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  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.