System 7.5.5: Clean Installation Procedure

This article contains the procedure for performing a clean installation of System 7.5.5.
This article has been archived and is no longer updated by Apple.
Step 1: Find out which version of system software you should install.

The earliest version of system software you should install on your Macintosh computer is System 7.5.5. Apple has tested this version for Year 2000 compliance on Macintosh computers back to and including the Macintosh Plus. It is available for free download from Apple's Web site. See step two for more information on how to get it.

System 7.5.5 requires at least 4 MB of memory and up to 21 MB of hard disk space. Make sure your computer meets these minimum requirements before proceeding.

Your Macintosh computer may be able to use a later version of system software if it came with a later version, or if you purchased an upgrade. For more information on performing a clean installation of versions later than 7.5.5, please see the links at the end of this article.

Step 2: Get the system software you need.

Find the system software CD or floppy disk set that came with your computer. If it includes System 7.5.3, you only need to get System 7.5.5 Update.


System 7.5.5 can be downloaded from the Apple Software Downloads Web site ( in a two-step process. First, you must download System 7.5.3, then System 7.5.5 Update.

Step 3: Start up the computer from the Disk Tools disk, or system software CD.

If your computer only has a floppy drive, start up the computer using a Disk Tools disk. If your computer has a CD-ROM drive, start up the computer using your system software CD.

Step 4: Run the Disk First Aid program to repair any errors.

After you have started up the computer from the Disk Tools disk or the system software CD, open the Disk First Aid program. Select the hard disk you want to check by clicking on its icon in the Disk First Aid window. Click the Verify button. Disk First Aid checks your disk for any errors. If Disk First Aid reports any errors, click the Repair button to repair them. Quit the Disk First Aid application.

Step 5: Update the hard drive driver software.

Find the appropriate hard drive utility for your computer on the Disk Tools disk or system software disc. Use Apple HD SC Setup with Macintosh computers that have a Motorola 680x0 family microprocessor and a SCSI hard drive. The following Macintosh computers have IDE hard drives and require that you use the Drive Setup application:
  • Macintosh LC 580
  • Macintosh LC 630
  • Macintosh LC 630 DOS
  • Macintosh Quadra 630 series
  • Macintosh Performa 580 series
  • Macintosh Performa 630 and 640 series
  • PowerBook 190 series

Apple HD SC Setup

Open the Apple HD SC Setup application. Click the Drive button until the name of your hard disk you want to update appears. Click the Update button, then the Quit button.

Drive Setup

Open the Drive Setup application. Click the name of the hard disk you want to update. Choose Update Driver from the Functions menu. Quit the application.

Step 6: Open the System 7.5.3 Installer application.

If you downloaded System 7.5.3 to your computer's hard disk, find and open the file called System 7.5.3 01of19.smi, then open the Installer application.

Step 7: Choose the Clean Installation option.

When the Installer application has opened, click Continue. Make sure Easy Install is selected from the pop-up menu. Press the Command, Shift and K keys on the keyboard. Select Install New System Folder and click OK.

Step 8: Click Clean Install to begin installation.

Click Clean Install to being the installation. When it has finished, restart the computer. Find and open the Installer application for System 7.5.5 Update. Click Install.

You have now finished installing a clean version of System 7.5.5 on your computer. The contents of your old System Folder are in a new folder named Previous System Folder.

You may need to install additional software such as fonts, printer or other device drivers, and application support files. You should reinstall these items from their original disks.

Related documents

8970: "System 7.1 through Mac OS 7.6: Compatibility With Macintosh Computers."
25114: "Mac OS 8, 9: Compatibility With Macintosh Computers."
30034: "Mac OS 7.6: Clean Installation"
26055: "Mac OS 8.0 and 8.1: Clean Installation Instructions"
58176: "Mac OS 8.5, Mac OS 9: Performing a Clean Installation "

Published Date: Feb 18, 2012