Information Coding Systems Flashcards
What is a character set?
A character set is a list of all the characters accessible to a computer system
What is ASCII?
ASCII is a seven-bit character set which offers 128 different characters. Some of these characters are used for controlling peripherals.
What is Unicode?
Unicode is a 16-bit character set which offers 65,536 different characters. It includes the characters for any writing system in the world
What is Even parity?
Even parity is where the number of 1s is counted and if the number of 1s is odd then the parity bit is set to 1.
-If the number of 1s is even, the parity bit is set to 0
What is Odd parity?
Odd parity is where the numbers of 1s is counted and if the number of 1s is even then the parity bit is set to 1.
-If the number of 1s counted is odd the parity bit is set to 0.
What is a majority vote?
The parity bit approach can only detect errors in data transmission, but the majority vote concept can be used for error correction.
How does majority voting work?
With majority voting, each bit is sent three times and checked each time. If it is the same there is no error, but if it is different on one occasion there is an error, in which case the majority of two will determine the correct bit.
What is a disadvantage of majority vote?
Main disadvantage of majority vote correction method is three times the volume of data needs to be transmitted.
What is a checksum?
A checksum is an error detection method where the number of bits transmitted in a message is counted; this checksum is compared with a count of the data received to check the integrity of the data transmission
What is a check digit?
A check digit is added to binary data to check that the data is accurate; this is an approach used by stores to check that the bar code printed on an item of shopping has been correctly entered into a computer.
