Hello, * On Fri, Jan 29, 2016 at 11:09:24AM +0100 silverdr@wfmh.org.pl wrote: > Open ended (and possibly also unshielded) wires never do any good to signal > quality. They are nice antennas, which will add whatever electromagnetic smog > flies around you to the signal but will also try to radiate your signal out. > None of these helps. Termination - the drive should provide it, similar to what > was a standard in SCSI devices. Still, I wouldn't bet all of them do. I > wouldn't be surprised if some were cost reduced because it still worked in > basic cases. How to make own? Either check the older, still standard compliant > implementations or maybe checking the original SCSI devices? I just did a web search and found the following: http://www.scio.k12.or.us/shs/staffweb/mettsg/comptec/SCSI/Scsi_termination_tutorial.htm Passive termination is a resistor network, 330 ohms from ground to the signal line and 220 ohms from the signal line to termpower, which is an equivalent impedance of around 132 ohms. Since typical characteristic impedance of most cable is between 85 and 110 ohms, this is not a great match. I remember two resistor packs on my SCSI drives, but I always thought this was because there were more signal lines than they could be handled by one resistor pack. Can anyone confirm that SCSI used two resistor packs, one to ground and one to Vcc, with different resistants? Regards, Spiro. -- Spiro R. Trikaliotis http://www.trikaliotis.net/ Message was sent through the cbm-hackers mailing listReceived on 2016-01-29 21:00:10
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