Binary Numbers and ASCII and EDCDIC Mrs. Cueni

Data Representation  Human speech is analog because it uses continuous signals (waves) that vary in strength and quality  Computers are digital – recognize two states ones and zeros, on of off  0 and 1 is called a bit Binary Digit  Smallest unit of information

Data representation  8 bits grouped together called a byte  Represent 256 individual characters  Numbers, uppercase, lowercase letters, punctuation marks  Based 2 numbering system

Coding Scheme  Two popular coding schemes ASCII – American Standard Code for Information Interchange ASCII – American Standard Code for Information Interchange EBCDIC – Extended Binary Coded Decimal Interchange Code EBCDIC – Extended Binary Coded Decimal Interchange Code Sufficient for English and Western Europe languages Sufficient for English and Western Europe languages Not large enough for Asian and other languages Not large enough for Asian and other languages

Coding Sheet ASCII numbers  is the number zero  The first four bits 0011 – identify as a number  The last four digits 0000 determines the number

Binary numbering system  Base 10  = 7  Base = = ,680,345

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Coding Sheet ASCII letters  is the letter A  The first two bits 01 – identify as a letter  The last six digits determines the letter as the first letter in the alphabet A

How did you do that?  is the letter Z  The first two bits 01 – identify as a letter  The last digits = =26  26 th letter Z =26

Letter order  1 st – A  2 nd – B  3 rd – C  4 th – D  5 th – E  6 th – F  7 th - G  8 th – H  9 th - I  10 th – J  11 th – K  12 th – L  13 th - M  14 th – N  15 th - O  16 th - P  17 th – Q  18 th – R  19 th – S  20 th – T  21 st – U  22 nd - V  23 rd – W  24 th – X  25 th – Y  26 th  26 th - Z

What are these letters?    

Coding Schemes  Make it possible to interact with computers  Does this very quickly without you realizing it  Type a character, the computer converts it and processes the data to something it understands  The software converts it back to something we understand

Unicode  Many languages use symbols called ideograms to represent multiple words or ideas  Unicode is a 16-bit code that has the capacity of representing more than 65,000 characters and symbols

Parity bit  Used by computers for error checking  Extremely rare  Computers are either odd- or even- parity  Total number of bits on must be even on even-parity computers or odd on odd- parity bit computers  9 bit pattern

Transferring data  When computers transfer data from one location to another it checks the sending data and the receiving data to make sure the parity bit is the same  An error is displayed if the parity doesn’t match

Hexadecimal  Used for communicating with programmers when a problem exists  0’s and 1’s can be difficult to read  Pass out Hexadecimal chart

Hexadecimal  Uses 16 symbols to represent values  Hex means six, deci means ten  Conversion between binary and hexadecimal is very efficient  The letter M is in binary  In Hexadecimal 4D  Divide binary number into two sections 0100 and 1101  Convert each section to the hex equivalent 0100 is a 4 and 1101 is letter D  A=10, B=11, C=12, D=13, E=14, F=16

Data Storage video  Progressive Insurance video on data storage

Binary Conversion Sheet  Complete in class the binary conversion sheet  Worth 26 points  Sources