Re: [OT] SCSI Printer on AIC78XX without SCSI Terminator

[Brian O'Mahoney]

First, normal (non-differential) SCSI is an OpenCollector bus design
which simply wont work without a terminator and is designed to use
exactly two(2) terminators, one at each end of the bus, these both
provide a pull up and terminate the bus to prevent reflections. Also
the longer and faster the bus the more you depend on correct termination
e.g. 130 ohm - +3.3V

For much more detail, including external terminators please see

http://www.scsita.org/aboutscsi/SCSI_Termination_Tutorial.html

Second, there is usually a built in terminator in the AIC7xxx
adaptor, usually enabled in the SCSI BIOS.

Also check your device for negotiable SCSI options, eg SYNC, OFFSET

Gustavo Guillermo Pérez wrote:
> Hello, I was tried to use a SCSI Printer, onto a AIC78XX (old and new driver), 
> when driver load, it recognise the Scanner, the Printer and Panel, but may be 
> the copier doesn't have an internal terminator, and driver hangs forever 
> discovering unexistent 4th device. I do not wish to dissasemble the copier to 
> solder the terminator, and I never deal with SCSI HW. Kernel I was tried: 
> 2.6.7, 2.4.23. but I think the driver does not change from 2.6.7 to 2.6.12.
> 
> I see the doc about this driver but I can't figure out wich of a lot options 
> can help to not try to discover more than 3 devices... I'll have a chance to 
> play with this machine the next week, then I'm taking ideas.
> 
> aic7xxx=seltime:2
> this option wait for answer but the device 4º waits forever...
> aic7xxx=no_reset
> I don't....
> aic7xxx=override_term
> mmmmmm
> ...
> 
> The new driver support cmdline args?
> 
> If someone can share comment I would appreciate it
> 
> cheers

-- 
mit freundlichen Grüßen, Brian.

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