3) Fundamentals of Data Representation Flashcards
Learn changing between binary, denary, hex Learn binary addition, subtraction, multiplication
How big is a nibble?
A nibble is 4 bits
How big is a byte?
A byte is 8 bits
Rank the storage units
Bit (1) Nibble (4) Byte (8) Kilobyte (1000B) Megabyte (1000KB) Gigabyte (1000MB) Terbayte (1000GB)
What is the equation for the capacity of a device?
required capacity = number of files x size of a single file
What digits does hexadecimal use?
Hexadecimal uses 0-9 then A-F (16 different symbols)
Why is hexadecimal used?
Allows us to find errors easier
What are advantages of hex?
Easier and faster to write 2 digits than the full binary sequence
Easier for a human to process than binary
Where is hex used?
Machine code
Assembly
HTML colours
MAC addresses
What is the RGB scale?
The RGB scale is 0-255
What is a MAC address?
A MAC address uniquely identifies a networked device
How many bits is a MAC address?
48 bits shown as 6 groups of 2 hex digits
How are MAC addresses structured?
The first 6 hex digits identify the device manufacturer
The second 6 hex digits identify the device serial number
What is an overflow error?
An overflow error is when a binary number is carried past the last place column during binary addition
How do you multiply or divide in binary?
You perform a binary shift where every number is shifted a set number of places
What are problems with binary shifting?
Data shifting off the left can cause an overflow error
Data shifting off the right can cause a loss of accuracy
What is a character set?
A collection of all of the characters that a computer recognises, along with their binary codes
What are some examples of character sets
ASCII (American Standard Code for Information Interchange)
Unicode
What is the most common character set?
ASCII is the most common character set
How many bits is each ASCII character?
Each ASCII character is represented by 7-bit binary code, this means there is a maximum of 128 characters
What are limitations of ASCII?
Does not include non-english special characters
Why was Unicode released?
Unicode was relseased due to the need to standardise charactrer sets internationally
How many bits is each Unicode character?
Each Unicode character is represented by between 8 and 48 bit binary codes
How are Unicode and ASCII compatible?
Unicode and ASCII are compatible because the first 256 characters are identical
What are most digital images stored as?
Bitmaps
What is colour depth?
The amount of bits used to store the colour of each pixel
What are common colour depths?
1-bit
8-bit
16-bit
24-bit
What is resolution?
The number of pixels in an image
What are examples of metadata?
Resolution
Colour depth
Encoding format
Time/ date of photo
How is image file size calculated?
file size (b) = image width x image height x colour depth (b)
How is image file size calculated with bytes (B)?
file size (B) = file size (b) / 8
What are black pixels stored as?
0
What is converted to digital sound?
Analogue waves
What is sampling?
When a sound’s amplitude is recorded at regular intervals
What is sample rate?
The number of samples taken per minute
How is quality of audio increased?
Increasing sampling rate
Increasing sample size
How is bit rate calculated?
Bitrate = sample rate x sample size
What is lossy compression?
Removing unnecessary details with data permanently lost
What is lossless compression?
Reducing file size with algorithms without losing any data
What is run length encoding (RLE)?
A form of lossless compression
Replaces repeating 1s and 0s with more efficient representation
What is huffman coding used for?
Long pieces of text
Lossless compression
How do you create a huffman tree?
Left branch = 0
Right branch = 1
More frequent characters at the top
