How to Format an Apple iMac G3

Written by christopher capelle
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Apple's iMac G3 was a marvel in both design and functionality when introduced in 1998. But now that users are replacing these iMacs with newer Mac models, they need to securely remove their data from their old Macs. Formatting the hard drive, which destroys all of the data on it, is the best way to expunge all your personal information from your iMac. It is a fairly quick and simple process, but copying your data onto another computer or hard drive can be time consuming.

Skill level:
Moderately Easy

Things you need

  • Mac OS installation disc (OS X.4 or earlier)
  • FireWire cable

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  1. 1

    Confirm that any data you want to save has been copied from the G3 and archived. Once the internal hard drive has been reformatted, the chances of recovering any of your files is virtually zero.

  2. 2

    Copy your files using whatever means are most convenient for you. This could be an attached external hard drive, a flash drive or via network connection. Using an external CD or DVD burner is also a possibility, but this is a slow, laborious process on a G3, so avoid it if you can.

  3. 3

    Locate the original OS installation disc if possible. If you are unable to find the original disc, a standard Mac OS install disc will work. However, installing any OS later than X.4 (Tiger) is not recommended on G3 iMacs.

  4. 4

    Insert the OS installation disc into the CD/DVD drive and reboot while holding down the "C" key. When the computer boots up, click on the right-pointing arrow. When you see the menus at the top of the screen, select "Utilities."

  5. 5

    Choose Disk Utility from the options under Utilities. Highlight the internal hard drive in the list on the left, and then click on the "Erase" tab. Once the drive is selected, click on the "Erase..." button in the lower right of the pane.

  6. 6

    Select "Erase" in the next window. This is a warning that all of the data on the drive will be destroyed. Once the process has finished, quit Disk Utility and continue to follow the wizard to install a clean copy of the OS. Reboot when prompted.

  7. 7

    Turn off the iMac when the first start-up screen appears if you're planning on selling it or giving it away. This allows the next user to enter his user name and registration information. But if you plan on keeping it, continue the set-up process by following the installation wizard.

  8. 8

    Boot up the iMac holding down the "T" key if you can't find an OS installation disc. This starts it in FireWire mode, which allows you to connect it to another Mac using a FireWire cable, and you'll be able to see the iMac's hard drive mounted on the desktop on the second Mac. Launch Disk Utility and erase the drive as described in Steps 5 and 6. This will format the hard drive, but you won't have a usable computer until you install an operating system on it.

Tips and warnings

  • Always keep the original media on hand for situations like this.
  • Likewise, always keep the original packaging in case you sell the Mac and need to ship it.
  • It bears repeating--once you've formatted the drive, your data is gone. Double check before proceeding to confirm it's been properly copied.
  • Early G3 iMac models don't have FireWire capabilities, so if that's what you have, you will have to locate an installation CD if you want to properly format it.

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