[Tfug] SCSI cable adapter

[Bexley Hall]

Hi, John,

--- john galt <johngalt1 at uswest.net> wrote:

> From: "Bexley Hall" <bexley401 at yahoo.com>
>
> > <grrr> Why the hell can't things standardize on
> > *one* connector?  :<
> 
> You make me chuckle.

I shoulda gone into "stand-up"...  :>

> The topic of SCSI "standards" is far
> worse than the problem you are having.
>
http://www.ramelectronics.net/html/scsi_connecters.html
> 
> http://www.scsita.org/aboutscsi/Pictures.html
> 
> http://www.cablemakers.com/connector.html

Yup.  I have to contend with Centronics 50, DB25,
HD50, HD68, "old style Sun", 50 pin ribbon, SCA,
etc.  And, those *are* "standards"  :-(

> Then to complicate things... given some devices....
> you might have the cables to connect things but
oops,
> you are connecting to a RAID array which uses high
> voltage differential SCSI. Need different card in
> the host.

*And*, many devices fail to observe the proper
iconic labeling conventions so you can sort out
what they "expect"  :-/

> Then there's the whole Fiber SCSI / Channel thing...

If people *adhered* to standards "100%", things
wouldn't be too bad.  But, you can find a cable
that *looks* like it *should* work... *and*, you
can verify it has the proper pinning... *but*,
you later discover that the wires *within* the
cable haven't been arranged properly (e.g., the
standards specify where in the bundle the wires
should be located to minimize crosstalk, etc.).
And, you only realize that when you observe
flakey performance!  :<

> In a perfect world your PCMCIA adapter would have
> the cable terminating in a HD50M that it probably
> came with originally.

No.  The card terminates in a DB25M.  Perhaps it
originally came with a DB25->HD50 *adapter* but
I think it expected to plug into apple style
peripherals...

> (well, as Adaptec PCMCIA cards originally come
> with:  both LD50 and HD50 cables)
> 
> SCSI Host Bus Adapters, drives and peripherals
> *usually* have a female connector on them, IMO.

Yup.

> So in my view the PCMCIA adapter (with its
> proprietary connector on the card)
> and your female-femail adapter is oddball.

I think the card was designed with the thought
that they *had* to provide a pigtail of some
sort to connect to the PCMCIA card (since you
could never expect to plug *any* standard SCSI
cable into a card that small).  *So*, rather than
make a short pigtail that terminated in a
"traditional" connector -- onto which you would
then plug a standard M-M SCSI cable -- they probably
decided to fold the cable *into* the pigtail.
Problem is, they decided on the DB25 to support
instead of the HD50!  :<

> Hey, if everything connects and the cables are not
> too long, BE HAPPY.

<frown>  Extra connectors mean extra failure points
and impedance mismatches.  Consider how flimsy this
arrangement is to begin with and you can see how
adding more "widgets" just adds to the discomfort
level.  :<

--don


 
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