Various Codes

7/27/2019 Various Codes

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CCooddeess

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Codes

Codes are groupings of symbols thatCodes are groupings of symbols thatare used for information exchange...are used for information exchange...

Examples ?

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Example: Morse code (1844)

Used in telegraphy today is a historical code4

Example: Braille code


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Example: Nautical flag code

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Example: Maya code-numbers

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Example: Maya code (?)

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Binary Codes

To represent a group of 2 distinctTo represent a group of 2 distinctelements in a binary code, it requireselements in a binary code, it requiresa minimum ofa minimum of nn--bitsbits..

n


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Example-1

It is known that a digital computer usesIt is known that a digital computer usestwo states that are represented with:two states that are represented with:thethe zerozero andand thethe oneone..

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Example-1 It is known that a digital computer uses two states thatIt is known that a digital computer uses two states that

are represented with:are represented with: thethe zerozero andand thethe oneone..

A group ofA group of fourfour different binary elementsdifferent binary elementscan be represented withcan be represented with 22 bits.bits.

0 0

0 1

1 0

1 1

4

2

0

1

2

3

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Example-2

A group of eight distinct elements can beA group of eight distinct elements can berepresented by 3 bits.represented by 3 bits.

00 00 00

00 00 11

00 11 00

00 11 11

11 00 00

11 00 11

11 11 00

11 11 11

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Special Codes


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Special Codes

88--44--22--11

BCDBCD

ExcessExcess--33

AikenAiken

22--outout--ofof--55

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Binary (8-4-2-1)

Weighted Code

84218421

00 00000000

11 00010001

22 00100010

33 00110011

44 01000100

55 01010101

66 01100110

77 01110111

88 10001000

99 10011001

1010 10101010

1111 10111011

1212 11001100

1313 11011101

1414 11101110

1515 11111111

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Binary Coded Decimal (BCD)

BCDBCD

00 00000000

11 00010001

22 00100010

33 00110011

44 01000100

55 01010101

66 01100110

77 01110111

88 1000100099 10011001

10101010

10111011

11001100

11011101

11101110

11111111

n

o

t

u

s

e

d

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Excess-3 (XS3)

XS3XS3

00000000

00010001

00100010

00 00110011

11 01000100

22 01010101

33 01100110

44 01110111

55 10001000

66 10011001

77 10101010

88 10111011

99 11001100

11011101

11101110

11111111


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Excess-3 (XS3)XS3XS3

00000000

00010001

00100010

00 00110011

11 01000100

22 01010101

33 01100110

44 01110111

55 10001000

66 10011001

77 10101010

88 10111011

99 11001100

11011101

11101110

11111111

Symmetric code

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Aiken codeAikenAiken

00 00000000

11 00010001

22 00100010

33 00110011

44 01000100

01010101

01100110

01110111

10001000

10011001

10101010

55 10111011

66 11001100

77 11011101

88 1110111099 11111111

2-4-2-1 Code

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Aiken code

AikenAiken

00 00000000

11 00010001

22 00100010

33 00110011

44 01000100

01010101

01100110

01110111

1000100010011001

10101010

55 10111011

66 11001100

77 11011101

88 11101110

99 11111111

Symmetric code

2-4-2-1 Code

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2-out-of-5

It is used as ErrorDetecting Code; natural even parity

VeryPracticalCode


00 1100011000

11 0001100011

22 0010100101

33 0011000110

44 0100101001

55 0101001010

66 0110001100

77 1000110001

88 1001010010

99 1010010100


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2-out-of-5


00 1100011000

11 0001100011

22 0010100101

33 0011000110

44 0100101001

55 0101001010

66 0110001100

77 1000110001

88 1001010010

99 1010010100Except for the zero (0)which is decimal 24. The

rest of the code followsthe weights: 74210 22

2-out-of-5

This code is used by theU.S. Postal Service---- Zip Code

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The first and last bars are the frame bars, used for aligningthe scanner which reads the bar-code. The last digits areused for error correction (checksum)..

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0 7 0 2 4 4 9 0 5

The first and last bars are the frame bars, used for aligningthe scanner which reads the bar-code. The last digits areused for error correction (checksum)..


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Bar Code based codes

11--D codesD codes

22--D codesD codes

PracticalCodes

1-D and 2-D Codes will not be included in the exams 26

1-D codes

Code 39 = Code 3Code 39 = Code 3--ofof--9; alphanumeric (full ASCII)9; alphanumeric (full ASCII)bar code;bar code;applications in inventory, asset tracking, ID badgesapplications in inventory, asset tracking, ID badges

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1-D codes


Interleaved 2 of 5 ; NumericInterleaved 2 of 5 ; Numeric--only bar code,only bar code,industrial applications, carton labeling, laboratoryindustrial applications, carton labeling, laboratory

usesuses

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1-D codes


Interleaved 2 of 5 ; NumericInterleaved 2 of 5 ; Numeric--only bar code,only bar code,industrial applications, carton labeling, laboratoryindustrial applications, carton labeling, laboratory

usesuses UPC (Universal Product Code), Numeric Bar code;UPC (Universal Product Code), Numeric Bar code;

used in retail product labeling.used in retail product labeling.


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1-D codes


Interleaved 2 of 5 ; NumericInterleaved 2 of 5 ; Numeric--only bar code,only bar code,industrial applications, carton labeling, laboratoryindustrial applications, carton labeling, laboratoryusesuses

UPC (Universal Product Code), Numeric Bar code;UPC (Universal Product Code), Numeric Bar code;used in retail product labeling.used in retail product labeling.

Code 128Code 128 Alphanumeric (full ASCII);Alphanumeric (full ASCII);

applications in Shipping, Warehouse management.applications in Shipping, Warehouse management.30

2-D code

--PDF417;PDF417;applications web postage stamp..applications web postage stamp..

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PDF417

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PDF417


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Alphanumeric codes

Used to print, teletype or view informationUsed to print, teletype or view informationor other means of human alphaor other means of human alpha--numericnumericcommunication.communication.

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Alphanumeric codes

Used to print, teletype or view informationUsed to print, teletype or view informationor other means of human alphaor other means of human alpha--numericnumericcommunication.communication.

EBCIDIC

ASCII

UniCode

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EBCIDIC

EBCIDICEBCIDIC ((EExtendedxtended BCD IBCD Interchangenterchange CCode):ode):

8 bits = 256 characters.8 bits = 256 characters.

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ASCII

EBCIDIC (Extended BCD Interchange Code):EBCIDIC (Extended BCD Interchange Code):8 bits = 256 characters.8 bits = 256 characters.

ASCII (AASCII (Americanmerican SStandardtandard CCodeode forforIInformationnformation IInterchangenterchange):):

7 bits = 128 characters (now Super7 bits = 128 characters (now SuperASCII use all 8ASCII use all 8--bits ).bits ).


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ASCII

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Unicode

EBCIDIC (Extended BCD Interchange Code):EBCIDIC (Extended BCD Interchange Code):8 bits = 256 characters.8 bits = 256 characters.

ASCII (American Standard Code forASCII (American Standard Code forInformation Interchange):Information Interchange):7 bits = 128 characters.7 bits = 128 characters.

Unicode (New standard for 16Unicode (New standard for 16 bitbitalphanumeric codes)alphanumeric codes)

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A useful code is the Gray

Gray code is of cyclic nature having theGray code is of cyclic nature having thefollowing property:following property:

From one number to the next, the Gray codeFrom one number to the next, the Gray codechanges only one bitchanges only one bit

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Bit changes

Gray code is of cyclic nature having the following property:Gray code is of cyclic nature having the following property:

From one number to the next, the Gray codeFrom one number to the next, the Gray code changes onlychanges onlyone bitone bit

Binary

00

01 1

10 2

11 1

Gray

00

01 1

11 1

10 1


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Gray Code

The Gray code is used for labeling KarnaughThe Gray code is used for labeling Karnaughmaps for logic circuit simplification, formaps for logic circuit simplification, forrouting in parallel computer systems,routing in parallel computer systems,etc..etc..

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Gray Codes

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Gray Codes

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Gray Codes


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Binary and BCD numbers

Bits obtained from conversion, ofBits obtained from conversion, ofbinary numbers, are binary digitsbinary numbers, are binary digits

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Binary and BCD numbers

Bits obtained from conversion, ofBits obtained from conversion, ofbinary numbers, are binary digitsbinary numbers, are binary digits

Bits obtained from coding (BCD) areBits obtained from coding (BCD) arecombinations of 1s and 0s arrangedcombinations of 1s and 0s arrangedaccording to the rules of the codeaccording to the rules of the code(BCD).(BCD).

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Example-1

(13)(13)1010 = (1101)= (1101)22,,

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Example-1

(13)(13)1010 = (1101)= (1101)22,,

butbut,,

(13)(13)1010 = (0001 0011)= (0001 0011)BCDBCD

(1 3)(1 3)1010


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Example-2

(7)(7)1010 = (111)= (111)22,,

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Example-2

(7)(7)1010 = (111)= (111)22,,

but,but,

(0111)(0111)BCDBCD

771010

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Another Example

(15)(15)1010 = (1111)= (1111)22,,

but,but,

(15)(15)1010 = (0001 0101)= (0001 0101)BCDBCD

(1 5)(1 5)1010

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Binary & BCD

((1515))1010


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Binary & BCD

((1515))1010

((11111111))22 ()()BCDBCD

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Binary & BCD

((1515))1010

((11111111))22 ((00010001 01010101))BCDBCD

END

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New codes

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Code-A

AA

00 00000000

11 00010001

22 00100010

00110011

01000100

33 01010101

44 01100110

01110111

1000100055 10011001

66 10101010

10111011

11001100

77 11011101

88 11101110

99 11111111

Symmetric code


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Code-BBB

00 00000000

11 00010001

22 00100010

00110011

01000100

01010101

33 01100110

44 01110111

55 10001000

66 10011001

10101010

10111011

11001100

77 11011101

88 1110111099 11111111

Symmetric code

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Code-CCC

00 00000000

11 00010001

22 00100010

33 00110011

01000100

01010101

01100110

44 01110111

55 10001000

10011001

10101010

10111011

66 11001100

77 11011101

88 1110111099 11111111

Symmetric code

Documents

Various Codes