The 32-bit versions of all the frameworks and libraries are of course still available, but running apps in both modes requires both stacks to be loaded, which is inefficient, and a big reason why Apple is strongly encouraging developers to get on the boat and build their apps with a 64-bit version.īecause the kernel in 10.5 is still 32-bit, the greater amount of addressable memory is achieved with some trickery. Snow Leopard will add a 64-bit kernel and many 64-bit user applications shipped by Apple.Leopard added 64-bit support throughout the system frameworks, so any app can be 64-bit.Tiger added 64-bit support for low-level system libraries, enabling 64-bit for non-GUI applications.The short answer is that Leopard is a mix of 32-bit and 64-bit.
