Be Inc.
SheepShaver was originally commercial software when first released in 1998, but after the demise of Be Inc., the maker of BeOS, it became open source in 2002. It can be run on both PowerPC and x86 systems; however, it runs more slowly on an x86 system than on a PowerPC system, because of the translation between the PowerPC and Intel x86 instruction sets. SheepShaver has also been ported to Microsoft Windows.