Subject: Re: confused
To: Paul Duncan <>
From: Stan Pietkiewicz <>
List: port-vax
Date: 01/22/1999 23:38:09
Paul Duncan wrote:

> Hi again,
> Sorry for this rash of messages from this VAX newbie, but I've got the boot
> prompt up and I've been examining the system. I can hear a hard disk spin
> up, but when I do "show scsi", no devices are shown. If I do "show device",
> this is what comes up:
> DSSI Bus 0 Node 3 (R1A12A)
> -DIA3 (RF31)
> DSSI Bus 0 Node 7 (*)
> UQSSP Disk Controller 0 (772150)
> -DUA0 (RA81)
> UQSSP Tape Controller 0 (774500)
> -MUA0 (TU81)
> -MUA1 (TU81)
> Ethernet Adapter
> -EZA0 (08-00-2B-28-47-C2)
> Is this DSSI bus something like a DEC SCSI equivalent? There's a flying lead
> coming out of the front panel with a 50 way centronics style connector on it,
> and I had thought this to be SCSI, was I wrong. In the top left of the
> front panel there's what looks like one of these new style D type SCSI
> connectors with the blade-like pins, what's that? There are no tape drives
> on the system, so I guess this is just an unused Tape Controller that it
> mentions which can control up to two drives?
> Any more insight would be welcomed! :-)
> Paul
> ~~~~
> `

DSSI is a DEC proprietary interface; I got fooled with it  too..
The connector that looks like a SCSI Mini-50 is a DSSI connection to an external
expansion chassis. You do have terminator on it, yes???

DSSI can handle (AFAICT) 7 devices + 1 controller on a bus. There supposedly were
performance advantages to DSSI over SCSI....

IIRC, the RF31 is ~300MB....and VAX/VMS would easily fit on it.....