Bits and bytes
This presentation is the property of its rightful owner.
Sponsored Links
1 / 8

Bits and Bytes PowerPoint PPT Presentation


  • 57 Views
  • Uploaded on
  • Presentation posted in: General

Bits and Bytes. ASCII/EBCDIC. There was one other problem with bytes: Compatibility. Given the binary sequences:. Manufact. #1:. Manufact. #2:. Manufact. #3:. A. 0. +. 0000000. B. 1. -. 0000001. C. 2. *. 0000010. D. 3. ?. 0000011.   .   .   .

Download Presentation

Bits and Bytes

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Bits and bytes

Bits and Bytes

ASCII/EBCDIC

  • There was one other problem with bytes:

  • Compatibility

Given the binary sequences:

Manufact.

#1:

Manufact.

#2:

Manufact.

#3:

A

0

+

0000000

B

1

-

0000001

C

2

*

0000010

D

3

?

0000011

  

  

  

  

6

v

TAB

1111110

7

x

CR

1111101

8

y

LF

1111110

9

z

FF

1111111

Manufacturers Interpreted them differently


Bits and bytes1

Bits and Bytes

Which is the Correct Interpretation???

Each is equally Correct

  • 0000010 Could be either a ‘C’ OR a ‘2’

  • The letter ‘C’ Could be pronounced either ‘cee’ OR ‘ess’

What’s the Solution ???

ASCII

The American Standard Code for InformationInterchange


Bits and bytes2

Bits and Bytes

Sample ASCII Codes:

Binary Sequence

Character

Description .

Value

0000000

0

NULL

NULL/Tape feed

  

  

  

  

0000111

BEL

Rings Bell

7

8

BS

Back Space

0001000

  

  

  

  

0001101

13

CR

Carriage Return

  

  

  

  

0011011

27

ESC

Escape

  

  

  

  

0100000

32

SP

Space

  

  

  

  

0110000

48

0

Zero

0110001

49

1

One

  

  

  

  

1000001

65

A

Capital ‘A’

1000010

66

B

Capital ‘B’

  

  

  

  

1100001

97

a

Lower Case ‘a’

1100010

98

b

Lower Case ‘b’


Bits and bytes3

Bits and Bytes

A Preview of Things to Come:

  • For the first Exam Memorizethe Numeric Values for:

  • NULL Value: 0

  • BEL (Ring The Bell)Value: 7

  • BS (Backspace)Value: 8

  • CR (Carriage Return)Value: 13

  • ESC (Escape)Value: 27

  • SP (Space)Value: 32

  • The digits (0, 1, …, 9)

  • NOTE: The Digit 0 (zero) has the value:48

  • The Uppercase Alphabet

  • NOTE: The Character ‘A’ has the value:65

  • The Lowercase Alphabet

  • NOTE: The Character ‘a’ has the value:97


Bits and bytes4

Bits and Bytes

Are We limited to only 128 (= 27) characters ??

Yes and no:

  • The STANDARD ASCII Character Set Consists of 128 Characters (as given in Addendum 1.1)

There is an EXTENDED ASCII Character set which uses ALL 8-bits (1-byte) available (parity is NOT an issue)

  • The extended ASCII Character set consists of 256 (= 28) characters (See Addendum 1.2)

  • The Majority of the characters included in the extended ASCII character set are extensions of the Greco-Roman Alphabet (e.g., ß, Ü, å) or ‘graphics’ characters (e.g., )


Bits and bytes5

Bits and Bytes

What does the term ‘ASCII file’ Mean ??

An ASCII File assumes that every 8-bits (1-byte) in the file are grouped together according to the ASCII tables

Aren’t ALL Files ASCII Files ??

NO - As we will see later, not all data is stored according to ASCII formats

That Helps (sort-of) to explain why when we display non-ASCII files we sometimes get characters such as ,  , , , , and 


Bits and bytes6

Bits and Bytes

Do ALL computers use ASCII to Represent Symbols???

NO - Although most do.

IBM had the first Coding Scheme (dating back to 1880)

EBCDIC

ExtendedBinaryCodedDecimalInterchangeCode

EBCDIC is still used in IBM Mainframes and to store data on large reel-to-reel Tape Drives


Bits and bytes

This Concludes The Slides for this Section

Choose an Option:

 Repeat Slides for this Section

 Go To Slide Index For Chapter 1

 Go To Slide Index For Chapter 2

 Go To Slide Index For Textbook

 Go To Home Page


  • Login