Thanks, Andreas!  Very informative.

Scott Birdwell
DeFalco's Home Wine & Beer Supplies
[email protected]
www.defalcos.com

On Jan 21, 2013, at 6:24 AM, [email protected] wrote:

> I know you’ve already gotten your answer, but this seems noteably to me:
>  
> Intel Mac graphics cards have an EFI based firmware on them, so they are 
> compatible with the EFI based Intel macs. Otherwise the graphics card is 
> identical to a Power Mac or PC version.
>  
> Power Mac graphics cards have an Open Firmware based firmware on them.
>  
> And PC graphics cards have BIOS based firmware on them, or newer cards maybe 
> also have an EFI-aware firmware as well. But it’s propably different from the 
> one used in Intel Macs.
>  
>  
> IF you can find an Open Firmware based firmware for that specific card, you 
> can try to flash it. If none is available there is now way. And flashing is 
> not so very trivial either.
>  
>  
> One thing is interesting though: I’ve once used a PC version of a graphics 
> card in a Power Mac computer. Due to the BIOS based firmware, the computers’ 
> Open Firmware was unable to initialize it and the screen stayed dark. I 
> booted 
> into Linux (because that is what I used back then) and the Linux kernel 
> detected this PCIe graphics card and loaded the appropriate driver and with 
> it 
> the card was initialized. So, once the operating system took over, it all 
> worked even though it was the wrong firmware on the graphics card.
>  
> On Mac OS X the graphics driver will not work though, because it has built-in 
> logic to check for certain Open Firmware variables (or EFI variables, if 
> you’re on Intel). In other words, it relies on Open Firmware (or EFI on 
> Intel) 
> to initialize the card and takes over from there. Mac OS X will therefor 
> never 
> work with an identical graphics card that has the wrong firmware on it.
>  
>  
> Just to make things more complicated, I guess…
>  
> Cheers,
> Andreas aka Mac User #330250



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