\def\immediate{\hbox{$\pm d_7 \ldots d_2$}}
\def\uimmediate{\hbox   {$d_7 \ldots d_2$}}
\newcommand{\jam}[8]{\hbox to .9in{$#1$ $#2$ $#3$ $#4$ $#5$ $#6$ $#7$ $#8$}}
\newcommand{\jamIM}[2]{\hbox to .9in{$\immediate$ $#1$ $#2$}}

\begin{quote}
\begin{tabular}{|l|c|l|l|}\hline
{\em Encoding} & {\em Fmt} & {\em Assembly} & {\em Meaning} \\ \hline \hline
\jam???zyx10& R & (add $x\ y\ z$) & $ Rx \gets Ry + Rz $ \\ \hline
\jam???zyx20& R & (sub $x\ y\ z$) & $ Rx \gets Ry - Rz $ \\ \hline
\jam???zyx30& R & (mul $x\ y\ z$) & $ Rx \gets Ry \times Rz $ \\ \hline
\jam???zyx40& R & (div $x\ y\ z$) & $ Rx \gets Ry \div Rz $ \\ \hline
\jam???zyx50& R & (mod $x\ y\ z$) & $ Rx \gets Ry \bmod Rz $ \\ \hline
\end{tabular}
\end{quote}
