Subject: Re: ncr hangs system
To: Ross Harvey <>
From: Matthew Jacob <>
List: port-alpha
Date: 03/18/1999 12:44:16
> SCSI-2 was never intended to be used in fast synch modes with external
> devices, and using two external scsi devices is venturing onto somewhat
> thin ice.  (Sure, people do it all the time, but people walk on thin ice
> and railroad tracks, too. :-)

Ross- I believe the predicate is wrong, but the conclusion is probably a
fair statement. Cable lengths and FAST-10 are fine for external devices
provided really good cabling (high impedance with minimal cable mixing)
and active termination. It's FAST-20 or higher which is really "no more
than 4 devices, very short bus length).

That said, the external connector on the Multia's NCR810 is *really* weak,
but I successfully run several external devices on it. What I have ended
up doing to minimize signal reflection problems is to remove the (useless
at 335MB) internal disk from the chain.