> I've got an hp300 with an external SCSI disk. After it goes through its BIOS
> boot sequence, and starts searching for a system, it finds my disk (which
> has NetBSD 1.1 on it), and the claims 'Bad Device State.'
> 
> If I put my hand on case & terminator on the drive at the same time, it will
> boot and work without any problems (I can remove my hand after it has
> booted). That
> is the ONLY way I can get this to boot. I've tried 3 different terminators.
> The SCSI cable I'm using came from a Mac, but I think that 'SCSI is SCSI.'
> 
> Advice? 

You have a ground loop, probably due to the difference in the voltage
base for the power supplies in the two cases: it is the difference
between signal and chassis grounds (and it's why RS232 uses a +/-11v
bias -- it can be generated with a +11/+22 using the +11 as the
boundry crossing reference).

Many old terminators had a grounding strap...

Are you grounding the computer case to the terminator, or the SCSI
enclosure case to the terminator?  You could safely ground-strap
the terminator in the second case to remove the need for your hand,
but the first case is more of a problem... you will need to remove
the connection between the signal ground and the chassis ground in
the SCSI connector, probably on the SCSI enclosure, or on the power
supply inside the encolsure.

Ground loops are a pain...


					Regards,
					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.