Tera/Cray used to make the MTA (multi-threaded architecture) that had 128 register sets so it could run 128 threads in a round-robin fashion. The purpose was to

Tera/Cray used to make the MTA (multi-threaded architecture) that had 128 register sets so it could run 128 threads in a round-robin fashion. The purpose was to cover the latency of main-memory access.