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salax54 · Oct 21, 2009, 11:34 AM

Hello folks, there's been a new "alternative" OS released a few days ago, namely MorphOS 2.4 for the G4 MacMini.
For those not familiar, it's an Amiga-genre OS, with lots of common items as the Amiga. You can read about it here: MorphOS � News Sadly, it's solely written for the PPC MacMini, but nevertheless, for Amigans it's a great deal. The reason being that there's not much development taking place for a while. Anyway, my question is a bit related to this Morph thing. I'd really like to understand what is it that makes an OS be bootable for a single type of Mac (Mini in this case) and not every PowerMac? Not talking about Intel and such, just PPC machines. For example, how can the OS X DVD be bootable for every G4 out there and not make exceptions between models? I believe the same goes for YDL, Debian etc. Is it something written for exclusive firmware? Maybe checking the firmware version before deciding to boot? It's strange that i can insert the MorphOS CD in the Mini and see it boot, and do the same on the MDD i got (plus various other G4's) and see nothing happening! How can someone achieve such a narrow range of compatible machines?
Thank you in advance!

ghporter · Oct 21, 2009, 01:38 PM

Booting relies on two things: the correct type of code for the processor being supported (machine instructions for PPC and Intel processors are VERY different), and that the code is formatted appropriately for the machine's boot mechanism-which again is very different for PPC Macs and Intel Macs.

Most Linux bootable CDs are aimed at Intel platforms; there are very different versions of Linux for PPC and Intel machines.

So it's not the "model" that's at issue, but the CPU that is the very heart of the computer.

Hope that helps.

salax54 · Oct 21, 2009, 03:13 PM

That's exactly what i'm saying. I understand that it isn't about differences between PPC and Intel. It's between the MacMini (G4) and PowerMacs (G4). You can try downloading the demo CD from the MorphOS site i mentioned. If you put it on any other PPC Mac than the Mini, it won't boot. So, it's actually something to do with the models, isn't it? Give it a try and tell me :-)

ghporter · Oct 21, 2009, 04:27 PM

The different "models" of computer are almost completely different, and frankly they are different enough that giving them the same name is a problem. When they went to Intel processors for notebooks, they changed the model names to avoid confusion (iBook is NOT the same thing as an "early MacBook"), but they didn't do that with the Mini. I may be nit picking, but that's the point-it's NOT a trivial issue. So "yes," different "models" of Mini (which differ in their processor brands) require different OS versions.

salax54 · Oct 21, 2009, 04:45 PM

My friend, i believe you haven't got the picture yet :-) I'm not saying something that has to do between the G4 MacMini and the Intel MacMini. I know they're two completely different machines. How can i make this more clear? All i'm saying is try booting the same cd with a PowerMac -any PowerMac that has the same processor as the old MacMini (G4) My main machine is an MDD dual 1Ghz G4. My MacMini is a 1.4Ghz G4. But i also have a few more G4's (digital audio, eMac etc.) They might belong to the same processor family, but only the MacMini boots the cd. I'm not talking about different models of MacMini, i'm talking about different models of Macs of the same (more or less) generation/architecture. I hope it's been clearer now...

ghporter · Oct 21, 2009, 10:03 PM

OK, I see what you're saying. (Thick head and busy day at work-sorry.) You SHOULD be able to boot any PPC-based Mac from a disc that boots your Mini. Can you provide exactly what disc image it is (a link to where it came from would be good) that works on the Mini but not on the other machines? This is very odd behavior.

salax54 · Oct 22, 2009, 04:13 AM

Yup, that's really odd! http://www.morphos-team.net/morphos-2.4.iso
You don't have to install it to check it. It takes you to desktop (if you can run it)

salax54 · Nov 3, 2009, 10:58 AM

Well have you given it any try? If you're curious, may i suggest a little reading here:
The Amazing MorphOS 2.4 G4 Mac Testing Effort!

ghporter · Nov 3, 2009, 01:54 PM

I haven't tried it because I don't have a PPC Mac to play with. I'm hoping someone who does have a PPC machine tries it and lets us both know.

Big Mac · Nov 5, 2009, 01:13 AM

Originally Posted by ghporter

OK, I see what you're saying. (Thick head and busy day at work-sorry.) You SHOULD be able to boot any PPC-based Mac from a disc that boots your Mini. Can you provide exactly what disc image it is (a link to where it came from would be good) that works on the Mini but not on the other machines? This is very odd behavior.

It isn't odd if the drivers for this alternative OS aren't present for the other kinds of hardware; even if it works on one G4 model doesn't mean it will work on all G4s. Of course, if it works on the mini it shouldn't be hard to get it working on other Power Macs.

ghporter · Nov 5, 2009, 08:25 AM

To me it sounded like the OP was not getting the disc to boot at all-maybe this is a problem with terminology more than hardware compatibility. At what point in the boot process does an Open Firmware/PPC Mac start needing drivers? It could be that it's a lot earlier than he (and I) assume, and the boot disc only includes drivers for the Mini's hardware. That would make a lot of sense.