Microsoft Virtual PC (renamed Windows Virtual PC for the Windows 7 release) is a virtualization program for Microsoft Windows operating systems, and an emulation program for Mac OS X on PowerPC-based systems. The software was originally written by Connectix, and was subsequently acquired by Microsoft. In July 2006 Microsoft released the Windows-hosted version as a free product. In August 2006 Microsoft announced the Macintosh-hosted version would not be ported to Intel-based Macintosh computers, effectively discontinuing the product as PowerPC-based Macintosh computers are no longer manufactured. The newest release, Windows Virtual PC is available only for Windows 7 hosts.