| From: | r.m.leith |
| Date: | 26 Sep 2001 at 20:46:47 |
| Subject: | [amigactive] Re: SCSI question |
--- In amigactive@y..., Steve Hargreaves <Steve@h...> wrote:
> Hi there,
>
> I have a squirrelscsi interface. At the moment, the only device on
> the chain is a CD, but I'll be adding a HD in the next week or so.
>
> If I connect the CD(internally) using a centronics convertor (with
> a 2nd centronics I/F hanging of it, I have no problems.
>
> If I use a convertor to convert the squirrel to and internal scsi
> I/F, and then connect the CR with an internal cable to that (with a
> 2nd internal I/F hanging off it), the drive isn't recognised.
>
> Is this a termination problem, and should it go away when I connect
> the HD to the branch?
>
> All the best
>
>
>
> Steve
Steve,
If the internal and external 'convertors' are what I think they are,
they constitute a simple metalic connection from scsi interface to
the connector pins. The result should be the same whether you connect
internally via a ribbon cable or externally via a Centronics cable.
However, I am not sure how you have the choice. Do you have a
standalone SCSI CD case and power supply which enables Centronics
connectors?
Whatever, I have had few problems with internally and externally
connected CDROMS even when incorrectly terminated so don't assume
that termination is necessarily the problem. The fact that you get
different results depending on the type of connection suggests that
the internal cable connection is at fault. If you have made it up,
yourself, you might just check that the pin 1. connection from the
Squirrel interface is correctly connected to pin 1 on the CD drive
(usually, the end of the scsi connector nearest the power connector}.
It is possible to clamp the IDC connector the wrong way around thus
putting a 'twist' in the connections.
Also, I have recently had problems with a new SCSI CDROM, but not on
the Amiga. The latest drives have a jumper-connected, automatic
terminator feature thus eliminating the need for ribbon cable
connected terminators. My drive refused to be recognised when this
termination was enabled even though there were no other terminating
devices in the chain. Moving the jumper to the disabled position got
the drive working and it has been fine connected to a range of
devices including an audio sampler and a PeeCee. I still think you
should have the same results with either mechanical connection
arrangement so only experiment with termination when
you are sure the cable connections are straight.
Regards
Roy Leith
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