>  When one talks about FWSCSI on MPE, one is really talking
> about Fast Wide
> Differential (AKA HVD High Voltage Differential) SCSI, as
> opposed to Fast Wide
> Single-ended (AKA LVD or Low Voltage Differential)SCSI.

SE is LVD???

> All this to say that if your DDS-4 drive is a Differential
> SCSI drive, you
> should be able to connect it to the FWSCSI.  If it is not
> differential, DO NOT
> CONNECT IT, its controller will get fried.

Actually, it won't. Differential (HVD) devices automatically disable
their line drivers if they sense ground on the DIFFSENS line, which is
grounded by SE devices (or, perhaps more properly, DIFFSENS is used as
an active-high enable). Mixing SE and HVD (and LVD, for that matter)
on a bus won't hurt anything; the HVD devices will disable themselves,
and the LVD devices will operate in SE mode.


Steve Dirickson   WestWin Consulting
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