Adam Fritzler <afritz@iname.com> wrote:
>  - NCR 5380
>  - SAB/Siemens 2797B-P
>  - SAB 8237A
>  - SCN8031HCCN40/M (KHJ4256) (Intel/Signetics/DEC)
>  - a cache chip, several drivers, etc.
>  - one EPROM: PN: 23-479E6-00 ((C)1989 DEC, ABOfy/w9123)
>  - a set of three DIP switches: set ON,OFF,ON
> 
> Part number on board: 5419288.  Name: 'SCSI/FDI ADAPTER L1' 
> 
> >
> >AND... Check to see that it'll actually fit inside the case and connect to
> >the mainboard.  Nothing much matters if the board doesn't fit :-)
> 
> And therein lies a great question...what does this board do?  It has no
> apearent connection to the motherboard, yet is a SCSI controller.  The only
> connectors it has are SCSI (male header), FDI (male header), and power
> (male).    What is the usefulness of a dual interface board with no
> motherboard connection?
> 
> Can someone ID this board for me?

Sure, I know this board very well (I have one). It is not a mass storage
controller for KA42. It does not connect to any motherboards, in fact, it is not
VAX-specific at all. It is a general-purpose board for attaching an FDD (3.5"
high-density, don't know about others) to a SCSI bus. Remember, the way they put
SCSI interfaces on "hard drives" nowadays is not how SCSI has always been
intended to work. It has always been intended that the actual drives have
physical interfaces like SA-400/450, ST-506/412, ESDI, etc., and SCSI has been
intended as a high-level interconnect bus like ISA or Q-bus. The intention has
always been to have controllers for the SCSI bus just like for ISA or Q-bus.
The board in question is one of those controllers, in this case for SA-400/450
FDDs. By the way, have you ever wondered why the original SCSI spec puts so
much emphasis on LUNs? Simply because the original intention has been that the
SCSI bus ID identifies the controller and the LUN identifies the drive on the
physical interface connected to that controller!

Sincerely,
Michael Sokolov
Phone: 440-449-0299
ARPA Internet SMTP mail: sokolov@alpha.ces.cwru.edu