Mac OS 8.5, Mac OS 9: Performing a Clean Installation

This technical document describes the clean installation procedure for Mac OS versions 8.5 to 8.6 and 9.0 to 9.2.2.
This article has been archived and is no longer updated by Apple.
Performing a clean installation creates a new System folder on your hard disk. The old System folder is renamed Previous System Folder. You may want to perform a clean installation if you are having persistent difficulties with your computer that a normal reinstallation does not solve.

Important: Because your computer has a new System Folder, after a clean installation you must reinstall third-party fonts, extensions, and control panels that you have added to your system or that came with programs you have installed.

The steps below assume that you are accepting the default choices for installing system software. You may customize what gets installed by manually selecting the various system software components after clicking Customize.

To perform a clean installation:

  1. Start up your computer from the system software CD. You should use a version of system software that came with your computer, or later.

  2. Open the Mac OS Installer application.

  3. In the Welcome dialog box, click Continue.

  4. In the Select Destination dialog box, click Options.

  5. Select the Perform Clean Installation option, then click OK.

  6. Select the destination hard disk, then click Select.

  7. Click Start to begin installation.

After you're sure you've copied all the items you want to save into your new System Folder, delete the Previous System Folder from your hard disk.

Related documents

26055 Mac OS 8.0 & 8.1: Clean Installation Instructions
25517 Mac OS: Versions, builds included with computers (since 1998)

Published Date: Feb 18, 2012