\begin{twocollist}\itemsep=0pt
\twocolitem{\_\_ALPHA\_\_}{DEC Alpha architecture}
\twocolitem{\_\_INTEL\_\_}{Intel i386 or compatible}
+\twocolitem{\_\_IA64\_\_}{Intel 64 bit architecture}
\twocolitem{\_\_POWERPC\_\_}{Motorola Power PC}
\end{twocollist}