10 Replies Latest reply: Aug 16, 2008 6:35 PM by Kenichi Watanabe
MacShed Level 1 (0 points)
I have an old iMac G3 sitting in my room. I decided to boot it up today. It works surprisingly well. I even hooked up my ethernet and got an internet, albeit slow, connection. However, this little machine is running OS 8.5 and only has 32MB of memory. Any help/tips/suggestions that will help me to "update" the G3?

All the help is greatly appreciated!

iMac, Mac OS X (10.5.4), 24", 3.06 GHz Intel Core 2 Duo, 2 GB 800 MHz, 512MB NVIDIA GeForce 8800 GS
  • Allan Jones Level 7 (33,972 points)
    First we need to know if it has a tray-loading or slot-loading optical drive. There are significant differences in the upgrade path between the two basic iMac G3 models.

    If it has OS8.5, I suspect it's a tray-loader.

  • MacShed Level 1 (0 points)
    Yep, you got it. It's a tray loader all right.
  • Allan Jones Level 7 (33,972 points)
    Well, I'm more familiar with the "slot machines" but I think I can help.

    First, ask yourself how badly you want to upgrade this machine. Adding hardware like RAM and a larger hard drive (almost a necessity for running OSX) is one expense, but getting older versions of system software is getting pricey and difficult. It's easy to drop $200+ into a $25 computer and end up with a $35 computer.

    First, avail yourself of the excellent information on this Apple support page:


    Lots of useful links there.

    To install OSX 10.2.X or higher, you must update the firmware and, according to this article:


    you must have at least OS9.1 to use the updater. Another expense.

    The TL iMacs cannot support a Mac OX greater than 10.3.9 so don't run out and buy a copy of Tiger or Leopard.

    You need more RAM, even if you don't upgrade the OS. The Tray-loader takes notebook RAM and has two slots. However, only one is readily accessible; the second requires some disassembly and is should not be attempted if you're not comfortable inside a computer and have not observed the safety procedure for avoiding hi-voltage hazards inherent to all-in-one computers.

    RAM installation is detailed here:


    If the user-accessible slot is empty, the most RAM you can install without taking things apart is 288MB (a new 256MB stick in the top slot and leaving the factory 32MB stick in the bottom). Slim for OSX to me. Accesing the lower slot and putting another 256MB there would give you the machine's max RAM of 512MB. Not a bad number but it will cost you about US$70 or more.

    I believe info on upgrading the hard drive is on the same site. Poke around and you should find it. If you plan to run OSX, I consider a 40G hard drive to be the minimum. You should be able to install a drive up to 120G; this machine will not support anything larger.

    Again, the tray-loaders are not my long suite. I hope spudnutty or other with more TL experience can jump in.

  • Kenichi Watanabe Level 7 (33,184 points)
    Great info from Allan.

    Regarding the hard drive, the tray-loaders also have a limitation on the size of the startup disk. The startup disk must be within the first 8GB of disk space on the hard drive. During the startup sequence, the IDE hardware can only access the first 8GB of disk space. That means, if you use a hard drive that is larger than 8GB, it must be partitioned so that the first partition is slightly less than 8GB. 7.5GB is a good number to use. The OS gets installed there. The other partition can be the rest of the space (up to 128GB), and becomes accessible once the full OS takes over control.

    Contrary to what you may read elsewhere, this limitation applies to both Mac OS X and Mac OS 9 (and below). The only difference is that the Mac OS X installer checks to ensure the startup disk does not violate the 8GB limit for affected Macs; the Mac OS 9 (and below) installer does not check. As long as all system components needed during startup stay below the 8GB limit, everything will be fine. But as soon something needed during startup gets placed or moved above the limit, the Mac will stall during startup. The 8GB partitioning prevents this from happening.

    The largest drive size that is fully accessible is 120GB. However, if you happen to have a larger drive, you can use it. You will only be able to use the first 128GB of space. In fact, you should partition it so that the total of the usable partitions falls under 128GB. Doing so will stop the writing of files at the barrier, preventing disk corruption. The space above can be formatted as +free space+ in Disk Utility so that it does not get mounted.

    The firmware update for the tray-loader is here


    and you do not need to have Mac OS 9.1 to install it. 8.5 should be fine.
  • Allan Jones Level 7 (33,972 points)
    Hi Kenichi,

    You Wrote,

    and you do not need to have Mac OS 9.1 to install it. 8.5 should be fine.

    I thought this might be the case but, when I started looking for Apple references, they all said 9.1 or higher. Do you have a source that says FW can be updated from 8.5. If so, I'd like to bookmark it with my other references.

    Makes me wonder if this is one of those undocumented procedures that someone just discovered while spending time outside the box.

    This is good news for the OP as it is getting harder to find righteous retail install disks for OS9. And thanks for pointing out the 8GB partition. I suffered through that for years until I graduated from a Beige G3 (same ROM limitation) to the current MDD. How quickly we forget!

  • Kenichi Watanabe Level 7 (33,184 points)
    If you look at the article for the firmware update (1.2)


    software requirements is "none," meaning the original OS (as low as 8.1) is OK. Mac OS 9.1 is not mentioned. On the article for the slot loader's firmware update (4.1.9), it specifically says 9.1 is required.

    Also, if you look on this article


    the first two tables are for +233 MHz iMac using Mac OS 8.1+ and +233 MHz iMac upgraded to Mac OS 8.5+. Firmware Update 1.2 is listed as a recommended update. Since these iMac would only have 8.1 and 8.5, the firmware updater would have to run under Mac OS 8.x.
  • Allan Jones Level 7 (33,972 points)
    Thanks! I didn't look at the read-mes associated with the downloads. Duly noted!

  • John Scott1 Level 2 (310 points)
    I have a old tray loader and probably spent more then I care to admit on it. Plus it is very hard to find old OS versions of OS X which I will tell you right now is what you need to surf the web. No supported browser's (Firefox,Mozilla,Camino) support Classic (8.5, 9.2 etc) In fact most don't even support what I am running which is OS X 10.3.9. That's about as recent as your gonna get because OS X begain with DVD's with 10.4 no CD's. I guess maybe their was some DVD ROM tray drives but I cannot find any of them. I bought this Bondi Blue iMac from my wife's school. I bought it for $25. But I probably spent $250 getting it working OK. I put a 333mhz
    CPU logic board in it, added RAM, bought OS 10.1.1,then OS X 10.2, then 10.3.
    To be honest I should have just let it go at $25 and used the 9.2 classic and forgot about the rest.All I can say is thank god for EBay!
  • chichi1234 Level 1 (0 points)
    Can someone PLEASE help me. I just recieved a G3 iMac, and have absolutely NO clue about it. I am so used to windows based PC's. However, I was told that it needed a battery backup because it gets hungup after login, and must be rebooted....also, when unplugged from power source, you have to reset the date and time in what appears to be a "DOS" mode.

    I am not sure how to install a new connection for internet. Looks as if this has mozilla firefox browser installed. Any other little tidbits on what I can do with this machine will be a plus.....Thanks, Chi
  • Kenichi Watanabe Level 7 (33,184 points)
    If the PRAM battery is dead, you should replace it. It looks like this


    You should also specify which iMac model you have. The two basic types are the ones with a tray-loading optical drive and the ones with a slot-loading optical drive.

    You should also state if the iMac runs Mac OS 9 or Mac OS X.

    You should also start your own topic instead of tacking on to the end of an existing topic. Your question will be more visible for people who may want to reply. To do so, go to the forum (in this case)


    then click on the link toward to upper left corner that says +Post New Topic+.