**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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