Rosetta was a PowerPC CPU emulator that allowed running any kind of PowerPC OS X application on Intel Macs. Carbon was a set of largely OS 9 compatible APIs th

Rosetta was a PowerPC CPU emulator that allowed running any kind of PowerPC OS X application on Intel Macs. Carbon was a set of largely OS 9 compatible APIs that allowed an easy transition for apps that could be recompiled. Classic was a virtualized OS 9 environment available on OS X (up to 10.4 Tiger, PPC Mac only) that allowed running unmodified binaries for pre-OS X Macs. Most things that didn't require special hardware access or precise timing ran fine, but things like real-time audio and MIDI applications did not.