On Wed, 12 Nov 1997, Allen Briggs wrote:

> > It seems to me that the hardest part of supporting IDE on Mac would be
> > figuring out how the interrupts are handled.  After figuring out these
> > two unknowns, it should be a matter of compiling the wd driver into
> > the kernel..., shouldn't it?
> 
> Nope.  I highly doubt that Apple used a standard IDE chip/cell.  Maybe
> they did, but I really expect that they designed their own.  "to keep it
> cheap"
> 
> -allen

If its any help, the Quadra 630 was the first desktop to impliment IDE
(the PowerBook 150 being the first portable).  The Q/P630 IDE circuitry
doesn't support *any* extended PIO or DMA modes.  The most recent IDE
circuitry that Apple has been doing *does* support many of these modes. 
The IDE in the PowerBook 150 was so non-standard that Drive Setup cannot
reformat that drive, a seperate drive formatting program from Apple is
needed just for that computer.  Last I heard, Apple wouldn't release their
specs on IDE to FWB Software so they could optimize their drivers.  I once
tried the FWB drivers, and they were as much as 50% slower than Apple's!
I don't think IDE is going to be an easy thing to support.  But I'd love
someone to prove me wrong. :)

--
Nathan Raymond
nate@staff.feldberg.brandeis.edu
xray@cs.brandeis.edu
http://www.cs.brandeis.edu/~xray