| What do they do?
Extensions are optional extras which extend the capabilities of the core of the Mac OS, and consist of files stored in the Extensions folder inside your active System Folder. They include a wide variety of different files and functions: Open Transport’s components, for instance, are essential for communications and networking, while QuickTime provides support for movies and similar multimedia. Extensions are required to support printers, graphics cards, and most add-in and peripheral hardware devices. Many come as standard with the Mac OS, others come free with its installation options, and even more come with third-party software and hardware products. How do they work?
When your Mac starts up, it loads extensions after it has loaded control panels. Working in alphabetical order, each extension is checked to see if it needs to be loaded then, or can be left until an application calls for it. Some extensions actually ‘patch’ the Mac OS to alter its behaviour, and so affect all applications which try to use these patched features. Other extensions are only called when specifically required by applications which know about them. Because most require some memory, they usually increase the amount of RAM taken up by the Mac OS itself. What can go wrong with them?
Extensions are prone to conflicts with other extensions, control panels, applications, and anything else you have on your Mac. You can use Extensions Manager or a third-party substitute such as Conflict Catcher to turn them on and off to try to resolve conflicts and optimise use of memory. You can also alter the order in which they are loaded, although this approach has become less effective. How can I upgrade them?
Apple’s extensions are upgraded as part of a new release of the Mac OS, or with major components such as QuickTime, which may be made available separately. Third-party extensions, such as hardware drivers, are supported by their developers, although some are bundled with the Mac OS. Upgrading can, of course, bring new conflict problems, and should always be performed with caution. Further info
Web sites with further information include: the Mac Pruning pages, detailing all current Apple extensions, at mc04.equinox.net/informinit/MPP.html; and the Complete Conflict Compendium, listing most known extension conflicts, at www.mac-conflicts.com. | |
