> > Well, then why do they claim the SprintScan 4000 is a SCSI II
> > device, when it is only a SCSI I device? The SCSI chip that
> > they use is only capable of asynchronous transfers, and SCSI
> > II requires synchronous transfers. SCSI II uses the high density
> > D connector, and the SS4k uses the old Centronics style SCSI
> > I connector.
> A copy of the SCSI-II spec is on:
> http://www.uni-mainz.de/~tacke/scsi/SCSI2
> Chapter 5 shows that the Centronics-style connector
> certainly conforms to SCSI-II.
But that exact same connector is in the SCSI I spec. That doesn't make
this a SCSI II device...
> Chapter 6 shows that synchronous transfers are
> optional (and no other film scanner I've used supports
> or needs synchronous transfers).
And again, the SCSI I spec shows asynchronous transfers...so that doesn't
make this a SCSI II device either...
> The SprintScan 4000 also conforms to the command
> formats described in this spec.
And, again, the SCSI I spec has all the same command formats that this
scanner uses...not making this a SCSI II device. There is nothing that
makes this scanner a SCSI II device.
In fact, here's the clincher:
The SCSI controller is a Zilog Z53C8003VSC. The data sheet is here:
http://www.zilog.com/pdfs/serial/z5380.pdf
It clearly states in the data sheet it supports SCSI spec X3.131-1986.
That is unquestionably the SCSI I specification. SCSI II wasn't even
invented at that time.
Go look at SCSI cables. Centronics style SCSI cables are listed as SCSI I
cables. HD 50 cables are listed as SCSI II cables (as well as HD 68 cables
for wide). It's just common knowledge that Centronics and asynchronous is
SCSI I, and HD and synch is SCSI II. I don't believe you'll find a SCSI
chip that claims to be SCSI II that does asynch transfers only...they all
support synch transfers. They have to support asynch transfers solely for
backwards compatibility with older asynch devices.
In fact, any scanner designed not to use synch transfers is wasting SCSI
bus bandwidth. But, for some odd reason, the designers believe they should
be the only device on the SCSI bus...and that's bad/lazy engineering in my
opinion. I guess their expertise is in scanners not SCSI...which is a
storage standard. It's kind of like letting networking guys design storage
systems, or letting storage guys design networking systems. They don't
really get it quite right...
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