Paper 2 - Data Representation Flashcards
Logic Gates:
Special Circuits built into computer chips, receive binary data and perform a Boolean Operation.
Not Gate:
Outputs opposite input
And Gate:
If both inputs are 1 the output is 1 otherwise it is always 0
Or Gate:
if one or more inputs are 1 then the output is 1 otherwise the output is 0
Parity Bits
The check digit used for binary data; The check digit is added to make the binary either have an even or odd number of 1’s, if one bit is read incorrectly the computer will pick out the error. If two bits are read incorrectly then no error will be detected.
What is Denary?
A number system with ten digits (1-9)
What is Binary?
Only uses two different digits- also known as base-2.
Right to Left values go up by powers of 2.
What is left shift?
Multiplying Binary by 2 to the a the power of spaces moved.
What is right shift?
Dividing Binary by 2 to the power of spaces moved.
What are Alphanumeric characters?
Used to make words and strings; Computers are unable to process them and-so they are represented by binary in character sets.
ASCII:
7- bit binary code representing 128 different code; each character fits into 1 byte.
Extended ASCII:
8-bit binary code representing up to 256 characters the first 128 being the original ASCII. Useful for European languages with unique accents.
Unicode:
Covers every possible character that could be written; 16-bit and 32-bit codes. Unicode covers all major languages, suchas Greek, Russian and Chinese.
Bitmap Images are made of _____?
Pixels- colours represented by binary code, the larger the range of colours the larger the bit count of a pixel.
Number of bits per pixel is called _____.
colour depth
Total number of colours = _______
2^ colour depth
What is the resolution?
The density of pixels in an area, commonly measured in dots per inch (dpi)
Increasing resolution or colour depth increases ______.
File size and image quality.
What is Metadata?
Information stored to the file including the image’s file format, height, width, colour depth and resolution.
What is an Analogue signal?
A continually changing piece of audible data.
Analogue data needs to be converted into _____
Digital Data, does this by the process of sampling.
How is sampling used for audio?
Amplitude is measured at regular intervals, only taking values dependent on bit rate. The data loses data in the sampling process, however this can be mitigated by more regularly taking samples.
Sampling Frequency is _____
Samples taken per second.
Sample size is _____
Bits available for each sample.
Bit rate is _____
Number of Bits per second of audio.
Equation for Bit Rate?
Bit Rate = Sampling frequency x Sample Size.
Uses of compressing data?
Less storage space used; Quicker to stream or download; allows web pages to more quickly load and abiding data restrictions set by emails.
Lossy Compression:
Pros: Greatly reduced file size. Takes up less bandwidth. Commonly used. Loss in quality usually unnoticeable.
Cons: Loses data; can’t be used on text or software files.
Lossless Compression:
Pros: No reduction in quality, can be decompressed; can be used on files and text.
Cons: Only slight reduction in file size.
what is a Character Set:
A collection of characters a computer recognises from their binary representation.
