Re: Scanner
> So why is it that parallel port scanners don't tend to be supported, but
> their SCSI cousins are. I wouldn't think that there would be that much
> difference between the hardware on a SCSI scanner vs a parallel port
> scanner.
No, the difference is all in the interface. If your scsi adapter
is supported then communication with *any* scsi device is
supported too. Supporting special devices like scsi scanners may then
be done by a usermode program using the scsi generic interface.
Writing such a usermode program is easier than changing the kernel.
Parallel ports are worse, you may have to write a kernel driver
in order to support whatever protocol the parallel scanner use.
This is harder, fewer people know how. There is a generic
interface to the port, but it isn't necessarily good enough.
The timing might be too strict for a usermode program.
Parallel communication with things other than printers isn't
standardized the same way scsi is standardized, that's why a
generic parallel driver isn't as successful. It is
usually "hacks" for those too cheap to buy even a
cheap scsi card, and there usually aren't much tought or quality
engineered into the cheapest products. So supporting them
is harder.
Helge Hafting
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