ARCHIVED: In Mac OS 9.x and earlier, what is a clean system install, and how can I do it?

Note: Although Mac OS X 10.2 and later has a similar feature called Archive and Install, this document applies only to Mac OS 9.x and earlier.

A clean install replaces the System Folder, which contains all the vital parts of the Mac OS, instead of updating or modifying it. Typically, the old System Folder is renamed Previous System Folder. A clean system install is usually only necessary if parts of the system have become corrupt or damaged and cannot be repaired by utility programs such as Disk First Aid or Norton Utilities.

Note: In the following instructions, you will be directed to boot your computer from your system installation disks. These are the media, either floppy disks or a CD-ROM, that have the installation software for your operating system. If you have floppy disks, insert the first system installation disk in your floppy disk drive, then restart your computer. If you have a CD-ROM, put it in your CD-ROM drive, restart your computer, and immediately press the c key. The computer will use the floppy or CD as its startup disk, and you should be able to begin your clean install. For more information about booting from other media, see ARCHIVED: On a Mac, how do I change my startup volume or boot from an alternative volume, disc, or device?

Clean install for Mac OS 7.6 and later

1. Insert the first system installation disk or the system installation CD in the appropriate drive, then restart your computer. (Mac OS 8.5 and higher are available only on CD-ROM.)
2. Start up the installer, then click Options....
3. Check the box for Perform clean installation. In Mac OS 7.6, check Create new System Folder (clean installation...). Run any needed updates.

List of the updates:

• Mac OS 7.6 updates to 7.6.1
• Mac OS 8.0 updates to 8.1
• Mac OS 8.5 updates to 8.6
• Mac OS 9.0 updates to 9.1
• Mac OS 9.1 and 9.2 update to 9.2.1 (This update is only available for computers that can run Mac OS X.)

Clean install for Mac OS 7.5.x

1. Insert the first system installation disk or the system installation CD in the appropriate drive, then restart your computer.
2. Launch the system software installer, then press Cmd-Shift-k.
3. Select the option to do a clean system installation.
4. Install the software and run any needed updates.

List of the updates:

• Mac OS 7.5 updates to 7.5.3 (with Update 2.0)
• Mac OS 7.5.3 updates to 7.5.5
• For Macintosh computers with PowerPC processors running Mac OS 7.5.5, install the PowerPC interrupt extension

Clean install for Mac OS prior to 7.5

1. Rename the System Folder to Previous System Folder. For more information, see ARCHIVED: In Mac OS X, how do I rename a file, folder, or volume?
2. Drop the System suitcase file into the Preferences folder.
3. Insert the first system installation disk or the system installation CD-ROM in the appropriate drive, then restart your computer.
4. Click the installer and install your system. Run any updates to the system.

Note: After a clean installation, you will need to move any third-party or non-standard software you have installed from your Previous System Folder to your new System Folder. This includes any fonts, control panels, extensions, and other system software that is not a part of a standard Mac OS installation. Place this software in the appropriate folders inside the System Folder (e.g., fonts should be in the Fonts folder, control panels in the Control Panels folder). Make sure that third-party software is compatible with any updates you may have installed. Alternatively, you may wish to reinstall third-party software from the original installation disks as a way to insure that your system is free of corruption.