Data Representation Flashcards
Order and power of storage (bits)
2^1 bits, 2^2 nibbles, 2^3 bytes, 2^10 KB, 2^20 MB, 2^30 GB, 2^40 TB, 2^50PB
Storage for 1 ASCII character
1 byte
Storage for 1 UNICODE character
2 bytes
Hexadecimal base, characters and uses
Base 16, 0-9 then A-F, MAC Addresses/Html colour coding and computer error messages, IPV6 messages
How is data stored on a computer
In binary using 1s and 0s, on or off
What is a bitmap image
Bitmap (raster) images are comprised of small picture elements called pixels. Bitmaps blur when enlarged
What is a vector image
Vector images use mathematical expressions to describe how the image is created and do not blur when enlarged
JPG or JPEG images
JPG or JPEG is a type of bitmap image that has been compressed using lossy compression. When the image is enlarged it appears blurry.
Calculating bitmap file size
pixels down x pixels across x bit depth
divide answer by 8 to give in bytes
divide by 1024 if more than to give in KB
and so on till PB
Sound stored on a computer
Humans hear sound as analogue data that varies over time though computers work with digital data. Computers sample the sound at difference time intervals to best recreate it.
Sound sample rate
The more samples per time interval the better the quality of sound
Sound file size calculation
frequency (sample rate/hertz) x bit depth x length x channels
channels:
stereo is 2
5.1 is 6
7.1 is 8
Lossy compression of sound file
In an MP3 file lossy compression works by removing frequencies humans can’t hear well and/or at all
MIDI files
MIDI files don’t contain music or sounds, they contain a list of commands that instruct a device on what sound to produce, how loud, what frequency and for how long.
Video file storage
MP4 files allow for multimedia, sound and picture
