@Cyberus
MultiTOS is a UNIX-like kernel (called MiNT) that runs TOS in a virtual machine. So you have two sides, the UNIX-like MiNT and the TOS-side for legacy apps.
There are TOS-replacements, allowing totally GPL'd MultiTOS workalike OS's out there, such as FreeMiNT and SpareMiNT, including a way to emulate such on foreign hardware.