Earliest OS for an iMac G5.

[sjpetry]

I was wondering what is the earliest OS I can put on my iMac G5. Is it possible to get OS 8 on it or earlier?

My motive is of just plain curiosity.

Thanks. :)

[Sun Baked]

Don't you wish you could just reach out and...
http://forums.macrumors.com/attachment.php?attachmentid=3171

The earliest OS you can use on any Open Firmware-based machine is the OS that shipped with it. :rolleyes:

[rdowns]

I can make you a great offer for System 7.5. I'll throw in a copy of DOS 6.2.2 and an unopened copy of Bob. :rolleyes: :rolleyes:

[sjpetry]

Just asking a question.

[dotdotdot]

The iMac G5 rev. A only works with Panther and above and Rev B with Tiger and above - Apple locks the hardware so you cant install earlier versions - although I have no clue why anyone would not want the latest version of an OS...

"I got Windows XP! Want it?"
"No thanks man, I'm cruisin' on my MS-DOS"

[AppleAce]

I think I remember reading that a G5 chip, even if it was not locked from installing earlier versions of system software, will not boot OS 9 or anything earlier. I think the reason for this is that there are a couple routines in the boot process for OS 9 that were still written in 68K assembly, so every power PC chip had to have a small 68K emulator in rom, and this architecture was not included in the G5. Can someone confirm this, or am I just making things up?

[wrldwzrd89]

I think I remember reading that a G5 chip, even if it was not locked from installing earlier versions of system software, will not boot OS 9 or anything earlier. I think the reason for this is that there are a couple routines in the boot process for OS 9 that were still written in 68K assembly, so every power PC chip had to have a small 68K emulator in rom, and this architecture was not included in the G5. Can someone confirm this, or am I just making things up?
It makes little difference, since the later G4 machines (like my iMac) are locked in much the same way from booting Mac OS 9 or earlier.

[mkrishnan]

The iMac G5 rev. A only works with Panther and above and Rev B with Tiger and above - Apple locks the hardware so you cant install earlier versions - although I have no clue why anyone would not want the latest version of an OS...

As little sense as running OS 8 on an iMac G5 makes... :rolleyes: doing exactly this is very common in corporate settings... It is very, very common for a company to buy new Windows machines that have XP installed on them and re-image them to Win2k to maintain a common deployment. Compatibility and keeping IT support simple are the reasons.

For instance, not that our IT department is really deploying new Macs, but SPSS is used by almost everyone in our department, and it doesn't work on Tiger. If they needed to replace a dozen computers today, there is no way they would say, okay, we can't run SPSS on these....

Similarly, what if you had a grid of XServes and one of them broke...are you really going to run your grid with 1023 machines on Panther Sever and one on Tiger Server?

So is it really true that a Tiger pre-installed Mac will not even run Panther? That seems a lil' on the crazy side to me.

Bleh, that's all corporate concerns though. Me, I upgraded even though I knew SPSS would get b0rk'd. :D

[ijimk]

just curious sjpetry why are you asking this? :confused:

[yellow]

The earliest OS you can use on any Open Firmware-based machine is the OS that shipped with it. :rolleyes:

Actually, that's not fully true. When the AlPBs first started coming out with Panther installed, I erased it and installed Jaguar. It still works fine to this day.

But going to OS 8 is a bit of a stretch..

[sjpetry]

just curious sjpetry why are you asking this? :confused:I just wanted to know if it is possible.