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apple hardware stories

Chris Tillman wrote:
> On Tue, Oct 16, 2001 at 08:41:13PM -0400, Daniel Jacobowitz wrote:
> > On Tue, Oct 16, 2001 at 12:56:18AM -0400, Albert D. Cahalan wrote:
> > > An aborted attempt to switch? It makes no sense to even have
> > > the OpenFirmware code if it isn't used.
> >
> > Oh, it's used all right.  Reading the disk is one of those things it
> > just isn't used for, though.

Nor is it used for properly setting up the video controller.

> > They did a much better job their second time through the Open Firmware
> > mess.
> Has anyone ever thought about trying to re-burn the firmware in an OldWorld
> with the NewWorld version? Probably wouldn't want to risk a perfectly good
> box to debug it...

It doesn't work like that.  The firmware is closely tied to the
hardware underneath.  I don't know about new world macs, but the old
world macs hardware can be so flaky.  The hardware teams had a bad
habit of never really "finishing" the hardware, and often forced the
software guys to somehow "fix" it in the OS, no matter how ugly,
which was yet another reason why the 68K OS was so hard to port to
powerpc -- often times chunks of code that no one knew what they
did, and no one knew who wrote them, would cause the machine to not
run if it was removed.  I'll never forget when I was asked to
rewrite the SCSI driver to use polling instead of being interrupt
driven, because the interrupt bit would be set every time, but the
interrupt didn't always make it's way to the processor.  My clueless
manager (trite) told me to go ahead and try it.  Instead I went and
wrote a piece of code that proved that the DMA hardware was also
broken.  The hardware guys wouldn't even speak to me for a week
after that.


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