> 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