(
RISC
System
64) A family of RISC-based 64-bit CPUs from IBM based on the PowerPC chip family. Architected for commercial workloads rather than computation-intensive applications, the RS64 chips were used in various models of AS/400 (iSeries) and RS/6000 (pSeries) systems starting in 1997. They were superseded by the POWER4 CPUs, introduced in 2001. Over the years, clock speeds ranged from 125 to 750 MHz, and RS64 CPUs were code-named Northstar, Pulsar, IStar and SStar. See
POWER and
PowerPC.