Released under the terms of the GNU General Public License, Basilisk II is freeware, and its source code is available on GitHub, along with that of SheepShaver. Ports of Basilisk II exist for multiple computing platforms, including AmigaOS 4, BeOS, Linux, Mac OS X, MorphOS, Windows NT, and mobile devices such as the PlayStation Portable. SheepShaver is an alternative that emulates PowerPC-based systems that run classic Mac OS. Newer versions are incompatible because they require a PowerPC-based processor, which Basilisk II does not emulate. The latest version of classic Mac OS that can be run within Basilisk II is Mac OS 8.1, the last 680x0-compatible version. Alpha versions became available in January 1999 with the first non-alpha release in October of the same year. My experience with SheepShaver is limited. Mac OS 8.1 was the last OS to support 68k processors and only ran on 68LC040s and and 68040s.
Basilisk II is the successor to 'ShapeShifter', an earlier Mac emulator for Amiga OS. Basilisk only lets you use up to System 7.5.5 (not sure about System 7.6) if you're using a Mac IIci ROM and up to Mac OS 8.1 when using a Quadra 900 ROM.
