Apple’s PowerPC Era (1990s–2000s)

RISC adoption and PowerPC era

Apple adopted the PowerPC (PPC) architecture in the mid-1990s as a shift away from Motorola’s 68K CPUs. In 1991, Apple formed the AIM alliance with IBM and Motorola to develop a modern RISC processor for Macs. The first Power Macintosh models launched in 1994, introducing the PPC 601 chip and using a built-in 68K emulator in System 7 to run legacy Macintosh apps. Over the next decade, Apple’s desktop and laptop lineup ran on PPC processors (branded as G3, G4, G5 in products like iMacs, PowerBooks, and Xserves), until Apple announced a switch to Intel in 2005 and phased out PPC-based Macs by 2006.

Architecture strengths and transition to Intel

#PowerPC was a 32/64-bit RISC architecture featuring a load–store design and superscalar execution, which delivered significant performance gains over Apple’s previous CISC chips. In the mid-1990s, PPC CPUs often matched or exceeded the fastest x86 processors in benchmarks. Apple and its partners added enhancements like the 128-bit AltiVec vector engine for multimedia acceleration in the G4 generation. However, by the early 2000s the PPC roadmap hit a wall: IBM and Motorola/Freescale struggled to increase clock speeds and reduce power consumption. The flagship PowerPC G5 (Apple’s first 64-bit CPU in 2003) ran hot and could not be adapted for laptops, and IBM failed to meet Apple’s 3 GHz speed target. Citing these performance-per-watt limitations (heat and energy usage), Apple announced in 2005 that it would abandon PPC in favor of Intel’s CPUs, ending the PPC era to pursue faster, cooler chips.

Legacy in macOS and Rosetta compatibility

Apple’s PPC era left a lasting legacy on macOS’s architecture and development practices. The OS and development tools were made multi-architecture – originally to support fat binaries that contained both 68K and PPC code during the 1990s transition, and later “Universal” binaries for PPC/Intel during the 2006 transition. Apple introduced the Rosetta dynamic binary translator in 2006 as part of Mac OS X 10.4, allowing PPC-only Mac applications to run transparently on Intel-based Macs. Although support for Rosetta (and PPC apps) was eventually dropped in Mac OS X 10.7, the concept was revived as Rosetta 2 in 2020 for the Intel-to-ARM switch in Apple’s silicon. These measures (e.g., fat binaries, cross-compiled frameworks, and binary translation) reflect a design philosophy born in the PowerPC era that still informs macOS’s platform agility and developer tooling.

Reading

  1. Apple’s 2005 WWDC Keynote: Intel Transition Announcement
  2. Mac OS X Internals: A Systems Approach
  3. Rosetta and Universal Binary documentation from Apple Developer