On Thu, 26 Jul 2001, Michael Jeffrey Tucker wrote:

> On Thu, 26 Jul 2001, Michael Wolfson wrote:
> 
> > In the first generations of PowerMacs that had IDE busses, Apple didn't
> > intend to use the slave.  That's why they had two busses -- one for the
> > hard drive, and one for the cdrom.  Around the time of the Beige G3's
> > (ISTR), they changed their IDE chipset so that it could use slaves in
> > MacOS, and could boot from slaves.  I think there were a few IDE wrinkles
> > up to the time of the blue and white G3's

	Any IDE based Mac before the Beige G3 cannot support slave devices
under MacOS. There are two revisions of the logic board for both the
(original) B&W G3 motherboard and the Beige G3.

	Rev 1 Beige G3's have Rage IIc+ onboard video chips and cannot
support slave IDE in MacOS without swapping out the original Rev A ROM
DIMM with a Rev B or later DIMM. (Note: NetBSD will work with the slave
devices once the kernel is loaded regardless of the ROM DIMM version) I
should also note that if you have a B revision ROM or later, the MacOS ROM
CAN boot Classic MacOS from a slave IDE device, but OpenFirmware (And
MacOS X) cannot.

	The Rev 2 Beige G3 motherboard has Rage Pro based onboard video and
supports slave IDE in its stock configuration. As it has a Rev D(?) ROM
DIMM. You can also use Apple System Profiler to look at the ROM versions
and/or the video card type. http://www.macsales.com has a page in their
support library that has pictures of each ROM DIMM so you can identify it
by sight.

	The Rev 1 original B&W G3 (Yosemite) is identifiable by only
having one bracket for a hard drive in the lower mounting tray in the
bottom of the case.

	The Rev 2 B&W G3 has a dual drive piggy back lower drive tray in
which you could mount a second hard drive ontop of the OEM drive. (There
is a TIL artical on this with pictures on Apple's Microsoftesqe Knowledge
Base. It so closely resembles Microsoft's Knowledge base that I'm getting
internal server errors when I do a search. It may possibly be able to boot
from slave, never heard a success story.

	NetBSD can usually handle master/slave IDE devices even on
machines that MacOS can't support them. The problem is getting the machine
booted. And retaining MacOS on the same machine. Usually your best bet is
to use a small SCSI drive as root or compile a custom kernel with root on
wd1a hard coded into the config file and boot from an ISO
CD-ROM/SCSI. Someone once said they set up a compressed kernel that booted
from a floppy, but it takes like 3 minutes to read a kernel from floppy in
OpenFirmware.

	The really new machines might support slave booting, but I've not
seen any reports of anyone having tried it. Even the Slot loading iMac
DV's have two IDE channels (Running on a _single_ ribbon cable no less),
and putting a second hard drive in an iMac would be, 
well...interesting. Perhaps the newer G4's can. Has anyone tried with a
Sawtooth G3/G4,G4 Digital Audio or Quicksilver yet?

	As for jumper settings, rememeber that Western Digital HD's do not
have the jumper installed in single drive configuration. (and will not
work properly set to master even when it is the only drive in the
system) You need to jumper it properly if you have more than one drive on
a chain; or remove the jumper, or set it to the neutral position indicated
on the drive cover. Feel free to try yourself, I've spent many hours
trying to get my Beige G3 to boot from slave in OpenFirmware with no
success. OpenFirmware just doesn't know about ide0/disk@1, though it
probably wouldn't be too hard to teach it if you knew Forth and lots about
its IDE controller.


	Chris