iMac G3 not seeing RAM

[ScreenSavers]

Hi everyone. I have a Blueberry “5 flavors” tray loading iMac that I upgraded with two brand new 256mb memory modules for a total of 512mb. Only problem is it’s registering them as 128mb modules for a total of 256mb. This is with macOS 9.2.2. I want to install OS X 10.3 on it but it panics on boot from the CD (may not even be a related issue). It runs solidly on OS 9 but it won’t read the memory correctly. What am I doing wrong?

Thanks!
Luke.

 

[Dronecatcher]

I'm guessing you've bought high density RAM which the iMac can only read half of - I had the same issue with my Powermac G3.

 

[ScreenSavers]

That sounds very likely. I can’t seem to find low density laptop sized PC 100 in 256 MB though.

 

[Raging Dufus]

Ok, two things:

1. Although everymac.com says your iMac will take 512MB, lowendmac.com says maybe, maybe not:
   • "The exact amount a Rev. A-D iMac can be upgraded varies from unit to unit. We have field reports of some models accepting 256 MB modules in both memory socket and reaching 512 MB – and other reports of early iMacs that won’t work at all with 256 MB modules. There appears to be no way to know in advance whether a particular iMac will work with a certain sized memory module."
2. I can't tell from the screenshot you provided, but it's likely your iMac needs a firmware update. Let's put it this way: if the machine has only ever run Mac OS 8 or 9, it definitely needs a firmware update. Every Mac from that vintage would have required new firmware in order to boot OS X. That should solve your Panther booting problem, and maybe your RAM problem too (although I think Dronecatcher's probably right about the RAM density).

Now here's the bad news: you're really gonna have to dig to find that firmware update. It's mentioned on this old Apple support page, but the link to download goes nowhere because of Apple's butchering of their support pages long ago. I tried finding it through the Wayback Machine, too - same story. It's out there somewhere, so search hard and you'll find it.

 

[B S Magnet]

Now here's the bad news: you're really gonna have to dig to find that firmware update. It's mentioned on this old Apple support page, but the link to download goes nowhere because of Apple's butchering of their support pages long ago. I tried finding it through the Wayback Machine, too - same story. It's out there somewhere, so search hard and you'll find it.

Found it. Select the MacBinary, not the BinHex.

And more generally…

 

[ScreenSavers]

I’ll try that. I think I remember a few months ago looking for that firmware update and the iMac saying it was not needed. But I will check again soon. Thanks!

 

[Raging Dufus]

Found it. Select the MacBinary, not the BinHex.

And more generally…

Nice job! That second one is a sweet cache of obscure necessities. Very handy.

 

[Project Alice]

I wasn't aware of tray loaders having issues with 256MB sticks until I saw this thread and that link to LEM.
I have a Rev B bondi iMac, that has a Rev D 333Mhz CPU card installed in it. The original card had a corrupt rom. Mine is older than OPs as LEM suggests the earlier models most likely have more problems recognizing ram; mine doesn't.
I installed 512MB of ram in it and it has had no problem using it, both in OS 9 and OS X. I didn't know there was ever a firmware update for these either. I assume mine is already on the latest one being as it hasn't had ram issues and it boots tiger. I can't find any firmware version in OS 9's system profiler and the bootrom under OS X says 1.3f2.

My money would be on the high density ram if your firmware doesn't have an update.