The Cray C90 series (initially named the Y-MP C90) was a vector processor supercomputer launched by Cray Research in 1991. The C90 was a development of the Cray Y-MP architecture. Compared to the Y-MP, the C90 processor had a dual vector pipeline and a faster 4.1 ns clock cycle (244 MHz), which together gave three times the performance of the Y-MP processor. The maximum number of processors in a system was also doubled from eight to 16. The C90 series used the same Model E IOS (Input/Output Subsystem) and UNICOS operating system as the earlier Y-MP Model E.