> Software person now doing hardware due to budget cuts seeks a
> moment of
> hardware guru's time for walk through SCSI land. SCSI,
> SCSI-2, Single Ended
> (SE), Fast Wide (FW) and Fast Wide Differential (FWD) -
> tra-la, tra-la.

SE: TTL-level signals referenced to ground; speeds from 5Mhz to 20MHz
Differential, a.k.a. "HVD": something around +/-12V signals on paired
wires (old-timers think "EIA 20mA current loop"); same speeds as SE
LVD, a.k.a. "Ultra2": TTL-level differential; 40MHz clock
Ultra160: same as LVD, data signals double-clocked, i.e. transfers on
both clock transitions, like DDR DRAM

LVD & Ultra160 can co-exist on the same bus with SE devices, but will
operate in SE mode. HVD doesn't co-exist with anything else.

> 12H manual says external bus to which it is connected needs
> to be SCSI-2
> Fast Wide Differential (FWD), 68 pin high density connector.
>
> The 9x8s all have external SCSI drives connected through the
> "SCSI Console
> LAN" card. Which is SCSI Single Ended (SE)? 50 pin high
> density connector.
> Two of the boxes also have a second half width "SCSI SE
> Parallel" card. All
> SCSI-DAM's in Sysgen are configured as "A1703-60003-SCSI". I
> can not pull
> any of the cards at the moment to get actual part numbers
> since other people
> are on all machines so I can not bring them down right now..

Both CONSOLAN and the half-height SCSI/Centronics cards are SE SCSI.

> So will this work? Can I connect the 12H SCSI-2 FWD to the 9x8
SCSI-SE
> busses?

Nope. At least not without an SE/Diff adapter.

> If so, what are the ramifications. If not, what do I
> need in the way of new SCSI cards?

HP makes full-height differential scsi cards for the 9x9 series; don't
know about the 9x8s.

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