IBM RS64

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The IBM RS64 is a family of microprocessors introduced in the mid 1990s, and used in IBM's RS/6000 and AS/400 servers.

These microprocessors implement the "Amazon", or "PowerPC-AS", instruction set architecture (ISA). Amazon is a superset of the PowerPC instruction set, with the addition of special features not in the PowerPC specification, mainly derived from POWER2^{[citation needed]} and the original AS/400 processor, and has been 64-bit from the start. The processors in this family are optimized for commercial workloads (integer performance, large caches, branches) and do not feature the strong floating point performance of the processors in the POWER family, its sibling.

The RS64 family was phased out soon after the introduction of the POWER4, which was developed to unite the RS64 and POWER families.