Fundamentals of Data Representation Flashcards
Integer Numbers
Set of whole numbers, including positive and negative and zero
Z
Rational Numbers
Set of integer numbers but can contain fractional parts
Q
Irrational Number
Numbers which cannot be written as an exact fraction
No Symbol
Real Numbers
All possible real world quantities
R
Ordinal Numbers
Describe the numerical position of an object in relation to others
Kibibyte in Bytes
2^10
Mebibyte in Bytes
2^20
Gibibyte in Bytes
2^30
Tebibyte in Bytes
2^40
Kilobyte in Bytes
10^3
Megabyte in Bytes
10^6
Gigabyte in Bytes
10^9
Terabyte in Bytes
10^12
Unsigned Binary Numbers
Only represent positive numbers
Signed Binary Numbers
Allow for the representation of negative numbers
Absolute Error with Equation
Actual amount by which a value is inaccurate
Difference between the values
Relative Error with Equation
The measure of uncertainty between a given value compared to the actual value relative to the size of the given value
Relative Error = Absolute Error / Actual Value
Underflow Error
When numbers are too small to be represented with bits available
Overflow Error
When numbers are too large to be represented with bits available
ASCII
Character set which can represent alphanumeric characters or symbols as a set of 8 bits (128 different characters)
Unicode
Character set which includes more characters and symbols than ASCII as a set of 8 bits
Parity Bit
Single bit which is added to a transmission of data in order to check for errors. Even and odd parity (Counts number of 1s)
Majority Voting
Error checking technique where each bit of the data is transmitted multiple times where the most occurring value is taken, can check and correct the error
Checksums
Error checking technique where a piece of data is added to the block of data in order to enable error detection
Check Digit
Type of checksum where a single digit is added to the transmission
Bitmap Graphics
Images are broken down into many pixels which are each assigned a binary value
Resolution
The number of pixels in an image
Colour Depth
Number of bits assigned to each pixel which can determine colours available
Metadata
Data which is related to the image file itself, like width, height and colour depth
Vector Graphics
Way of representing images using geometric shapes and objects
Properties of Vector Graphics
Fill colour, fill style, line colour, dimensions…
Vector Graphics Vs Bitmapped Graphics
Vector Graphics can be scaled without losing quality. Vector Graphics are better for simple images like logos but are not useful for photographs. Vector Graphics often use less storage space.
Sampling Rate
Number of samples per second (Hz)
Sample Resolution
Number of bits given to each sample
Size of a Sound Sample (Equation)
Duration of sample (sec) x Sampling Rate (Hz) x Sampling Resolution
The Nyquist Theorem
The sampling rate of an audio file must be at least twice the frequency of the sound
Musical Instrument Digital Interface (MIDI) with examples
Used with electronic musical instruments which stores sound as a sequence of event messages (instructions)
Duration of note
Type of instrument
Volume of note
Advantages and Disadvantages of MIDI
Music can be manipulated easily without the loss of quality, note sounds can be altered and they are often smaller in size. But, they are not good at storing speech so can sound less realistic
Lossy Compression
Type of data compression where some data is lost, like reducing the sample resolution or image resolution
Lossless Compression
Type of data compression where no data is lost so can be reduced without decreasing the quality like run-length encoding and dictionary based methods
Run Length Encoding (RLE)
Reduces the size of file by removing repeated information by replacing it with one occurrence of value and by how much it is repeated
Encyption
The process of scrambling data so it cannot be understood if intercepted
Caesar Cipher (2 types)
Type of Cipher where data is encrypted by replacing each character by the same key
Shift Cipher
Substitution Cipher
Shift Cipher
Type of Caesar Cipher where all characters in the alphabet are shifted by the same amount (Key)
Substitution Cipher
Type of Caesar Cipher where all characters are randomly replaced
Disadvantages of Caesar Cipher
Can be cracked easily as frequency that characters occur could provide a clue. When one character is discovered in a shift cipher, all characters are found, but substitution are a little harder to crack
Vernam Cipher
Type of cipher where each key is only used once for each character in the plaintext. Uses the binary value of character and key and applies a XOR operation in order to get the ciphertext.
