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You can use the Gestalt Manager to determine if the Name Registry exists in the user's version of Mac OS, using the gestalt selector 'nreg'. Check the routine's error return first; Gestalt will return gestaltUndefSelectorErr if the Name Registry is not present. If the routine was successful, check the gestalt return for the Name Registry version number (currently 0). The Gestalt Manager is discussed in Inside Macintosh: Operating System Utilities. Its use in the second generation of Power Macintosh computers is described in Macintosh System Gestalt.
If the Name Registry is not present, the computer does not support PCI cards. The converse is not true. For example, the iMac computer does not have a PCI bus for expansion cards, but it does utilize and support the Name Registry.