© 2001, Penn State University Encoding on the Internet Elizabeth J. Pyatt CETS

© 2001, Penn State University Computers Do Numbers All data on computers are ultimately stored as numbers Letters are assigned numbers via an encoding sytem Numbers in the encoding system determine the alphabetical order of the letters Keyboards input a number which correponds to that letter

© 2001, Penn State University ASCII Encoding ASCII - American Standard Code for Information Exhange Invented in the 1960s Limited to 128 (2 7 ) characters (English only) ASCII encoding on all modern computers ASCII encodes letters, digits, punctuation and the blank space character Distinguishes capital letters from lower case

© 2001, Penn State University ASCII Chart (Excel)

© 2001, Penn State University First Steps Beyond ASCII Vendors add an additional 128 characters for 256 total characters ( or 2 8 “8-bit”) Characters #0-127 = ASCII Characters # = non-English letters and punctuation Each accented letter (e.g. á,â or Á) is a separate character. Multiple vendors = multiple standards

© 2001, Penn State University ISO / Latin 1 Internet standard for English and Western European Languages is ISO ISO = International Organization of Standards 8859 = encoding standard 1 = 1st one registered at ISO Latin / Roman = English alphabet Almost identical to Windows-1252 encoding Differs from “MacRoman” on Macintosh

© 2001, Penn State University Latin-1 vs. Mac Roman (GIF)

© 2001, Penn State University Encoding Non-Roman Scripts Alternate encodings developed for other scripts like Russian, Arabic, Greek, Hebrew Template is: –Character #0-127=ASCII –Character # =Non-Roman script Some scripts also developed multiple encodings, typically an ISO version and a Windows version (e.g.Hebrew = ISO or Windows-1255)

© 2001, Penn State University Encoding Schemes

© 2001, Penn State University 16 Bit and Beyond Chinese, Japanese and Korean have more than 256 characters 16-Bit encodings with 2 16 or 65,536 characters developed Unicode, which attempts to combine all modern scripts into one super encoding block, is currently being developed Increasing Unicode support on Windows and Macintosh, but still limited in application

© 2001, Penn State University How browsers read a site Web site specifies encoding to browser Browser matches encoding with the right font on your machine Browser displays the appropriate characters (English and non-English)

© 2001, Penn State University How to mess up the browser Web site doesn’t specify encoding, so browser stays on default (usually Latin-1) Web site specifies font not on user’s machine Font doesn’t match encoding Font doesn’t have all the right characters (e.g. € (Euro currency symbol))

© 2001, Penn State University Keyboards & Fonts Normal fonts (e.g. Times, Arial) match the character to its ASCII/Latin-1 number based on the keyboard “Dingbat Fonts” (e.g. Symbol, Wingdings) do not match the character to the ASCII Code Most keyboards still access only 128 characters at time (Mac can do 256) Therefore, older non-English script fonts (e.g. Symbol) do not always match script encoding

© 2001, Penn State University Where to get good fonts Microsoft provides free, properly encoded, fonts with Windows NT and Windows 2000 Apple provides free, properly encoded fonts via its Language Kits (free with System 9) Third party fonts are available (but can be glitchy)