Units, Numbers, Characters, Images and Sounds

4 bits

8 bits

1,000 bytes

1,000 kilobytes
1,000,000 bytes

1,000 megabytes
1,000,000,000 bytes

1,000 gigabytes
1,000,000,000,000 bytes

1,000 terabytes
1,000,000,000,000,000 bytes

It is easy to store two states with electrical components
Computers can only process data in binary format
To be compatible with existing systems

sound file size = sample rate x duration (s) x bit depth

image file size = colour depth x image height (px) x image width (px)

text file size = bits per character x number of characters

how much data can be stored on the device

a binary digit
the smallest unit a computer can store
either a 1 or 0

a base 2 number system
a numbering system in which there are only two possible values for each digit: 0 and 1

An error that occurs when the computer attempts to handle a number that is too large for it

0-255

00-FF

left-most value in a binary number
holds the highest place value

Holds lowest place value
right-most value in a binary number

Representing an image as a series of pixels, each one stored in binary

The file size increases

The file size increases

Additional data stored with an image such as width and height and colour depth

Number of bits used to store each sample

A defined list of characters recognised by the computer hardware and software

The result of a calculation cannot be stored in a register

Number of samples stored per second

The detail of an image determined by the colour depth and resolution

The finished quality of the digital sound file
Affected by sample rate and bit-depth

The number of pixels contained on an image expressed in terms of pixels on the horizontal and vertical axis

The number of bits used to store a single pixel
Determined by the number of colours in the image

A single dot of colour in a bitmap image or on a computer screen

American Standard Code for Information Interchange
a character set
each character is represented by a number
1 character is 8 bits (1 byte)

A character set
Stores characters from all the world languages including ancient languages
in 16-bit unicode, 1 character is 16 bits (2 bytes)
in 32-bit unicode, 1 character is 32 bits (4 bytes)

1 character is 4 bits (a nibble)

Easier to read for humans
Uses fewer digits to represent a number than binary and therefore is less likely to have input errors
Is easy to convert into binary as each binary nibble is a single digit in hexadecimal
Used to define colours in graphics software, to represent MAC addresses, to display addresses and for checksums

ASCII is used as a character set
Each character has a unique binary code
A standard like ASCII is used so that all manufacturers use the same code for each symbol

Quality of image improves
File size will increase
Number of colours that can be represented will increase

An analogue-to-digital converter will capture a sound wave at regular time intervals. This recording is known as a sample
The sound recorded at each sample point is converted to its nearest numeric equivalent
Sample rate is the number of samples recorded in any given period of time. The higher the sample rate, the closer the recorded signal is to the original. Sample rate is measured in hertz