Memory and Storage

RAM

Random Access Memory

What does it mean if memory is volatile

The memory loses its data once power is lost

What does it mean if memory is non-volatile

The memory retains its data even if power is lost

What is main memory needed for and give an example of main memory

• To store programs, data and instructions that the computer needs whilst it is still running

• RAM

For even faster access to data, frequently used data is stored in the _____

cache

Why do we use main memory

It has faster read/write speeds that secondary storage

Characteristics of RAM

• Volatile

• Can be written from and read to

• Used as computer’s working memory for instructions, programs and data

What does ROM stand for

Read Only Memory

What is ROM

Contains the BIOS

What is the BIOS (2 line answer)

• Basic Input Output System

• The instructions and data a computer needs to properly boot up

ROM characteristics

• non-volatile

• read only

• Contains the computer’s start up instructions

What is virtual memory

Secondary storage being used as an extension to the RAM

Why does a computer use virtual memory

There is no more storage left in the RAM

What is the disadvantage of virtual memory and why?

Virtual memory slows does the computer because it has slower read/write speeds than RAM

What does it mean if more RAM is available?

More data can be stored in the RAM and accessed faster.

What category of storage do HDDs fall under

magnetic storage

What does HDD stand for

Hard Disk Drive

How is data accessed from magnetic storage

A moving arm can access these areas and read/write data

What are advantages of HDDs

• Reliable

• Low cost per GB

• large capacity

Disadvantages of HDDs

• Slow read/write speed at 200MB/s

• Not robust, because moving parts can break easily

• Low portability, because they take lots of space

What does SSD stand for

Solid State Storage

What do most SSDs use

Flash memory

Advantages of SSDs

• Good amount of capacity

• High speed

• High portable, not much space needed

• Durable

• Reliable

• Lightweight so good for mobile devices

Disadvantages of SSDs

• High cost

• Limited read/write cycles so shorter lifespan

Binary shift to the left

multiply by 2

binary shift to the right

divide by 2

bit depth

the number of bits available to store an audio sampleb

bit rate

the number of bits processer per second

colour depth

the number of bits available for colours in an image

compression

a method of reducing file size

how many bits per character in ASCII

7

How many bits per character in Unicode

16

Lossless compression advantages

• No data is lost

• File can be restored to original size

Lossless compression disadvantages

Less reduction in filesize

Lossy compression advantages

• Large reduction in filesize

• Reduces internet traffic

Lossy compression disadvantages

data is permanently lost

What is lossless used for

text documents

ebooks

What is lossy compression used for

music streaming

online images and video

pixel

a single dot of colour

resolution

the fineness of detail that can be seen in an image

sample rate

how many samples are stored per secondfi

file size calculation

sampling frequency bit depth legnth

bit rate

the number of bits processer per second