Re: SCSI question

[glyn@cs.ualberta.ca (Devin Reade)]

In article <5gmi37$27u4@uni.library.ucla.edu>,
 <pubpc1@library.ucla.edu> wrote:
>Also, how does one determine the correct orientation of an
>internal IDC-50 ribbon cable?  There are those that lack
>the orienting gromet (the stub that prevents plugging the
>cable upside down).

One edge of the ribbon cable should have a colour stripe on it.
This denotes wire #1.  There should also be an indented triangle,
groove, or other mark along the edge of the connector denoting pin
#1.  If the connector was correctly attached, these two will be on
the same side.  Sometimes the connector indentation has paint on it.

If pin #1 on the hard drive is not explicitly identified, you can
often identifiy it by looking at the PCB "pad" traces where the
connector is soldered to the PCB.  Most of the pads will be circular.
Pad #1 will usually be square.

Ensure the other end of your SCSI cable (and any intervening adapters/
connectors) are also properly aligned.

>What would happen if the drive
>mechanism was plugged in the wrong way?

You will likely fry one or more components in your system.  If I remember
correctly, reversing the lines connects all signal lines and the +V
rail to ground.

--
	Devin Reade	gdr@myrias.com