\begin{tikzpicture}[
	scale=1.0,
	fine/.style={circle,draw=black,thick,inner sep=2},
]

\draw[step=1.0,black] (0.75,0.75) grid (6.25,6.25);
\draw[step=0.5,gray,thin,xshift=1.75cm,yshift=1.75cm] (0,0) grid (3.5,3.5);

\foreach \x in {0,...,7}
	\foreach \y in {0,...,7}
		\node[fine] at (1.75+0.5*\x,1.75+0.5*\y){ };
\end{tikzpicture}