% 16 by 25 dots 1cm apart
\documentclass{article}
\usepackage[a4paper, portrait, hmargin=2cm, vmargin=2cm]{geometry}
\usepackage{tikz}
\thispagestyle{empty}

\begin{document}
\begin{tikzpicture}
  \foreach \x in {0,...,16} {
    \foreach \y in {0,...,25} {
      \filldraw[black] (\x,\y) circle (.5pt);
    }
  }
\end{tikzpicture}
\end{document}