In this chapter you will learn about:
Computer codes: representation of data in binary
Most commonly used computer codes
Collating sequence
Data Types
Numeric information consists of solely numbers zero, 1, 2, …, 9
Alphabetic information consists of solely the letters A, B, C, …, Z, in each majuscule and small, and blank character
Alphanumeric information may be a string of symbols wherever a logo could also be one in every of the letters A, B, C, …, Z, in either majuscule or small, or one in every of the digits zero, 1,2,…,9, or special character,suchas+-*/, .( ) = etc.
Computer codes square measure used for the inner illustration of information in computers
As computers use binary numbers for internal information illustration, pc codes use binary writing schemes
In binary writing, each image that seems within the information is drawn by a gaggle of bits
The cluster of bits accustomed represent a logo is named a computer memory unit
As most recent writing schemes use eight bits to represent a logo, the term computer memory unit is commonly accustomed mean a gaggle of eight bits
Commonly used pc codes square measure BCD, EBCDIC, and ASCII.
BCD
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 (26) different characters
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Example
Show the binary digits used to record the word BASE in BCD
Solution:
B = 110010 in BCD binary notation A = 110001 in BCD binary notation S = 010010 in BCD binary notation E = 110101 in BCD binary notation
So the binary digits
will record the word BASE in BCD
Example
Using octal notation, show BCD coding for the word DIGIT
Solution:
D = 64 in BCD octal notation I = 71 in BCD octal notation G = 67 in BCD octal notation I = 71 in BCD octal notation T = 23 in BCD octal notation
Hence, BCD coding for the word DIGIT in octal notation will be
will record the word BASE in BCD
EBCDIC stands for Extended Binary Coded Decimal Interchange Code
It uses 8 bits to represent a symbol
It can represent 256 (2)8 different characters
Zoned Decimal Numbers
Zoned decimal numbers square measure wont to represent numeric values (positive, negative, or unsigned) in EBCDIC.
A sign indicator (C for and, D for minus, and F for unsigned) is employed within the zone position of the right digit Zones for all alternative digits stay as F, the zone price for numeric characters in EBCDIC.
In zoned format, there’s just one digit per computer memory unit.
Examples Zoned Decimal Numbers
Packed Decimal Numbers
Packed decimal numbers square measure fashioned from zoned decimal numbers within the following manner:
Step 1: The zone half and also the digit 1/2 the right computer memory unit square measure reversed
Step 2: All remaining zones square measure born out
Packed decimal format needs a fewer range of bytes than the zoned decimal format for representing a variety
Numbers delineated in the packed decimal format are often used for arithmetic operations
Examples of Conversion of Zoned Decimal Numbers to Packed Decimal Format
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