RAM is certainly one. The biggest version of a NuBus machine is the server 9150, but the biggest common mobo is the 8100 or 8150. These have 8 RAM slots. Since the largest standard SIMM for these is 32 MB, that gives a max fit of 264 MB (including the 8 MB soldered to the mobo).
But there's worse. All of the NuBus PowerMacs use the PPC 601. This is really a hybrid - a transitional chip between the IBM POWER instruction set (from which the whole PowerPC thing was derived) and the "true" PPC instruction set embodied in PPC 603, 604, G3, G4 et al. As they stand, the NuBus PowerMacs have a compromised processor.
And don't forget the disks. NuBus PowerMacs use only 50-pin SCSI disks. They only support SCSI-1 on the mobo (that's
5 MB/s between friends). Not exactly speedy, is it? 50-pin HDDs bigger than 2 GB are getting as rare as hen's teeth. Yes I know that in theory you can bridge 68-pin SCSI drives to 50-pin buses but it never seems to work for me.
Then there are the issues over bus architecture. There are significant differences in the architectural structure between a Mac of NuBus vintage and one of PCI vintage - the latter all use Open Firmware to build the boot environment dynamically, for example. Also, a lot of Apple's NuBus-era technical data is proprietary, obscure or just plain lost from view.
For example: people have successfully ported BSD and Linux to many NuBus based 680x0 machines, but *not* to the Quadra 900 and 950 and the Mac IIfx. Why? Because these machines have specific circuitry to do fast-serial/DMA work, and it isn't (so far) worth the effort to try to figure that part out.
Likewise with the NuBus PowerMacs. Given the limited RAM, the crippled cpu, and the outdated bus structure, it isn't
really worth the effort to try to figure out how to persuade OS X to run on that vintage architecture. Linux has been done. There is a version of MkLinux available for NuBus PowerMacs. I don't think it gets much active support, though.
In the UK, you can now buy original PowerMac beige G3s (233 or 266) for around GBP 200. I don't doubt on ebay in the US they cost less. These can take standard (cheap) IDE hard drives and CD drives. You can stuff them with (cheap) PC100 or PC133 RAM - provided you check for a few technical gotchas. These G3s do a fine job of running OS X on a budget - not to mention BSD or Linux if it takes your fancy. Given all that, why try to force OS X on to NuBus Macs?
All in all, a NuBus Quadra is far more fun for the UNIX connoisseur than the NuBus Power Mac.
_____________________ A malicious aside:
Apple's CarbonLib was developed to provide a migration route for applications from the classic Mac OS to OS X. Although early versions of CarbonLib will run on OS 8.1, which itself runs on Quadras, the small print for developers tells a different story. CarbonLib is really only designed for PowerPC applications. All recent versions of CarbonLib are limited to OS 8.6 and later.
Applications suppliers have been more restrictive than this. For example, MS Office X is - in essence - a Carbon application suite. Without the OS X CarbonLib it won't run. In principle, it should run on OS 8.6. It refuses to. I can't see any technically valid reason for this. I bet MS Office X could be hacked to run on 8.6 if someone could do the hacking - but again, why bother?
Taking this further: Power Macs include an emulator to support 68K code; there is no implicit reason why one could not make an emulator for PPC code which ran on a 68K Mac. With the right degree of hackery, one should be able to make a CarbonLib application (say MS Office X) run on an earlier version of CarbonLib (say for OS 8.1) on a Quadra with a PPC emulator.
This would be cool.
But, I think, not useful...
GWW
On Thursday, Jun 12, 2003, at 20:26 Europe/London, Stacy J. Dunkle wrote:
I've heard that it's potentially possible, if someone's willing to do the hacking required, like what was done in XPostFacto.
But wow, why would you want to run it on a NuBus machine? The PCI
PowerMacs are bad enough with the 50mhz bus speed bottleneck, thus I
imagine 33mhz would be rather painful. Not to mention that you can't put
more than 256MB RAM in the NuBus machines, and I think that's only in
the 6100 series. Plus, no USB, Firewire, and basically no expansion
cards, as I doubt that even if someone were to make OS X install and
boot on a NuBus machine, I highly doubt they'd be able to get it to
recognise the NuBus expansion cards.
Stace
On Thu, 2003-06-12 at 15:01, Tom Tubman wrote:OS X requires Open Firmware and a PCI architecture AFAIK, so the NuBus machines are out.
- Tom
I would think that RAM would be a serious stumbling block. But still, if it'd work, I'd be all over that!
-James
Hello!
I'm curious to know if Mac OS X could possibly run on NuBUS-based PPC
machines (eg PPC 7100) If not, is it just impossible, or nobody has tried
yet?
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