Dock II, internal IDE, external SCSI...boot off SCSI!??? how!???

["Derek V. Chan" <chan4@husc.harvard.edu>]

Okay, here's the deal:

TP750C/36 Mb RAM
340 internal HD

Dock II w/ internal IDE HD
External SCSI HD on ID#0

I can't boot off the SCSI even after setting the BIOS to boot HD#3 in the
startup options. If I disconnect the Dock II's IDE and set the BIOS to boot
HD#2, I can boot off the SCSI drive w/ no problems. ARRRRGH. Why can't I
boot off HD#3????  IBM seems to indicate that I can boot off any of the HDs...