Fundamentals of Data Representation Flashcards
What are the 3 number bases?
Denary (base 10)
Binary (base 2)
Hexadecimal (base 16)
Why is hexadecimal often used?
Large numbers can be represented using fewer digits, therefore it is easier to understand
What are the rules for binary addition?
0 + 0 = 0
1 + 0 = 1
0 + 1 = 1
1 + 1 = 0 c 1
1 + 1 + 1 = 1 c 1
What are the rules of binary shift?
Shift left - multiplication
Shift right - division
Why does hex not save memory?
It must be converted to binary before the computer can understand it
What would a hex table look like?
16^1 16^0
How many bits does ASCII use?
7 bits
How many bits does extended ASCII use?
8 bits
How many possible ASCII characters are there?
128 = 2^7
Maximum bring 127 (0 inclusive)
How many bits does Unicode use?
16 bits
= 2^16 possible combinations
What are the limitations of ASCII?
No foreign languages
No special characters/ symbols (emojis)
Why must all data be converted to binary for a computer to be able to process it?
Computers work in binary
What is a digital bitmapped image?
An image made of pixels, where each pixel represents a binary number
What is the colour depth of an image?
The amount of bits available for colours in an image
How does colour depth affect file size?
The bigger the colour depth, the more bits are needed to represent a pixel, therefore the greater the file size
What is resolution?
The number of pixels in a specific area of an image
Measure in dpi (dots per inch) or ppi (pixels per inch)
What is metadata?
Extra data about data, including the file size
and resolution, colour depth, height and width
What is the amplitude of a sound wave?
Its height
What is the sample rate of a sound wave?
The number of samples recorded per second
Hz
What is bit depth in relation to sound (sample resolution)?
The number of bits used to record each sample
As sample resolution increases, quality and file size both increase
How do you find the file size of a bitmap image?
Width * height * colour depth
How do you calculate the file size of a sound file?
Rate * resolution * seconds
What is the purpose of data compression?
Reduce file size
Increase the speed of file transfer
How do you calculate bit rate?
Sample rate * resolution
