\font\Myfont=ptmb8r scaled 14000  % postscript font (times bold) in very large
                               % so the font will not be part of the ps file
                               % a normal TeXfont would be i.e. cmr12
\hsize=11.0in   % paperwidth
\vsize=6.5in    % paperheight (we use landscape)
\hoffset=-0.95in % normally [La]TeX has 1in margin all around
                % but for large signs we want to write all
                % the way to the border
\parindent=0pt  % no indentation for the first word of paragraphs

$\vcenter to \vsize{\vfil\centerline{\Myfont Welcome!}\vfil}$

\bye