Re: tlug: Latest junk shop acquisitions

["Andrew S. Howell" <andy@example.com>]

>>>>> "Jonathan" == Jonathan Byrne <jpmag@example.com> writes:

    Jonathan> 2) It has a switch for setting the SCSI ID, which has a
    Jonathan> six-hole plug on the other end of its cable.  Presumably
    Jonathan> this is for attaching to the drive.  However, I don't
    Jonathan> have any SCSI drives that have a connection like that,
    Jonathan> but they do have jumpers for setting it. Is setting the
    Jonathan> SCSI ID on the drive and leaving the one on the box
    Jonathan> disconnected OK?

You could do it either way. By far the easiest is to just set the
jumpers on the drive, which is fine assuming that you don't need to
move it between boxes.

The six wire are three pairs, with one side being the ground on each;
on some cases they only supply on common wire, plus 1 wire for each
scsi id bit, 3 normally, 4 for wide. If you really wanted to, you
could cut the plug off and find connectors in Akihabara that would fit
the jumper pins. With a ohm meter and a bit of switch flicking, it
would be quite easy to figure out which pair was which bit of the scsi
id.

    Jonathan> 3) What about termination?

If the drive supports internal termination, you can set a jumper for
that. Otherwise, you should have a terminator on the last device in
your scsi chain. I would recommend using an external terminator, for
the simple reason that if later you add more devices, you don't have
to remember which one you have terminated. Having more that one drive
terminated can lead to strange problems.

Hope this helps,

	Andy
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