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G3 M4984 boot options not working


Feb 3, 2022
I grabbed a G3 iMac M4984 that posts but goes to a ?/Finder icon, I assumed the HD was shot. Taking it apart the battery is the original and has leaked just on its end but the board seems clean. I replaced it with a 3.6v, put in a HD, and put it back together. It does not boot to the CD of 9.2.1.universal that works on my G3 laptop by holding C. I do not have a Mac usb keyboard and have tried holding T, C, P/R/Win/ALT with nothing helpful happening. The Win/ALT/P/R causes the machine to go Amber/Green and make the start up chime, I did that for 3 chimes and let the keys go which led to the same ?/Finder icon.

Few things to note
  • The CD is good, I booted and reinstalled OS9 on my G3 laptop.
  • The CD rom spins and sounds ok but I assume it is bad.
  • I have the G3 laptop and a firewire cable to try target disk mode but the iMac wont take T or C at post
  • The IDE HD I put in was formatted on a newer 2013 macbook, my G3 would not see it over the usb adapter I have.
Just looking for some guidance on next steps to get this thing running, I'm a bit out of my depth with Macs so please excuse my ignorance if I missed something obvious.
Do you have an older OS 8 disc you can try? 9.2 is really late for those macs and I've never trusted those universal discs to boot reliably.
I can likely grab and burn an ISO of one. The 9.2.1 works on my G3 laptop so I thought it might boot the iMac.
I'm grabbing 8.5 now and will try that in a few.

Should T work on the iMac? It works on the G3 Macbook to get into target disk mode but the iMac does nothing .
I think I'm going to have to get a USB Mac keyboard to rule out incompatibility. I was able to get the pram clearing cycle to happen with this keyboard but maybe C and/or T at post is not working?
Mac OS 9.2.x was really only meant for later G4 Macs and Classic Mode in OSX. There are ways to get it running on an iMac, but I wouldn't recommend it because it will be very slow. The tray loading iMac has basically the slowest G3 CPU and the 512 MB RAM limit and crappy ATI Rage video chip don't help it.

The oldest OS that that machine can run is I believe 8.1, but I would recommend 8.6.1. It offers the best balance between features and speed, you can run most OS 9 software on it.

There are a bunch of arbitrary limits on partition sizes on that machine, but I don't know if they apply to Classic Mac OS or just OSX. I think the largest bootable primary partition size is 8 GB.
Ah, thank you. I grabbed 8.5 and no dice (the disc worked on the iBook).
It could be partially the IDE drive in there but I'd assume it would boot to a CD or target disk but neither seem to work (the CD sounds like it is reading). Sadly I do not have a PATA laptop cd drive to swap in.
Getting 8.1 now but I think this machine is 1. shot for lack of a technical term and 2. not worth the further effort. If 8.1 does not boot I am going to cut my losses and put it up on FB for basically nothing to avoid it going to the recycler.

Edit- I had a moment I had to share... Grabbed the firewire cable to mess with target disk mode only to realize that the iMac has no firewire port 😅
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You have one of the earliest iMac G3 models then, the later slot loading models I know had firewire because I had one years ago. I think some of the final tray loading models had firewire also.

Try some other OS install media, like 8.1 or 8.6. 8.5 was notoriously buggy. If none of those work, I'd suspect the optical drive is dead.

Another (painful) workaround is to remove the IDE drive from the machine, put it on a USB to IDE adapter and format it on another Mac and install the system software to it. Just make sure that when you format the drive that you make the boot partition under 8 GB.

While you're in the machine, you can check for bulging/leaking capacitors, those early iMacs were notorious for capacitor plague.
Neither of the slower 350 MHz slot loaders and none of the tray loaders had Firewire ports; you needed an iMac DV for that until the early (and faster) 2001 models came out.

Hold down 'C' to boot to CD (if it's bootable) or alternatively hold down ALT to get a list of what the Mac thinks is bootable.

As far as a version, 8.6 is the best bet. You may be able to get away with early OS 9 (like 9.0.4 or similar) if it has enough RAM. There are a few iMac-specific software restore images out there, one of those might work too, although you have to be careful with those as the revision A (and maybe B) shipped with OS 8.1 which will not run on the later fruit-coloured revision C and D.