Storage And Data Organisation Flashcards
Storage size order
Bit,nybble,byte,kilobyte,megabyte,gigabyte,terabyte,petabyte,exabyte,zettabyte,yottabyte
How many bits in a nybble?
4
How many megabytes in a gigabyte?
1024.
Divide by 1000
How many bits in a byte?
8
What is lossy compression?
With lossy compression, some data is removed and discarded, thereby reducing the overall amount of data and the size of the file.
An image can be compressed by reducing its colour depth.This reduces the range of colours that the image contains. In practice, this results in an averaging of shades of colours.
For example, a very light shade of green could be averaged with a not so light shade - the very light shade might be discarded and the pixels affected by it re-coloured with the darker shade.
What are some lossy standards?
JPEG
MPEG- file format compresses audio and video, making it more suitable for streaming media
MP3-lossy format for audio including music
What is lossless compression?
With lossless compression, files are reduced in size without the loss of data. However, lossless compression does not usually achieve the same file size reduction as lossy compression.
What is a one dimensional array?
Consists of a fixed number of elements of the same data type, stored in contiguous memory locations.
Computers tend to count from 0, so in the example above ‘Ivan Weber’ is 0, ‘Sue Thompkins’ is 1, and so on. This would be referenced in a program or pseudocode using the name of the array, in this case ‘Employees’, with the index in square brackets.
What is a 2 dimensional array?
a collection of data elements arranged in a grid-like structure with rows and columns
Key fact on arrays
A one-dimensional array can store only a single item of data about each record in the array. A two-dimensional array can store multiple items for each record.
