The IBM mainframe line that superseded System/370. Introduced in 1990, the 32-bit System/390 was an evolution of the Enterprise System Architecture introduced with the System/370. The bipolar-based ES/9000 models, which came both water cooled and air cooled, incorporated fiber-optic channels, clustering (see Parallel Sysplex) and other advancements. From Bipolar to CMOS In 1994, IBM introduced the next generation System/390s known as Parallel Enterprise Servers and abbreviated the name to S/390. These machines contained single-chip CMOS CPUs that used less power and dissipated less heat than the bipolar-based ES/9000s. In 1995, IBM introduced models with up to 10 CPUs, and as many as 32 10-way systems could be combined to make a multiprocessing system with 320 CPUs. As requirements increased, customers migrated from ES/9000s to clusters of the CMOS-based S/390s. See System/360, System/370 and IBM mainframes.