\chardef\escape=0
\chardef\letter=11
\chardef\other=12
%\chardef\active=13              % is defined in Plain already

\chardef\atcode=\catcode`\@
\chardef\uscode=\catcode`\_

\catcode`\@=\letter
\catcode`\_=\letter
\font\tentex=cmtex10            % typewriter extended ASCII 10pt
\let\ttex=\tentex               % only for PLAIN with base size 10pt

\def\setup_verbatim{%
   \def\do##1{\catcode`##1\other}\dospecials
   \parskip\z@skip \parindent\z@
   \obeylines \obeyspaces \obeytabs \frenchspacing
   \ttex
   }

\let\tab=\space
\begingroup
   \catcode`\^^I=\active%       % Attention: no tabs!
   \gdef\obeytabs{\catcode`\^^I=\active\def^^I{\tab}}
   \global\let^^I=\tab%         % if an active tab appears in a \write
\endgroup
\let\origvert=|
\chardef\vbar=`\|

\catcode`\|=\active

\def|{%
   \leavevmode
   \hbox\bgroup
      \let\par\space \setup_verbatim
      \let|\egroup
   }
\newif\if@print

\def\beginprog{%
   \endgraf
   \bigbreak
   \begingroup
      \setup_verbatim \catcode`\|\other
      \@printtrue
      \ignore_rest_line
   }
\let\end_verbatim=\endgroup             % internal command !
\begingroup
   \obeylines%          % ^^M is active! ==> every line must end with %
   \gdef\ignore_rest_line#1^^M{\set_next_line}%
   \gdef\set_next_line#1^^M{\do_set{#1}}%
\endgroup

\def\do_set#1{%
   \endgraf
   \check_print{#1}%
   \if@print  \indent \print_char#1\end_line\end_line
   \else  \let\set_next_line\end_verbatim
   \fi
   \set_next_line
   }
\let\end_line=\relax
\begingroup
\obeyspaces\obeytabs
\gdef\check_print#1{\cut_at_tab#1^^I\end_line}
\gdef\cut_at_tab#1^^I#2\end_line{\check_first_part#1 \end_line}% blank !
\gdef\check_first_part#1 #2\end_line{\do_check{#1}}
\endgroup
\def\do_check#1{%
   \def\@line{#1}%
   \ifx \@line\@endverbatim  \@printfalse
   \fi
   }

{\catcode`\|=\escape  \catcode`\\=\other % | is temporary escape char
   |gdef|@endverbatim{\endprog}          % sample line
}                                        % here \endgroup can't be used
\newcount\char_count  \char_count\@ne

\def\print_char#1#2\end_line{%
   \print_first_char{#1}%
   \print_rest_of_line{#2}%
   }
{\obeytabs\gdef\@tab{^^I}}

\def\print_first_char#1{%
   \def\@char{#1}%
   \advance \char_count\@ne
   \ifx \@char\@tab  \print_tab
   \else  \@char
   \fi
   }
\newcount\count_mod_viii
\def\mod_viii#1{%
   \count@ #1\relax  \count_mod_viii\count@
   \divide \count@ 8\relax
   \multiply \count@ 8\relax
   \advance \count_mod_viii -\count@
   }
\def\print_tab{%
   \loop  \space \mod_viii\char_count
      \ifnum \count_mod_viii>\z@
         \advance \char_count\@ne
   \repeat
   }
\def\print_rest_of_line#1{%
   \def\@line{#1}%
   \ifx \@line\empty  \char_count\@ne
        \def\next##1\end_line{\relax}%
   \else  \let\next\print_char
   \fi
   \next#1\end_line
   }
\newcount\sectno  \sectno=\@ne
\def\chap#1.{%
   \mark{\number\sectno}
   \endgraf
   \vfill\eject
   \def\rhead{\uppercase{\ignorespaces#1}} % define running headline
   \message{*\number\sectno} % progress report
   \let\Z=\let % now you can \send the control sequence \Z
   \edef\next{\write\cont{\Z{#1}{\number\sectno}{\the\pageno}}}\next % to contents file
   \noindent {\bf \number\sectno.\quad #1.}%
   \advance \sectno\@ne
   \endgraf
   \medskip  \nobreak
   \everypar{%
      \setbox0\lastbox
      \global\everypar{}%
      }%
   }
\def\sect{%
   \mark{\number\sectno}
   \endgraf
   \vskip 2pc plus 1pc minus 6dd  \goodbreak
   \noindent {\bf \number\sectno.}\advance \sectno\@ne
   \quad \ignorespaces
   }
\parskip 0pt % no stretch between paragraphs
\parindent 1em % for paragraphs and for the first line of Pascal text
\font\eightrm=cmr8
\font\sc=cmcsc10 % this IS a caps-and-small-caps font!
\let\mainfont=\tenrm
\font\titlefont=cmr7 scaled\magstep4 % title on the contents page
\font\ttitlefont=cmtt10 scaled\magstep2 % typewriter type in title
%\font\tentex=cmtex10 % TeX extended character set (used in strings)
        % already defined above
\fontdimen7\tentex=0pt % no extra space after punctuation
\def\\#1{\hbox{\it#1\/\kern.05em}} % italic type for identifiers
\def\|#1{\hbox{$#1$}} % one-letter identifiers look a bit better this way
\def\{\hbox{\bf#1\/}} % boldface type for reserved words
\def\.#1{\hbox{\tentex % typewriter type for strings
  \let\\=\BS % backslash in a string
  \let\'=\RQ % right quote in a string
  \let\`=\LQ % left quote in a string
  \let\{=\LB % left brace in a string
  \let\}=\RB % right brace in a string
  \let\~=\TL % tilde in a string
  \let\ =\SP % space in a string
  \let\_=\UL % underline in a string
  \let\&=\AM % ampersand in a string
  #1}}
\def\#{\hbox{\tt\char`\#}} % parameter sign
\def\${\hbox{\tt\char`\$}} % dollar sign
\def\%{\hbox{\tt\char`\%}} % percent sign
\def\^{\ifmmode\mathchar"222 \else\char`^ \fi} % pointer or hat
% circumflex accents can be obtained from \^^D instead of \^
\def\AT!{@} % at sign for control text

\chardef\AM=`\& % ampersand character in a string
\chardef\BS=`\\ % backslash in a string
\chardef\LB=`\{ % left brace in a string
\def\LQ{{\tt\char'22}} % left quote in a string
\chardef\RB=`\} % right brace in a string
\def\RQ{{\tt\char'23}} % right quote in a string
\def\SP{{\tt\char`\ }} % (visible) space in a string
\chardef\TL=`\~ % tilde in a string
\chardef\UL=`\_ % underline character in a string
\newdimen\pagewidth \pagewidth=6.5in % the width of each page
\newdimen\pageheight \pageheight=8.7in % the height of each page
\newdimen\fullpageheight \fullpageheight=9in % page height including headlines
\newdimen\pageshift \pageshift=0in % shift righthand pages wrt lefthand ones
\def\magnify#1{\mag=#1\pagewidth=6.5truein\pageheight=8.7truein
  \fullpageheight=9truein\setpage}
\def\setpage{\hsize\pagewidth\vsize\pageheight} % use after changing page size
\def\lheader{\mainfont\the\pageno\eightrm\qquad\rhead\hfill\title\qquad
  \tensy x\mainfont\topmark} % top line on left-hand pages
\def\rheader{\tensy x\mainfont\topmark\eightrm\qquad\title\hfill\rhead
  \qquad\mainfont\the\pageno} % top line on right-hand pages
\def\page{\box255 }
\def\normaloutput#1#2#3{\ifodd\pageno\hoffset=\pageshift\fi
  \shipout\vbox{
    \vbox to\fullpageheight{
      \iftitle\global\titlefalse
      \else\hbox to\pagewidth{\vbox to10pt{}\ifodd\pageno #3\else#2\fi}\fi
      \vfill#1}} % parameter #1 is the page itself
  \global\advance\pageno by1}

\def\rhead{\.{DOCMAC} OUTPUT} % this running head is reset by starred sections
\def\title{} % an optional title can be set by the user
\def\contentspagenumber{0} % default page number for table of contents
\newif\iftitle

\def\topofcontents{\centerline{\titlefont\title}
  \vfill} % this material will start the table of contents page
\def\botofcontents{\vfill} % this material will end the table of contents page
\def\contentsfile{\jobname.toc} % file that gets table of contents info
\def\readcontents{\expandafter\input \contentsfile}

\newwrite\cont
\output{\setbox0=\page % the first page is garbage
  \openout\cont=\contentsfile
  \global\output{\normaloutput\page\lheader\rheader}}
\setpage
\vbox to \vsize{} % the first \topmark won't be null

\def\con{%
  \write\cont{} % ensure that the contents file isn't empty
  \closeout\cont % the contents information has been fully gathered
  \par\vfill\eject % finish the preceding page
   \rightskip 0pt \hyphenpenalty 50 \tolerance 200
  \setpage
  \output{\normaloutput\page\lheader\rheader}
  \titletrue % prepare to output the table of contents
  \pageno=\contentspagenumber \def\rhead{TABLE OF CONTENTS}
  \message{Table of contents:}
  \topofcontents
  \line{\hfil Section\hbox to3em{\hss Page}}
  \def\Z##1##2##3{\line{\ignorespaces##1
    \leaders\hbox to .5em{.\hfil}\hfil\ ##2\hbox to3em{\hss##3}}}
  \readcontents\relax % read the contents info
  \botofcontents \end} % print the contents page(s) and terminate
\let\contentspage=\con
\catcode`\@=\atcode
\catcode`\_=\uscode

\endinput