Character Codes

Question 1

Describe BCD

Answer 1

BCD stands for Binary Coded Decimal
It is one of the early computer codes
It uses 6 bits to represent a symbol
It can represent 64 (2^6) different characters

Question 2

Describe EBCDIC

Answer 2

EBCDIC stands for Extended Binary Coded Decimal Interchange Code
It uses 8bits to represent a symbol
It can represent 256(2^8) different characters

Question 3

What are Zoned Decimal Numbers

Answer 3

ZDN are used to represent numeric values(positive, negative or unsigned) in EBCDIC

A sign indicator(C for plus, D for minus, and F for unsigned) is used in the zone position of the rightmost digit.

Zones for all other digits remain as F, the zone value for numeric characters in EBCDIC

In zoned format, there is only digit per byte.

Question 4

Describe ASCII

Answer 4

ASCII stands for American Standard Code for Information Interchange

ASCII is of two types - ASCII-7 and ASCII-8

ASCII-7 uses 7 bits to represent a symbol and can represent 128(2^7) characters

ASCII-8 uses 8 bits to represent a symbol and can represent 256(2^8) characters

First characters in ASCII-7 and ASCII-8 are the same.

Question 5

Why Unicode

Answer 5

No single encoding system supports all languages
Different encoding systems conflict

Question 6

Features of unicode

Answer 6

1. Provide a consistent way of encoding multilangual plain text.
2. Defines code for characters used in all major languages of the world
3. Defines codes for special character, mathematical symbols, technical symbols, and diacritics.
4. Capacity to encode as many as a million characters
5. Assigns each character a unique numeric value and name.

Question 7

Encoding forms

Answer 7

UTF-8, UTF-16, UTF-32

Question 8

How does sorting in EBCDIC work

Answer 8

Numeric characters are treated to be greater than alphabetic characters. Hence A1, 1A, 23

Question 9

How does sortin in ASCII work

Answer 9

Numeric charaters are treated to be less than alphabetic characters. Hence 1A,23,2