[G4] Mixing internal drives

[JayB]

Mine:  500 APG (sonnetted up to 1gig)
1 gig ram.

Built @ Apple with 2ea internal 18gig Ultra SCSI drives.

I had used one drive as OS X Panther boot and the other as OS 9.2  
boot.  (Yeah, I've been MAC for coming up on 2 decades and I tend to  
drag a bunch of legacy software along until ..... I can't).



One SCSI died.  On advice I got here, I bought a Maxtor 100G ATA  
(it's really a 112Gigs) and plugged it into the Ultra ATA port on the  
motherboard.  Couldn't see the drive until I booted from OS 9.2  
Install CD.  I initialized and then booted from the Panther Install  
CD and couldn't reformat or install until the 3rd attempt.  Got  
Panther on it and loaded PhotoShop CS2.  I'd get a freeze by the time  
I got 3 clicks into ANYTHING.

Finally, I pulled the plug on the SCSI drive and normal behavior ensued.

Question:  Is the trouble because the bus doesn't like having BOTH  
ATA and SCSI on the bus?  Or is it because the combined gigs is  
beyond 128?  Or something else?

If I boot under the SCSI (OS 9), it works fine.  But if I boot the  
ATA (OS X) it will freeze up (unless I open up and disconnect the  
SCSI cable from the PCI card).

Any informed suggestions would be appreciated.

~Jay