Topic 1-Digital Data Flashcards
1
Q
Difference between information and data
A
- An information system processes data and produces information
- Data consists of raw facts and figures with no meaning attached.When data is processed (or given meaning) it produces information
- Therefore data is information
2
Q
Storing data
A
- Computers store data in a binary digit form
- A Binary digit (known as a bit) has a value of 1 or 0
- A nibble is represented as 8 bits
- A character (such as a letter or digit) is represented by 1 byte or (8 bits)
- Multiples of bytes are referred to as
- 1 kilobyte(Kb)=1024 bytes
- 1 megabyte(Mb)=1024 kilobytes
- 1 gigabyte (Gb)=1024 megabytes
- 1 terabyte (Tb)=1024 gigabytes
- These terms are used to describe computer memory capacity and the capacity of external storage devices
3
Q
Data types
A
Numeric:
- An integer number:
- can be a positive or negative whole number
- has no decimal or fractional parts
- Real numbers:
- include whole numbers (integers) and numbers with decimal/fractional parts
Date/Time:
- Long date is displayed as; Sunday,April 1,2018
- Medium date is displayed as 1-Apr-2018
- Short date is displayed as 01/04/18
- Long time is displayed as 13:26:34
- Medium time is displayed as 01:26PM
- Short time is displayed as 13:26
Character/String
- A character is a single letter or digit represented by the codes from the character set
- ASCII is a character set based on each character being represented uniquely by a single byte
- A string is textual data in the form of a sequence of characters
4
Q
Representing images
A
- A pixel is the smallest unit of a digital image that can be displayed and edited
- Each pixel can have its own individual colour and is stored as a series of binary digits
- Combing pixels together will produce a complete image
- The quality of an image is referred to as ‘image resolution’
- The greater the resolution,the greater the file size
- A typical JPEG image uses 24 bits to store a pixel
5
Q
Bitmap and vector images
A
- Bitmap graphics store details about every individual element (pixel) of the image
- Storing every pixel means the file size of a bitmap image can be very large
- A bitmap image can also be compressed,which reduces the file size
- Vector-based graphics store information about the components that make up an image
- Components are based on mathematical objects such as lines,curves and shapes
6
Q
Buffering and streaming a video
A
- Streaming allows a video to be viewed on a website without a time delay
- Using streaming means the user can start watching the video as it downloads in ‘real time’
- A buffer is part of the memory used to store a downloaded part of the video before watching it
- When the user is watching part of the video a buffer is used to download the next part of the video
- Buffering helps prevent possible disruptions if there are time delays in streaming while the video is playing
7
Q
Representing sound
A
Factors that affects sound quality:
-Sample rate-Number of audio sound samples captured per second to represent the sounds digitally
- Bit depth-The number of bits used for each sound sample
- The quantity of data measured in bits that is processed in a given amount of time
8
Q
Analogue to digital conversion
A
- An analogue signal is a continuous varying signal that represents a physical quantity
- Examples of analogue signals include sound waves and temperature
- An analogue to digital converter (ADC) will sample a signal at regular time intervals
- Samples are then converted to digital format
- The frequency at which samples are taken is known as the sample rate,measured in Hertz (Hz)
9
Q
Data portability
A
- Data portability is the ability to transfer data from one computer to another or form one software application to another without having to re-enter the data.
- This is made possible by using a range of file formats
10
Q
JPEG
A
Joint Photographic Expert Group files support the compression of images
11
Q
TIFF
A
Tagged Image File Formats store bitmapped images
12
Q
PNG
A
Portable Network Graphics allow data compression of bitmapped graphics
13
Q
PICT
A
The standard file format for apple graphics
14
Q
GIF
A
Graphics Interchange Format supports bitmapped image file format.Animated GIFs combine a series of GIF images and display them one after the other
15
Q
TXT
A
A plain text document that contains no text formatting
