grant@torque.net
Sun, 17 Jan 1999 10:55:37 -0500 (EST)
ATTENTION core parport folk: lets try to put together an information
sheet for the web pages that addresses this issue ...
> i'm searching a driver for an EPP-scanner to use with linux. Is there
> something out there?. Please help me.
Here's what I know:
(1) http://www.mostang.com/sane/ contains lots of information about
scanner drivers. If a user-land driver for a specific PP scannner
exists, you'd expect to find it here.
(2) Some parallel port scanners (HP, Microtek) are known SCSI devices
with integrated parallel port SCSI adapters. In some cases we
know what the adapter is and work is in progress to develop a
Linux kernel driver for the adapter. When those drivers are ready
it _should_ be possible to use the SANE applications with the
Linux 'sg' interface to access the devices.
(3) It should be possible to reverse engineer the protocols of some
of the other PP scanners, but to do this we need a method for
collecting traces. In theory, it is possible to write a Windows
VxD (somebody correct me if I've got the concepts messed up, I
know very little about Windows' architecture) that would trap all
accesses to the parallel port and log them the way DOSemu is able
to do. But, we don't seem to have found anyone with the will and
the knowledge to write such a tool for us. (I'm sure such a thing
actually exists, but it is probably quite expensive.) A more
expensive approach would be to find a high-end logic analyser that
can capture samples on 18 channels at about 2M samples per second
and store at least a minute's worth of samples ;-)
Finally, there's some hope that WINE will eventually be able to
load and run the manufacturers' VxD files. When that happens,
we can use it to capture traces. In the meantime, there doesn't
appear to be any way to get traces for devices that come with
Windows-only drivers.
Progress does happen though: a couple of years ago it wasn't possible
to trace a lot of devices with DOSemu because of some timing problems
but some ingenious work eventually resolved that and the result is
that many of the parallel port Ftape drives are now supported by
Linux.
(4) The correct approach, of course, is to pressure the manufacturers
into releasing specifications so that we can write drivers for their
devices. While support seems to be improving in some areas (Creative
Labs has recently decided to help with the development of Linux
drivers for their PCI sound cards, for instance) there's no sign
that any of the scanner manufacturers are willing to release their
specs.
There may be some things that I've missed here, but perhaps some of the
other members of the list that have been around this would care to
expand on or correct my comments so we can get a document to put up
on the linux-parport homepage.
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Grant R. Guenther grant@torque.net
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