Emulator

An emulator is hardware or software that allows one computer system (called the host) to behave like another computer system (called the guest). Apple Computer (now Apple Inc.) has relied on emulators through many hardware and software transitions throughout its history.

Software

 * Mac 68k emulator, used during the 68k to PowerPC processor transition.
 * Classic environment, used during the classic Mac OS to Mac OS X transition.
 * Rosetta, used during the PowerPC to Intel processor transition

Hardware

 * Apple IIe Card
 * DOS Compatibility Card
 * PC Compatibility Card

3rd-party emulators

 * Advanced Macintosh Substitute
 * Basilisk II
 * Connectix Virtual Game Station
 * Mini vMac
 * PearPC
 * QEMU
 * Speed Doubler