\begin{table}[hpbt]
\begin{center}
\begin{tabular}{|c|c|c|c|c|c|c|c|}\hline
Device       &Type No. &$c_i$ &$t_i$ &$d_i$ &$l_i$  &$u_i$  &CLB cost\\ 
\hfill       &(i)      &(CLB) &(IOB) &(N\$) &\hfill &\hfill &$d_i / c_i$\\
\hline
\hline 
XC3020xx-xx  &1        &64    &64    &1.00  &0.8    &0.9    &0.0156\\
\hline
XC3030xx-xx  &2        &100   &80    &1.36  &0.8    &0.9    &0.0136\\
\hline
XC3042xx-xx  &3        &144   &96    &1.84  &0.8    &0.9    &0.0128\\
\hline
XC3064xx-xx  &4        &224   &110   &3.15  &0.8    &0.9    &0.0141\\
\hline
XC3090xx-xx  &5        &320   &144   &4.83  &0.8    &0.9    &0.0151\\
\hline 
\end{tabular}
\caption{A subset of the Xilinx XC3000 device library}
\label{tb:tb1}
\end{center}
\end{table}

