iMac4,1 and iMac5,1 Firmware Tool Released

[MacEFIRom]

I was asked by a couple of fellow forum members to write a firmware tool for the iMac4,1 and iMac5,1. This model was the first iMac introduced with an Intel processor in 2006, and they later updated the platform with Core 2 Duo CPUs. The iMac4,1 came with the Core Duo processor, which was limited to 2GB of RAM, and was only a 32 bit CPU. The iMac5,1 came with a Core 2 Duo CPU, and can take 4GB of RAM, and is a 64 bit platform, even though the kernel can only boot in 32 bit due to 32 bit EFI. A lot of people have upgraded their CPUs, but are still stuck with the 2GB RAM limit and have to hack Lion to get it to run. This firmware upgrade removes the 2GB RAM limit, properly identifies the Core 2 Duo CPUs, and Lion will install and run just fine. The core file set has been tested by a forum member (Thanks Martin), and while I don't have an actual iMac to test on, the files created for the firmware upgrade perfectly match the core file set that has already been tested. As usual, you can upgrade or downgrade at will. If you have a CPU in an iMac5,1 that isn't supported in the iMac4,1, the system will not boot after the update until a compatible CPU is installed. The program checks the iMac model and will only install the iMac5,1 firmware on an iMac4,1, or the iMac4,1 firmware on an iMac5,1, whichever is appropriate. If you have an iMac5,1 the program will warn you about downgrading, but will still allow the firmware update. The download does not contain any firmware updater files or image files. The program creates a small RAM disk, downloads the needed files, copies all of the scripts to the RAM disk, and then runs the scripts. Everything is left on the RAM disk for you to look at and study, if needed.

There have also been requests for a MacMini1,1 and MacMini2,1 firmware tool, and although there doesn't appear to be a MacMini2,1 firmware image in any of the Apple provided downloads, I'm looking into the feasibility of extracting an image using a tool in the rEFIt package, so stay tuned.

I hope you enjoy the benefits of extending the value of your iMac4,1, or being able to change your system back and forth for development purposes.

[epromer]

Thx a lot! I have a mini late2006 and I'm eagerly to remove the 2GB of RAM limit. Keep going!

[SummerSoFar]

Thank you! Thank you! Thank you!  

You just breathed new life into my iMac 4,1 (upgraded to Core 2 Duo and a SSD).

I continue to be amazed how my 5+ year old machine continues to be a relative speed demon with minimal ongoing effort and cost. Your awesome little tool extends that even further.

Like I said -- Thank you!

I will make the firmware upgrade this weekend, and will report how it goes.

Just curious -- I also own a MacBook 1,1 that also has the 2GB limit and is not supported by Lion. I know that the Core Duo proc is not upgradable, but do you suppose that the firmware on it could also be upgraded to lift the memory limit and/or fool the Lion installer???

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Edit 09/10/2011

I am very pleased to report that my iMac is working perfectly post upgrade. Woot woot!

Some thoughts:
I first had tried running the tool while in Safe Mode, thinking that would be best to minimize any potential conflicts. But upon install and reboot no EFI upgrade was performed. Not sure why that is, but after performing the install again in regular boot mode, closing all open apps and disabling Little Snitch beforehand, upon reboot the firmware upgrade process kicked off as expected.

The machine booted to the desktop, and System Prefs now successfully reported it as a iMac5,1. However, both the network and the airport cards were no longer recognized (all other hardware looked okay). Luckily, performing another reboot solved this issue.

Just to be safe, at that point I used Kext Utility to clear the kextcache, and ran Applejack in SU mode to rebuild permissions and clear other caches. I also fired up Hardware Monitor -- all sensors and fans continued to be well within spec.

Everything seems to be working beautifully. There was an annoying bug with these machines that prevented the Mac Aluminum keyboard from working at startup and in SU mode, and now that is even fixed!

I have not yet tried purchasing or installing Lion, or installing 4gb of memory, but I only assume that those will work now without issue as well.

The only strange and new activity I see is a hidden volume called FirmwareSyncd getting automatically mounted and unmounted on occasion. Any idea what this is, and what it is doing?

Thanks again to MacEFIRom for providing a bloody brilliant tool to extend the life of our 1st gen Intel iMacs. Your time and talent in doing so is greatly appreciated!

And I'll sheepishly ask again -- Is there any hope in getting my Macbook1,1 Lion compatible as well?  

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Edit 09/19/2011

Today I was successful in installing 4GB of RAM, with System Profiler recognizing 4GB installed.

Still have not tried installing Lion, however more recent reports later in the thread make it seem like that may still be a challenge to do...  

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Edit 10/02/2011

Confirmed that MAS still does not allow the purchase of Lion.

I assume that the (overpriced) retail copy of Lion (on the flash drive) would work.

[xi1inx]

I confirm the Firmware 4GO upgrade on my iMac early 2006 20". This is a milestone MacEfiRom!

Just see the picture to have proof!

For the Macbook and Macbook Pro 1.1, a firmware upgrade will allow ram upgrade but not for cpu. Cpu is soldered on the logicboard.

  17 september news :

Upgraded my cpu to a C2D T5600 which is cost less than the t7xxx series cpu's. This bring all the C2D goodness to my iMac with little less L2 cache.

Attemping to install Lion on my iMac updated with this firmware update. Lion installer tell me the os cannot be installed on this computer. Add my logicboard model (Mac-F42787C8 DVT) in all the plist's on /system/library/coreservice/ but don't work.  I suppose we need to modify the logicboard model embedded which is embedded in the EFI. This is the next step.

[nshuman]

Wow, I have a nice 20 inch iMac 2006 that is stuck at 2GB of ram and 32 bit. I guess I have to look into all of this. Time to search for a CPU...

[wpnelson44]

Is is possible to modify this firmware update to work on an iMac5,2 as the 5,2 only accepts 2 megs ram.

[takadkc]

I successfully upgraded my imac from 4,1 to 5,1, and from core duo to core 2 duo.  See below.  Yet, when I go to the Apple Store to try and download Lion, it says my computer is not compatible and refuses to download.  Is it checking something besides model identifier = 5,1?

thanks!


Hardware Overview:

  Model Name:   iMac
  Model Identifier:   iMac5,1
  Processor Name:   Intel Core 2 Duo
  Processor Speed:   2.33 GHz
  Number Of Processors:   1
  Total Number Of Cores:   2
  L2 Cache:   4 MB
  Memory:   2 GB
  Bus Speed:   667 MHz
  Boot ROM Version:   IM51.0090.B09
  SMC Version (system):   1.1f5
 

[Newflesh]

I successfully upgraded my imac from 4,1 to 5,1, and from core duo to core 2 duo.  See below.  Yet, when I go to the Apple Store to try and download Lion, it says my computer is not compatible and refuses to download.  Is it checking something besides model identifier = 5,1?

thanks!


Hardware Overview:

  Model Name:   iMac
  Model Identifier:   iMac5,1
  Processor Name:   Intel Core 2 Duo
  Processor Speed:   2.33 GHz
  Number Of Processors:   1
  Total Number Of Cores:   2
  L2 Cache:   4 MB
  Memory:   2 GB
  Bus Speed:   667 MHz
  Boot ROM Version:   IM51.0090.B09
  SMC Version (system):   1.1f5
 

It is because we keep the same board ID(i find it with geekbench) :

Apple Computer, Inc. Mac-F42787C8 PVT

Everything work fine for me.

[Newflesh]

I confirm the Firmware 4GO upgrade on my iMac early 2006 20". This is a milestone MacEfiRom!

Just see the picture to have proof!

For the Macbook and Macbook Pro 1.1, a firmware upgrade will allow ram upgrade but not for cpu. Cpu is soldered on the logicboard.

Are you sure that the system really use 4Go(activity monitor for proof)

Thanx

[katman]

Is is possible to modify this firmware update to work on an iMac5,2 as the 5,2 only accepts 2 megs ram.

I'm in the same boat. I have a late 2006, 5,2, 17" 1.83ghz, school edition. I am running 10.7.2 and bootcamp just fine. I would like to add 4or even 8 gig of ram. On another note, is there a way to increase the ram allocated to the 950 video so that I can run Final Cut Pro?

[stinkymr]

Might this be possible for the iMac4,2 as well, please? Thank you!

[timalf]

I successfully upgraded my imac from 4,1 to 5,1, and from core duo to core 2 duo.  See below.  Yet, when I go to the Apple Store to try and download Lion, it says my computer is not compatible and refuses to download.  Is it checking something besides model identifier = 5,1?

thanks!


Hardware Overview:

  Model Name:   iMac
  Model Identifier:   iMac5,1
  Processor Name:   Intel Core 2 Duo
  Processor Speed:   2.33 GHz
  Number Of Processors:   1
  Total Number Of Cores:   2
  L2 Cache:   4 MB
  Memory:   2 GB
  Bus Speed:   667 MHz
  Boot ROM Version:   IM51.0090.B09
  SMC Version (system):   1.1f5
 

It is because we keep the same board ID(i find it with geekbench) :

Apple Computer, Inc. Mac-F42787C8 PVT

Everything work fine for me.

So is there any way to get a Lion compatible board ID in there or am I screwed once again trying to get Lion installed?!
...and btw, thanks MacEFIRom for the great utility, that at least for a while brightened up my evening

[netkas]

boot your mac with chameleon, you can fake there you board-id via smbios.plist, check another thread for chameleon on mac

[xi1inx]

It is possible to mod the embedded logicboard id? 

I'm able to boot my hackintosh drive on Lion with last chameleon. But I lost accelerated video. My Ati X1600 is now downgraded to 6MB! 



Look at the prtscrn
 
Another test: I'm able to boot on usb key with Lion Install files on it with Snow Leopard Kernel. With the Lion one, flashed iMac won't boot on it.

[cpl593h]

Hello,

The MacBook2,1 has a C2D CPU. Its EFI implementation is 32-bit though (better explained here) and it prevents, amongst other things, a smooth installation of Windows 7 64-bit (you have to remaster the DVD before it even boots).

It looks like MacBook3,1 (Santa Rosa) have a far better EFI implementation. I was wondering if what you've done for older iMacs would be achievable for older MacBooks too (I understand that MacBook1,1 is not possible due to the soldered CPU, but MacBook 2,1 has the right CPU and just suffers from an ugly EFI implementation).

Thank you!