Date: Thu, 11 Jan 1996 21:29:12 -0500 (EST) From: Peter Dufault <dufault@hda.com> To: terry@lambert.org (Terry Lambert) Cc: peter@jhome.DIALix.COM, hackers@FreeBSD.org Subject: Re: SCSI Scanner anybody? Message-ID: <199601120229.VAA04817@hda.com> In-Reply-To: <199601111923.MAA17804@phaeton.artisoft.com> from "Terry Lambert" at Jan 11, 96 12:23:30 pm
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> > I guess this is going to be a "You gotta be kidding me!" type question, > > but does anybody know what would be involved in driving a SCSI scanner > > (eg: something like an Epson GT-8500, HP Scanjet 3C, Sharp JX330 etc) > > There are drivers. > > The main limitation is that the SCSI controller in your machine must > be able to operate in target mode for several SCSI scanners. Your system host adapter doesn't have to operate in target mode. Target mode lets your system look like a peripheral to another system so that the other host adapter can then address your system as a target. In many scanners a SCSI controller in the scanner acts as a processor target. It then looks just like a SCSI peripheral to your system, and it basically only supports two commands - send and receive. This may be a host adapter plugged into an embedded PC in top end systems or an embedded NCR controller chip in cheaper ones. On an embedded PC the adapter must operate in target mode, and the reason we happen to have target mode in the 1542 driver is I added it to serve as an embedded controller. The trick for a SCSI processor type scanner is to figure out what to PUT in those send and receive blocks. They are a transport layer for a proprietary protocol that may or may not be documented. In addition to processor type scanners, I believe AGFA actually implements the SCSI scanner protocol you'll find in the SCSI-II spec, while other scanners are just totally non-standard SCSI devices. For the scanners I've used: HP, Optronics: Processor type devices with embedded protocols in the data streams. Canon, Microtek: Custom protocols. > This is why many of them come with their own custom AIC6360 based > cards. They come with their own cards because they don't expect PCs to support SCSI. Note that they don't have their own cards for Macs. > If you happen to have a good controller (as opposed to one that > works for HD's, etc.), then you can implement the scanner software > on top of it. Any of our drivers will drive a scanner that is well behaved on the SCSI bus and that we can get the documentation for. The "well behaved" warning is that the firmware on these low end plotters may not be well behaved on a real computer. A good example is the Microtek ScanMaker II that will not disconnect from the SCSI bus while physically positioning the scan head - not a good neighbor. -- Peter Dufault Real Time Machine Control and Simulation HD Associates, Inc. Voice: 508 433 6936 dufault@hda.com Fax: 508 433 5267
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