Since the last TOP500 [3] report the list has changed on quite some points. In this section we indicate the systems that have dropped out and we describe the architectures that have come in newly. The new list is given in Table 1.1
Table 1.1: 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. The system that
appear for the first time in the table are marked with a *.
The following systems have dropped from the list:
For the description of the various types of architectures one is
referred to [3] or [2]. In this section we only
describe the machines that appear for the first time in Table 1.1
in alphabetical order. For the descriptions of the other systems are
given in [3]. 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.