Subject: Re: pc164/ncr scsi problems
To: der Mouse <mouse@Rodents.Montreal.QC.CA>
From: Wilko Bulte <>
List: tech-kern
Date: 08/30/1999 09:26:25
As der Mouse wrote ...
> >>> For reference, this drive was working, synchronous, under SunOS
> >>> 4.1.4 in a Sparc LX (Fast SCSI, just not Ultra) at 10Mbit/s.
> >> Also for reference, my disks were working fine _for_years_ [...]
> > I hate to sound like a broken record, but 4 drives is really too many
> > for a singled-ended chain, especially if any of them are external.
> This is not my experience, unless you mean the comment to apply
> specifically to an alpha, or to that scsi card, or some such.
> I have a SS1+ at home - the machine I'm typing on right now, in fact -
> that I booted with six drives on, all external:
> - Micro-SCSI to DB50 cable (approx 1 metre).
> - Enclosure with two disk drives and a tape drive (approx .5 metre
>    internal ribbon cable).
> - DB50 to DB50 cable (approx 1 metre).
> - Two drives sitting loose on top of the enclosure, ribbon cable and
>    connectors from a dead enclosure, powered by a pc power supply
>    outside a case (approx .5 metre ribbon cable).
> - Custom cable, DB50 to DB25 - interestingly, many of the DB50 pins are
>    not present (presumably grounds).  This cable was made by giving the
>    cable shop a pasted-together assembly of adapters and cables and
>    telling them to build a single cable equivalent to it.  (Approx 2
>    metres of cable.)
> - SCSI-only zip drive.
> - Termination done with the switch on the zip drive.
> Worked fine.

This can be quite adequately be described as Pure Luck(tm). 
DB25-DB50 cables are an evil invention, as is mixing flat & round cabling
on the same bus (lesser evil than the DB25, but still a bad idea). 

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