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Old March 9th 06, 06:54 PM posted to alt.comp.periphs.hdd,comp.sys.ibm.pc.hardware.storage,microsoft.public.win98.disks.general
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Default Can IDE cable's end connector be left idle ( w-o affecting data transfer ) ?

"glee" wrote in message
...
You are correct as far as what that particular web page refers to: 40-pin,
80-wire IDE cables.


Correction/Typo: That should read: 40-pin, 40-wire IDE cables. Brain
failure (again)!

I'm not sure I should go so far as to say you are correct there, either.....
there can and will be the possibility of "electrical disturbances"
regardless.

....glen

It is my understanding however (and the recommendation of the
manufacturers), that 40-pin, 80-wire IDE cables *do* require particular
devices to be attached to particular connectors on those cables, and that
the end connector *not* be left vacant. This is especially true in the
example given in the original post: using Cable Select.

http://www.pcguide.com/ref/hdd/if/ide/conf_Cable80.htm
--
Glen Ventura, MS MVP Shell/User, A+

"Arno Wagner" wrote in message
...
In comp.sys.ibm.pc.hardware.storage TE Cheah wrote:
Per www.pcguide.com/ref/hdd/if/ide/confCable-c.html
"Using the middle connector and leaving the end connector unattached
..... leaves part of the cable "dangling". This is called a stub and

creates
much worse electrical characteristics on the cable, due to reflections
from the unterminated ends of the cable wires. It is not recommended."


I 1st ignored this warning, & found my Toshiba cd drive ( using cable
select, & assigned by Award bios as 2nd channel's slave device )
though can play any VCD just as well, cannot pass BCM diagnostic (
blue screen of "fatal error" appears in Win98se ) unless I use the end
connector of this 80 wire cable to connect this drive ( i.e. bios
assigned as master device ) to my ( VIA ) kt266a 's hdd controller.


Does any1 here have a similar experience ? If this warning is valid,
then why does no mboard / hdd / cdd / dvd / cable manufacturer warn
users of this requirement ?


First, IDE cables are not terminated. That means that for the drive on
the middle connector it makes no difference whether there is a drive
at the end or not! If anybody says different, then they do not
understand the subject matter. In SCSI cables (what likley causes
the confusion) it is a different matter: The last device on an
SCSI bus _is_ terminated and havinf no device there either means the
bus is not terminated or it is teminated somewhere in the middle.
Both useually cause mor or less secvere problems. Again, the same is
_not_ true for IDE cables. The device at the end does _nothing_ for
signal quality when the controller and the device in the middle
talk to each other. From the point of view of the device in the
middle, the end-connector is allways empty. The only exception is
during the power-on sequence, but not during normal operation.

That said, yes, the electical characteristics are worse, but any
well-designed IDE device needs to be able to deal with it. I do have a
TEAC CD-writer (CD-W540E) that is sensitive to rounded cables when
data is transferred to the device. I get bit-errors on the written
CDs. The burner has no problems with normal flat cables, no matter
what connector it is on. I would say the device is borderline broken
by design. If you use standard length flat cables then the CD drive
or IDE controller has likely been damaged, e.g. by static electricity.
It usually makes digital I/Os much more sensitive to noise.

Arno