%%
%% The LaTeX Companion, 2ed (second printing August 2004)
%%
%% Example 3-4-8 on page 156.
%%
%% Copyright (C) 2004 Frank Mittelbach, Michel Goossens,
%%    Johannes Braams, David Carlisle, and Chris Rowley
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3
%% of this license or (at your option) any later version.
%%
%% See http://www.latex-project.org/lppl.txt for details.
%%

\documentclass{ttctexa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{207.0pt}

\StartShownPreambleCommands
\usepackage{fancyvrb}
\usepackage[OT1,T1]{fontenc}
\StopShownPreambleCommands
\begin{document}
\fontencoding{OT1}\selectfont
\begin{Verbatim}[fontfamily=tt]
Family `tt' is fine in OT1: \sum_{i=1}^n
\end{Verbatim}
\begin{Verbatim}[fontfamily=helvetica]
But `helvetica' fails in OT1: \sum_{i=1}^n
\end{Verbatim}
\fontencoding{T1}\selectfont
\begin{Verbatim}[fontfamily=helvetica]
...  while it works in T1: \sum_{i=1}^n
\end{Verbatim}
\end{document}