

Question 7

Describe secondary storage and the characteristics

Answer 7

Non-volatile storage which can be accessed repeatedly. Capacity, cost, durability, portability, reliability and access speed

Question 8

Name the types of Magnetic storage and the characteristics

Answer 8

Magnetic HDD, floppy disk and magnetic tape which involves a disk platter and magnetic field to read/write data. Large capacity and cheaper than solid state, not durable or portable. Slow access but faster than optical

Question 9

Name the types of Optical storage and the characteristics

Answer 9

CD, DVD and Blu-ray which involves a laser projecting beams of light onto a spinning disk. Portable, cheapest, low capacity, not durable and slow access speed

Question 10

Name the types of Solid State storage and the characteristics

Answer 10

No moving parts SSD, USB and SD. High capacity but expensive. Durable and small and portable, fast access too

Question 11

Why do computers use binary

Answer 11

Computer systems consist of millions of tiny transistors which are switches with only two values: 1,0. Therefore all data must be represented and processed this way.

Question 12

List the units of data from smallest to largest

Answer 12

Bit = 1
Nibble = 2
Byte = 4
Kilobyte = 1000 bytes
Megabyte = 1000KB
Gigabyte = 1000MB
Terabyte = 1000GB
Petabyte = 1000TB

Question 13

Why is Hexadecimal numbers are used as an alternative to binary

Answer 13

It’s used as a shorthand for binary because it uses fewer character to write the same value. This makes hexadecimal less prone to errors when reading and writing it, compared to binary

Question 14

Explain what an overflow error is

Answer 14

When a binary value is too large to be stored in the bits available

Question 15

What effect does shifting to the left/right have on the binary value

Answer 15

Left: multiply
Right: divide

Question 16

What is a character set and why are they needed

Answer 16

A table that matches together a character and a binary value. Each character in a character set has a unique binary number that matches with it. They are necessary as they allow computers to exchange data and humans can input characters

Question 17

Describe three differences between ASCII and Unicode

Answer 17

ASCII: does not take up space, uses 1 byte and is enough for the english language
Unicode: allows 2 bytes, different languages however takes more space.

Question 18

What does ‘ASCII’ stand for

Answer 18

American Standard Code for Information Interchange

Question 19

Describe 3 differences between bitmap and vectors

Answer 19

Bitmap: made of pixels, each have an assigned binary value, depends of resolution
Vectors: drawn by precise mathematical instructions, smaller in file size, don’t lose quality

Question 20

How do you calculate file size

Answer 20

File size = resolution x colour depth

Question 21

Define resolution

Answer 21

The amount of pixels in an image

Question 22

Define colour depth

Answer 22

The number of bits used to represent each pixel’s colour

Question 23

How many colours represented in;
1 bit, 5 bits and a byte

Answer 23

1 bit: 2 colours
5 bits: 32 colours
1 byte: 256 colours

Question 24

What is metadata and give 3 examples for a graphics file

Answer 24

The additional data about a file, this ensures the dimensions of image can be displayed correctly. Colour depth, File type, Resolution

Question 25

How is an analogue sound wave converted into a binary sample

Answer 25

They must be digitally recorded and stored in binary. The amplitude is measured and recorded in binary as specific intervals

Question 26

Define sample rate

Answer 26

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

Question 27

How is an audio file affected when sample rate is increased

Answer 27

The higher the sample rate, the better the audio quality is

Question 28

What are the benefits of compressing a file

Answer 28

Takes up less storage, can be transferred quicker, can be read from or written quicker

Question 29

What are the differences between lossy and lossless compression

Answer 29

Lossy: Removes data which can’t be seen or heard by humans, removes data permanently and is often used with videos and audios
Lossless: Doesn’t permanently remove, usually larger and is done for executable files and word documents