COMPUTER SCIENCE
CHARACTER ENCODING SYSTEM
|BCD
Binary coded decimal (BCD) is a system of writing numerals that assigns a four-digit binary code to each digit 0 through 9 in a decimal (base-10) numeral. The four-bit BCD code for any particular single base-10 digit is its representation in binary notation. Itsone of the early computer codes. It uses 6 BITs to represent symbol. It can represent up to 64 different characters.
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EBCDIC
Extended Binary Coded Decimal Interchange Code (EBCDIC) is an eight-bit character encoding used mainly on IBM mainframe and IBM midrange computer operating systems. EBCDIC descended from the code used with punched cards and the corresponding six bit binary-coded decimal code used with most of IBM's computer peripherals of the late 1950s and early 1960s.
It uses uses 8 BITs to represent symbol and can represent up to 256 different characters.
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ASCII
American Standard Code for Information Interchange. ASCII codes represent text in computers, communications equipment, and other devices that use text. Its of two tyoes: Viz:
ASCII-7-This uses 7 BITs to represent a symbol and can represent up to 128 different characters.
ASCII-8- This uses 8 BITs to represent a symbol and can represent up to 256 different characters.
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UNICODE
What is the unicode?-The Unicode Standard is the universal character encoding standard used for representation of text for computer processing. Unicode provides a consistent way of encoding multilingual plain text making it easier to exchange text files internationally which is much better than ASCII.
What is meant by UTF 8?- UTF stands for Unicode Transformation Format. The '8' means it uses 8-bit blocks to represent a character. The number of blocks needed to represent a character varies from 1 to 4.
How many bits are in a character? - A Unicode character in UTF-8 encoding is between 8 bits (1 byte) and 32 bits (4 bytes).
How many characters can be represented in Unicode?-Unicode allows for 17 planes, each of 65,536 possible characters (or 'code points'). This gives a total of 1,114,112 possible characters (i.e 65536 x 17). At present, only about 10% of this space has been allocated.
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