You're certainly correct in that publishing a bit of information in a particular
place doesn't make it fact. However, calling the small serial port connector
commonly seen on some DEC and all PC/AT equipment a DB9 is definitely wrong.
As always, it's easier to find nomenclature that's quite obviously wrong than it
is to find out what is right. However, it's a matter of finding out what is
right, not of inventing it, as folks in the business BlackBox is in are often
inclined to do, not only be cause they have to "do something ... even if it's
wrong" in order to give their product a name and description, but in order to
communicate to their customers what, more or less, it is they'd like to sell.
The fact that none of us seem to be able to make up our minds doesn't help a
thing.
The notion of naming sub-d connectors for the shape, shell size, and number of
pins certainly went down the toilet when they started packaging the same shell
with pins of differring position density. This notion was started by one
connector manufacturer and was resisted by a couple of their major competitors.
It did work much better than the 30-digit part number you'd have had to look up
from the catalog in order to specify completely any of their products. The fact
that we're still kicking this thing around after so many years is an indication
of how sticky a problem it really is.
Please see additional remarks embedded below
Dick
----- Original Message -----
From: "Tony Duell" <ard_at_p850ug1.demon.co.uk>
To: <classiccmp_at_classiccmp.org>
Sent: Monday, April 02, 2001 12:05 PM
Subject: Re: D connector tirade (was: Re: Age-old ethernet equipment)
> >
> > http://www.blackbox.nl/techweb/connect/db15hd.htm
> > it's a DB15HD, if you go to google and search, a heckuva lot of hits come
> > up for it. looking in a "Pocket PC-Ref" book I have also refers to it as
> > DB15HD. the D shell looks to be the same size as a DB-9
>
>
> I thought this whole thread started by somebody (IMHO correctly) pointing
> out that there was no such thing as a DB9 [1] and that the correct name
> for that connector is a DE9. The letter after the 'D' indicates the size
> of the connector shell.
>
Based on the notion I mentioned above, and the very example you pointed out,
there should, indeed have been just such a part descriptor. Under that scheme,
however, there could have been quite a number of other combinations that also
got the same moniker, even though the pin arrangement was quite different.
>
[1] Apart from the non-serious suggestion of mine that it should be used
> for a DB25-size connector with only pins 1-8 and 20 fitted. This
> connector was used on RS232 cables at one time. But I digress.
>
> So the 'correct' name for the VGA monitor connector can't be a DB
> _anything_. It must be a DE something. DE15HD or HDE15, or just plain
> DE15 would seem logical.
>
> Incidentally, because a name is commonly used by the PC-crowd, or because
> it's printed in PC 'hardware' books [2] doesn't make it correct. I can
> name a dozen things that are incorrectly named by such people (my
> favourite being 'going into the BIOS' when they mean the BIOS parameter
> table. The BIOS is a program in ROM).
>
> [2] I am not sure how anyone can write a hardware book without a single
> schematic or timing diagram, but the PC-crowd seem to manage it.
>
They have to write what their intended readers can understand. After all, lots
of people have made lifelong carreers of hooking up computer equipment without
ever concerning themselves with a schematic or logic diagram. Conflicting
practices made this difficult, but by staying with a single vendor, one could
eventually figure out what each connector at the bulkhead represented, e.g.
DB25S meant DTE, DB25P meant DCE, and so on, and do pretty well with that.
However, another vendor might have the convention differently implemented, i.e.
DB25S implies RS232, and if pin 20 is populated, it's DTE, etc. You get what I
mean (I hope).
>
-tony
>
>
Received on Mon Apr 02 2001 - 14:47:44 BST