Mac OS 9 upgrade from 8.6

No.

You must purchase retail either OS 9.1 or OS 9.2.1.

You can get a copy of the retail OS 9.2.1 Install CD direct from the Apple Store, but only by telephone.

Make sure you check out all of the following links as prices vary for the OS 9.x cds.

Ask the vendors the color of the CD lable. All universal full install CDs are white w/an orange/golden 9.x on it.

http://www.applerescue.com/index_link.htm
http://store.yahoo.com/hardcoremac/index.html (RECOMMENDED BY APPLE)
http://welovemacs.com/apsyso.html
http://macsolutions.com/
http://www.allmac.com/
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Do NOT buy a gray installation CD - those are not universal installers but model-specific [NO matter what the seller says about them!] OEM-versions have caused problems in the past when used on other computer models.

I do not trust eBay. However, there are many others who will & will recommend.

To run OS 9 effectively, you will also have to increase the RAM in that iMac. In other words you will have to buy two things, the OS itself as well as more RAM.

You can buy any version of OS 9, and upgrade from that version using free downloads. But as Baby Boomer points out, you must buy some retail version of OS 9. The sequence of upgrading, and the download links are here:
http://docs.info.apple.com/article.html?artnum=75288

Hello Deborah,

...And welcome !!

You've great advice from two of the Apple world's finest.

I usually recommend eBay since I'm a horse trader at heart, but in this case you're ahead of the game to go straight to an Apple vendor. There are at least ten times as many OS9 CDs you don'f want as the orange gold one you do want. You'd never think there would be so many grey labels, software restores, burned copies, bootable, non-bootable, and bootable if you hold your ears right copies that it makes your head spin - all "guaranteed to work" - and you wonder where there they all came from.

I just got an OS 9.1 to add to my collection, and it was actually cheaper from AppleRescue (than the auction I had been watching) and I didn't have to read the fine print, wait longingly by the mailbox, or chase the seller.

(If it had been half-price, I wouldn't have minded!).

But there are some items better purchased from traditional vendors, and the OS 9 CD is one of them.

Many happy regards.....Jon

Him Deborah -

To add one more item to the list of godd suggestions already presented -

Before deleting OS 8.6, make sure the firmware on your iMac has been updated. Most (if not all) versions of OS 9 will not install or even boot your model machine until that has been done. And, to install a firmware update the machine must be booted to the hard drive, and the firmware update run from the hard drive.

If you're not sure if the firmware is up to date, you can try installing it - if it is not needed, the installer will so state and refuse to run any further.

You can dowload the current firmware update for your model from either of these two Apple KBase articles -
Article #58174 - iMac: When to Install Available Updaters
Article #86117 - Firmware Updates