PCSX2 is a PlayStation 2 (PS2) emulator for the Microsoft Winows and Linux operating systems. With the most recent versions, many PS2 games are playable (although speed limitations have made play-to-completion tests for many games impractical), and several games are claimed to have full functionality. The main bottleneck in PS2 emulation is emulating the multi-core PS2 on PC architecture. Although each CPU can be emulated perfectly, getting the synchronization and timing between them to be accurate is very difficult (Sony itself has found it difficult in perfecting a software emulator of the PS2 on the PlayStation 3).