The IBM RS64 is a family of microprocessors that were used in the late 1990s in IBM's RS/6000 and AS/400 servers.

These microprocessors implement the "Amazon", or "PowerPC-AS", instruction set architecture (ISA). Amazon is a subset of the PowerPC instruction set, with the addition of special features not in the PowerPC specification, mainly derived from POWER2 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 IBM 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.

In 1995 IBM released the Cobra, or A10 processor, the first implementation of PowerPC AS, for AS/400 systems. It was a single-chip processor running at 50-77 MHz. It was designed with a semi-custom methodology, as a consequence of time-to-market constraints. The die contains 4.7 million transistors and measures 14.6 mm by 14.6 mm (213 mm²). It was fabricated by IBM in their CMOS 5L process, a 0.5 µm, four-layer-metal CMOS process. It used a 3.0 V power supply and dissipated 17.7 W maximum, 13.4 W minimum at 77 MHz. It was packaged in a 625-contact ceramic ball grid array (CBGA) that measured 32 mm by 32 mm.