A microprocessor architecture developed in 1992 by Motorola and IBM, with some participation by Apple. A PowerPC microprocessor is RISC-based and superscalar, with a 64-bit data bus and 32-bit address bus. It also has separate data and instruction caches, although the size of each varies by implementation. All PowerPC microprocessors have multiple integer and floating-point units. The voltage and operating speed varies with the implementation. Starting with the PowerPC 740, the microprocessors were manufactured with copper, instead of aluminum, for better performance and reliability.