The hardware platform of Mac OS X

Sometimes ago, the standard hardware platform of Mac OS X supported was the full line of Mac computers, such as the laptop, desktop, or server. But later, the hardware platform do not continued to support some of the older hardware anymore. For example, Panther does not support "beige" G3s, and Tiger does not support systems that pre-date Apple's introduction of integrated FireWire ports. Mac OS X v10.5 "Leopard” has dropped support for all PowerPC G3 processors and for PowerPC G4 processors with clock rates below 867 MHz. Mac OS X v10.6 "Snow Leopard" supports Macs with Intel processors, not PowerPC.

Tools applied to the installation disc have been developed by third parties. The tool enables installation of newer versions of Mac OS X on system not officially supported by Apple. This includes a number of pre-G3 Power Macintosh systems that can be made to run up to and including Mac OS X 10.2 Jaguar, all G3-based Macs which can run up to and including Tiger, and sub-867 MHz G4 Macs can run Leopard by removing the restriction from the installation DVD or entering a command in the Mac's Open Firmware interface to tell the Leopard Installer that it has a clock rate of 867 MHz or greater. Except for features requiring specific hardware, the operating system offers the same functionality on all supported hardware.

The new Mac OS X retain some compatibility of older Mac OS applications by providing an emulation environment, which allows users to run Mac OS 9 as a process within Mac OS X, so that older applications can run on Mac OS X as it running under the older operating system. Classic is not supported on Mac OS X v10.5 "Leopard", but users still requiring Classic applications on Intel Macs can use the SheepShaver emulator to run Mac OS 9 on top of Leopard.