CPU
A number of programs which provide compatibility for running programs designed for other operating systems on the same hardware are sometimes mistaken for emulators:
- WINE runs Microsoft Windows programs on various Unix-like operating systems running on x86 machines
- LINE runs x86 Linux programs on Microsoft Windows
- iBCS (Intel Binary Compatibility Standard) allows a number of x86 Unix operating systems to run a common binary format
- FreeBSD and other BSD Unixes have system call translation allowing them to run Linux binaries compiled for the same platform
- SCO UNIX has a similar "Linux kernel personality"
- VMware, Virtual PC, ShapeShifter, and Mac-On-Linux run entire operating systems inside another. This is called virtualization. Basilisk II also supports virtualization on m68k platforms.