Re: More on Mustek 8000SP adventures...

Rogier Wolff (R.E.Wolff@BitWizard.nl)
Fri, 25 Jul 1997 08:49:57 +0200 (MET DST)

becka@sunserver1.rz.uni-duesseldorf.de wrote:
>
>
> > I'm writing sane-support for the Tamarack SCSI scanner. I had the same
> > problem: my NCR810 driver would report an "NCR DEAD" when I tried to
> > scan a slightly non-trivial amount of data.
>
> > Initially I increased the timeout to one minute. However nowadays, my
> > driver simply reduces the scan-size to at most an inch at a time.
> > The Tamarack takes less than 10 seconds to scan an inch, so there
> > is no problem. This way I can run a standard kernel. (well almost).
>
> > Mustec maintainers: This might also be applicable for the mustec
> > backend....
> Well - I doubt the mustek will resume precisely enough (re-positioning with
> 1200dpi reolution at the presence of mechanical parts seems non-trivial to
> me) and it is already quite slow.
>
> However something a simple as decreasing the SCSI-buffer-length (or rather
> the requested length) might do the trick.

Well, that's what the Tamarack does. I don't have a mustek, so I don't
know what it actually does, but from all I hear, it is the same as what
the Tamarack does.

Not using the full SCSI buffer length is exactly what I was
suggesting.

The tamarack more or less scans at a constant mechanical speed. At
higher resolutions the datarate is simply higher. With higher
resolutions you easily hit buffer-size restrictions. At the lower
resolutions, a buffer simply lasts longer. That is how you can reach
"more than 10 seconds" transfers.

When you tell the scanner not to do more than 1" at a time, it will
require a new scsi command every 1". This gives the NCR chip time to
breathe. You will not give more than 10 unneccesary breaks per scan:
there are just 11 inches to scan.

Should you have other devices on the scsi bus, it would also be nice
if the others get a chance to the bus every ten seconds or so. I have
all my "only used occasionally" hardware on my scsi bus, so most of
the time the scanner is alone. But having a harddisk locked out for
more than ten seconds is annoying.....

Regards,

Roger.

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