Specification Journal 011
3.5.5 Information Coding Systems
For this specification point the following areas are covered: (3.5.5)
 3.5.5.1 Character form of a decimal digit
 3.5.5.2 ASCII and Unicode
 3.5.5.3 Error Checking
1.1 Key terms to define
Write a detail definition of each term given below. Look into the technical aspects of each key
word.
Term
Character Code
ASCII
Unicode
Parity Bit
Majority Voting
Check digits
Definition
Questions to complete
1.2 ASCII and Unicode
1) How would the word Cat be stored?
2) Using the Unicode UTF-16 system, how much memory would be used for the word mouse?
1.3 Error correction
1) What would be the parity bit value for 0010110 using odd parity?
2) Assuming 010 011 110 010 000 110 111 100 is received, what value would be accepted using
majority voting?
3) What is Checksum method of error checking?
4) Investigate the Modulo 10 system and use it on a book ISBN number.
5) Describe how the methods work and what their limitations are – use examples to illustrate your
points.
a) Parity Bit
b) Majority voting
c) Check digits
6) Investigate another error checking method or actual error correction method.
Extension
Create a C# program that simulates the error checking methods of
a) Parity bit checking
b) Majority voting check
c) Modulo 10