Another key feature of Copland is that it is fully PowerPC (PPC) native. System 7 had been ported to the PowerPC with great success; large parts of the system run as PPC code, including both high-level functions, such as most of the user interface "toolbox" managers, and low-level functions, such as interrupt management. There is enough 68k code left in the system to be run in emulation, and especially user applications, however that the operating system must map some data between the two environments. In particular, every call into the Mac OS requires a mapping between the interrupt systems of the 68k and PPC. Removing these mappings would greatly improve general system performance. At WWDC 1996, engineers claimed that system calls would execute as much as 50% faster.