On 1/22/2014 5:14 PM, clipka wrote:
>> Well, that's only in so-called "IBM PC-compatibles". (How compatible are
>> any of these with the 30-year old dinosaur?) I think the Apple Mac does
>> it differently...
>
> I'd be surprised if Macs came without A20 line gate. After all, it's the
> type of logic that's needed for IBM PC-compatibility but has been moved
> from discrete gates on the mainboard into the chipset decades ago already.
>

I thought that, some time back, the only "functional" difference between 
Mac and PC had finally come down to an extra chip on the board, which 
basically prevented the OS from booting, if it wasn't on a machine that 
had it, and.. I am guessing the GUI functionality isn't in firmware/ROM 
anymore, right? But, there was a whole huge thing with trying to get PC 
stuff to boot on a Mac, and a Mac to boot on standard PC hardware, and 
it all came down, not to architectural differences, so much as just, 
"There is this extra chip on the board."

Or, maybe I was just imagining that?

-- 
Commander Vimes: "You take a bunch of people who don't seem any 
different from you and me, but when you add them all together you get 
this sort of huge raving maniac with national borders and an anthem."

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