Firmware issue updating from 10.2.8 to 10.4

Question

I'm trying to update an old 400Mhz iMac from 10.2.8 to 10.4 but I can't even get started cause it says I need to update the firmware. But when I run the software updater it says I'm all up to date. What do I need to do?

Answer 1

I believe that you are in good shape when it comes to the firmware. My understanding is that you have to have the latest firmware to run Mac OS 10.2. I keep a file about upgrading to tiger and I've attached it.
OK here are some more comparison charts:
http://lowendmac.com/macdan/05/0202.html
http://docs.info.apple.com/article.html?artnum=58669
Bringing G3 iMacs and Other G3 Macs into the Tiger Age
http://lowendmac.com/macdan/md07/1207.html
There are some CD versions of tiger.
http://www.godzillagamer.net/servlet/the-276/Mac-OS-X-10.4/Detail
Caveat Emptor!
You could buy an external DVD drive. It needs to be firewire and bootable by Mac OS. If you have another PPC with firewire, you could try target Disk mode and installed tiger that way.
"If you call Apple Phone Sales 1-800-692-7753, you can order Tiger 10.4.x, for $129.00."
ali brown
AppleCare Support Phone Number: 1-800-275-2273
open 6am to 6pm Pacific Time
You need to figure out the level of your firmware before installing 10.2 or greater. ( The PC name for firmware is BIOS. ) Installing 10.2 with a down level firmware will most likely make your iMac unusable and difficult to fix.
Figuring out what level of firmware you have?
1) Mac OS 9.x or 8.x, you need to use the Apple System Profiler.
Apple -> Apple System Profiler
2) Mac OS X, use the System Profiler.
Apple -> About This Mac
click on the More Info... tab
click on Hardware
read the Boot ROM Version
3) Open Firmware, boot into Open Firmware.
Power on your iMac while holding down commandoption+of
The first output line contains the firmware level. Mine reads:
Apple PowerMac4,1 4.1.9f1 BootRom built on 09/14/01 at 13.18.04
Copyright 1994-2001 Apple Computer Inc.
Some machine may not contain the firmware level but some other number which can be translated to the firmware level.
On my machine, I have 4.1.9f1.
What firmware do you need?
http://docs.info.apple.com/article.html?artnum=86117
For a slot loading iMac, this article indicates that you need to be running 9.1.
http://docs.info.apple.com/article.html?artnum=75130
"The iMac Firmware Update 4.1.9 will only run on iMac computers with lot-loading CD or DVD drives running Mac OS 9.1 or later from a local drive. If you are using Mac OS X you must boot from a local Mac OS 9.1 or later writeable partition (not a CD, or network disk) prior to following the update instructions."
You can download the updates from the Apple site.
http://support.apple.com/kb/HT1387?viewlocale=en_US
For tiger, you need 256meg of memory. For panther, you need 128 meg of memory.