  Supercomputer building is a many sceene, many authors game, comprising a lot
of different technologies, manufacturers and ideas. Checking data available in
the public database in a systematic way, some general tendencies and
limitations can be concluded, both for the past and the future. The feasibility
of building exa-scale computers as well as their limitations and utilization
are also discussed. The statistical considerations provide a strong support for
the conclusions.
