🚀 go-pugleaf

Dave Olson writes
   In <CHIN.92Apr5104133@walnut.chem.upenn.edu> chin@walnut.chem.upenn.edu (Chin Wu)  
writes:
   | > You ALWAYS have to power ALL devices on a SCSI chain.  Sorry.  And
   | > you should remove all terminators, except for one at the end of the
   | > chain.  The physical order of the scsi devices makes NO difference
   | > in a properly installed and terminated chain, any evidence to the
   | > contrary points to something wrong.
   | 
   | I am not so sure this is correct. On my system, I have a external hard
   | drive and a CD-ROM drive. The hard drive is a fujitsu 660M and since
   | it is so loud, I won't turn it on until I need it. Same thing goes for
   | the CD-ROM drive.

I won't pretend to know the electrical stuff. But in practical terms, some devices won't  
be recognized if they are turned on AFTER the computer has booted, since the computer  
polls the SCSI bus to learn what devices are there only at bootup. Some drives obviously  
seem to actively signal the computer of their presence when they come on-line after  
bootup, but if so, I suspect this is is risky since other devices may be trying to use  
the bus at the same time.

Leaving a device off throughout the session should not be a problem -- unless it is the  
LAST device, which should be the ONLY one terminated. For reasons best explained by an  
EE, some of these terminators require power to operate correctly.

-- 
Robb Aley Allan, The Gulfstream Group
220 Sunrise Avenue, Palm Beach, FL 33480
voice: 407/ 832-4013   email: Robb_Allan@gun.com
Co-founder/director, Gotham Users of NeXT (GUN)