At 7:59 AM +0100 2/12/02, Emile Schwarz wrote:
>Hi Marc,
>
>you=92ve got answers on the SCSI ID jumper but one miss:
>
>you cannot use two times the same SCSI ID; so before installing the 
>new Hard Disk drive, run SCSIProbe and not the used SCSI IDs;
>then you know the available IDs.
>
>
>Also, internal drives have internal "chips" set and external have 
>them removed (or was it the reverse ?) To be sure _and_ if you
>have a genuine external Hard Disk drive, look at its logic board for 
>those "chips"...
>
>
>What are those things I call "chips" ? Simple, but I do not know the 
>English name for that. Think it is internal "terminators".
>
>
>In fact calling the little SCSI block hardware "Terminator" is false 
>... this is an "impedence adaptator"... inside the piece of
>hardware, they are =93resistances=94.
>
>
>A little drawing of what I call "chips" above:
>
>   -------------
>   |           |
>   -------------
>   | | | | | | |  <-- this part is plugged in the Hard Disk drive logic boa=
rd.
>
>These were three of those in old Apple Hard Disk drives...
>
>Again, you may reach better explanation on Quantum www site.

Hi Emile,
SCSI has long used "termination", "terminator", and "terminating 
resistors" for the device used to dampen and stop reflection of the 
SCSI signal. Those "chips" which you diagrammed above are simple 
resistor packs as well. A SCSI chain is required to have two, and 
*exactly* two, terminations. One is built-into the controller, and 
the other must be supplied at the end of the chain.

Mike
-- 
Bikers don't *DO* taglines.