In this section we list the architecture summaries of the following machines that appear in the TOP500 as shown in table 1:
Table 1: Machines are ordered by frequency of occurrence (N). 
is
the cumulative maximum observed performance, 
is the cumulative
theoretical peak performance for each system type. First, medium, and last
are the first, median, and last entries of the a system type in the TOP500
list ordered by performance.
We discuss each of the systems as they appear in table 1 in
alphabetical order. Apart from the systems parameter list that is given for
each system also the values of and as available from
[1] are quoted together with the number of nodes associated with these
values. The reason that the system parameter list is not sufficient is that the
maximal theoretical peak performance is given for the maximal configuration of
a system. Such a system may not actually exist. On the other hand, sometimes
systems of a certain type have been clustered to obtain a distributed system
with more processors than a maximal configuration of that can contain. Examples
are the Intel Paragon XP/S and the Hitachi S-3000 series.