emulator

An emulator is software or hardware that allows a computer system to imitate another system. Emulation enables software or digital devices designed for one hardware or software platform to run on a different platform. It differs from virtualization in that emulation reproduces the original hardware’s behavior, including a different instruction set, timing, and peripherals, whereas virtualization typically runs guest software on hardware with a compatible instruction set through a hypervisor.

Emulation works by translating the guest system’s instructions and hardware interactions into actions on the host system. This can be done by interpretation, where each instruction is translated on the fly, or by dynamic recompilation, where blocks of guest code are translated into host code for faster execution. An emulator must model the guest’s central processor, memory layout, input/output devices, graphics, audio, and timing behavior. Accurate emulation aims to reproduce results and behavior as if the original hardware were present, while performance depends on host capabilities and the efficiency of the translation layer. Legal considerations may apply, as many emulation projects rely on firmware, BIOS images, or ROM dumps that are subject to copyright.

Uses and examples include software preservation, where emulation helps run legacy applications and games on modern hardware; cross-platform development and testing; and educational demonstrations of how different architectures operate. Notable emulators include MAME for arcade hardware, Dolphin for GameCube and Wii, PCSX2 for PlayStation 2, PPSSPP for PlayStation Portable, and QEMU, which supports multiple architectures and modes including virtualization. Emulation can offer features such as save states and graphical upscaling, but may also introduce compatibility gaps and input lag.