% ae
\newcount\isdos\isdos=0
\newcount\ismac\ismac=0
%   x84 = 8*16 + 4 = 128 + 4 = 132 dezimal
\catcode`\^^84=\active \def ^^84{\"a\isdos=1}   %  dos ae == utf8 Ae % siehe bei utf8 Ae 
\catcode`\^^cc=\active \def ^^cc{\"a}   %  unix
\catcode`\^^e4=\active \def ^^e4{\"a}   %  win   14*16 + 4 = 224 + 4 = 228
\catcode`\^^8a=\active \def ^^8a{\"a\isdos=0\ismac=1}   %  mac
% oe
\catcode`\^^94=\active \def ^^94{\"o\isdos=1}   %  dos
\catcode`\^^ce=\active \def ^^ce{\"o}   %  unix
\catcode`\^^f6=\active \def ^^f6{\"o}   %  win
\catcode`\^^9a=\active \def ^^9a{\ifodd\isdos{\"U}\else{\"o\ismac=1}\fi}   %  mac oe  ==  dos Ue
% ue
\catcode`\^^81=\active \def ^^81{\"u\isdos=1}   %  dos
\catcode`\^^cf=\active \def ^^cf{\"u}   %  unix
\catcode`\^^fc=\active \def ^^fc{\"u}   %  win
%\catcode`\^^9f=\active \def ^^9f{\"u}   %  mac ue == utf8 sz % siehe bei utf8 sz
% Ae
\catcode`\^^8e=\active \def ^^8e{\"A\isdos=1}   %  dos    8*16+14=128+14=142
\catcode`\^^d8=\active \def ^^d8{\"A}   %  unix
\catcode`\^^c4=\active \def ^^c4{\"A}   %  win
\catcode`\^^80=\active \def ^^80{\"A\isdos=0\ismac=1}   %  mac
% Oe
\catcode`\^^99=\active \def ^^99{\"O\isdos=1}   %  dos
\catcode`\^^da=\active \def ^^da{\"O}   %  unix
\catcode`\^^d6=\active \def ^^d6{\"O}   %  win
\catcode`\^^85=\active \def ^^85{\"O\isdos=0\ismac=1}   %  mac
% Ue
%\catcode`\^^9a=\active \def ^^9a{\"U}   %  dos Ue == mac oe % siehe bei mac oe
\catcode`\^^db=\active \def ^^db{\"U}   %  unix
\catcode`\^^dc=\active \def ^^dc{\"U}   %  win
\catcode`\^^86=\active \def ^^86{\"U\isdos=0\ismac=1}   %  mac
% SZ
\catcode`\^^e1=\active \def ^^e1{{\ss}\isdos=1} %  dos
\catcode`\^^de=\active \def ^^de{{\ss}} %  unix
\catcode`\^^df=\active \def ^^df{{\ss}} %  win
\catcode`\^^a7=\active \def ^^a7{{\ss}\isdos=0\ismac=1} %  mac

% statt: \usepackage[utf8]{inputenc}:
\newcommand{\ManageUtfUmlaute}[1]{#1} % utf8-Mehr-Zeichen-Umlaute umsetzen
\catcode`\^^c3=\active \def ^^c3{\ManageUtfUmlaute{}}
\catcode`\^^a4=\active \def ^^a4{\"a\ismac=0\typeout{utfae}}
\catcode`\^^b6=\active \def ^^b6{\"o\ismac=0}
\catcode`\^^bc=\active \def ^^bc{\"u\ismac=0}
\catcode`\^^84=\active \def ^^84{\ifodd\isdos{\"a}\else{\"A\ismac=0}\fi} %% uft8 Ae == dos ae
\catcode`\^^96=\active \def ^^96{\"O\ismac=0}
\catcode`\^^9c=\active \def ^^9c{\"U\ismac=0}
                                               %% utf8 sz == macintosh ue
\catcode`\^^9f=\active \def ^^9f{\ifodd\ismac{\"u}\else{{\ss}}\fi} 

\newcommand{\MAC}{\ismac=1\isdos=0}\newcommand{\DOS}{\ismac=0\isdos=1}
\typeout{}
\typeout{If the first ue-Umlaut is an sz character put in a call of macro >MAC<!}
\typeout{If the first ae-Umlaut is an Ae character put in a call of macro >DOS<!}
\typeout{}
% \DOS \typeout{\ifodd\isdos{isdos == 1}\else{isdos == 0}\fi}
% \MAC \typeout{\ifodd\isdos{ismac == 1}\else{ismac == 0}\fi}
