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Comment by 9rx | Hacker News Reader

> To be blunt, the term "DB9" is plainly inaccurate because it pairs the 25-pin "B" shell with a 9-pin count, a physical contradiction.

Why couldn't a DB shell house a 9 pin connector? I don't see the physical contradiction (even if nobody actually manufactures such a thing).

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It can, but nobody would do that as it would be cheaper to use a DB-25 connector and not use all the pins. If they went for the cursed true DB-9 they would need to meet the minimum order quantity for a special order, pay for the manufacturer's tooling, and any required certifications. If you needed the spacing between pins for some reason you would probably just specify the use of crimp-and-insert.

That being said, the DE-0 is real, but it can't hurt you.

> That being said, the DE-0 is real, but it can't hurt you.

That depends on several factors, like its current velocity.

While your statement is perfectly accurate, I just wanted to blithely add that it's not the velocity that hurts you, it's the change in velocity :))

While it's a common joke, not quite - if you're hit by baseball, your velocity does not change significantly as energy is dissipated in other ways, and the change in velocity of the baseball is a consequence of the lost energy, not a cause of damage.

Dissipation of energy hurts you. :)

Velocity alone can also kill: https://what-if.xkcd.com/1/

Randall Munroe rules this space IMHO.

Doesn't VGA use DE-15?

Edit: I was wrong, it is DE-15 connector. They squeeze 15 smaller pins into 9 pin housing.

You can remove pins from D-sub connectors. There are dedicated tools made for doing so.

In a pinch, a pair of pliers works too.

Searching google for DE-0 didn't bring any results but now I am curious to see it.

https://uk.rs-online.com/web/p/d-sub-connectors/0481049 https://uk.rs-online.com/web/p/d-sub-connectors/2748593

Isn’t that just a normal bring-your-own-contacts connector housing?

Yep. Though if you don't place any of them - depending on how technical you want to get - that's a DE0.

It's just a filler that in the form of a DE connector with no holes for any pins. It was an old full-rack CISC AS/400 for what it's worth, but I scrapped it 30 years ago.

I have a vague memory of a computer (probably in the 16 bit era?) saving money on providing two joystick ports by using a DB25 housing with the middle pins removed, leaving two 9 pin clusters at the ends, into which two DE9 joysticks could be plugged. The case plastic covered over the middle of the connector.

It was an accessory to let you use Amiga joysticks on the PC, from the mid 90s. I had one.

Could well have been, though I’m still picturing a computer in my mind. Wasn’t the SAM Coupe, but that’s the sort of thing I’m recalling.

But: it was probably quite common on joystick interfaces, now you mention it. Thinking along those lines and searching for ‘twin joystick adapter’ let me actually find an example: https://www.ebay.com/itm/276075015721

Worth noting that in the image that shows two joysticks plugged in they really don’t look like they fit all that well…

yeah it was basically that but I don't remember if it had USB or if it still had the old 15 pin analog at the other end.

I’ve seen (many… many years ago) a DB housing with 9 connectors but with the spacing of 25 pins. Would this then be a DB25C9P?

In retrospect, I think this may have been an adapter from DE9 to DB25, but it would have been a quick way to save a few pennies when only 9 pins were used for serial communication.

Another possibility is Sun or SGI 13W3 display connector. They were DB25 shaped connectors with 10 regular pins and 3 giant pins for video signals.

True. However, mine were for connecting to modems, so they were definitely only 9 pin serial cables. I didn't have the pleasure of seeing the 13W3 connectors until I was in grad school, and I still think they look weird. It didn't occur to me until today that they were the exact same size/shape as the DB connectors. They were so different that the thought never occurred to me!

Also the NeXT “Megapixel” displays. But note that none of these were compatible.

How would you even count those 3 giant pins? If I recall correctly, they were for coax cables that ran within the main cable. So each of those pins would have a contact for the shield and the conductor.

I’ve seen this also - I am unsure if it was a cost cutting measure or something else, but I’ve seen more than one connector with many missing pins.

The cables I saw were handmade. You can get connectors which are just the shield and an insulator with holes in the place of the pins. You crimp the pins onto the wires, then slide the pins into the insulator. You may have saved a few cents by not inserting the unconnected pins, but the reality is that most people left them out because there was no point in going to the trouble of putting them in.

It was pretty common for RS232 (-ish) DB25 connectors not to populate unused pins.

Sure you could do it. You could even put 25 pins in 9 pin housing if you made the pitch smaller.

They just don’t exist, and hopefully never will.

Sure you could do it. You could even put 25 pins in 9 pin housing if you made the pitch smaller.

They just don’t exist, and hopefully never will.

Maybe not as a standard, but I've seen a several companies stuff a crazy number of pins into a DE9 shell. I think one of them was my old GRiD Compass.

Beast of a machine. Heavy as hell, magnesium case, bubble memory, a screen that caused all televisions it was pointed at to lose their signal, and a sticker on the bottom saying it was illegal to use it in a whole list of countries, including Israel.

Seems like it has 19 pins in a DE9 shell. That's a lot. VGA connectors were also in a DE9 shell, but had 15 pins.

The funny thing about the GRiD DE9 connector is that it's labeled "Serial", but every DE9 serial port connector I've ever seen is 9-pin. I have to wonder what else they are cramming into that 20-pin DE9 "serial" port.

http://raster-burn.net/wordpress/wp-content/gallery/grid-113...

Heh flashback, I had an ati all in wonder, which was a video card with built in video capture. Now this involves a lot of ports so the model I had used a port breakout dongle for the video capture stuff, and some engineer had the bright idea to run all these pins through a mini-din connector. Think a ps/2 connector with about 10 pins crammed into it. Now ps/2 connectors are sort of stupid in the first place. why a round connector that is keyed to only go in one way? But this 10 pin variant was a nightmare to insert and by about the third time I made a firm resolution to never unplug it again if I could help it.

Footnote: keyed round connectors are not actually that bad, super strong, easy to seal and you can fit a large nut or bayonet clamp to them to make them extremely secure. However, this depends on having a well placed shell/key and mini-din doesn't, it is a bad connector. Not enough shell and key for solid locating so the pins tend to ride on the face while you try and orient it.

I think this was the one I had.

https://www.techpowerup.com/gpu-specs/all-in-wonder-9600.c86...

Whoa, I had that card (or one very much like it). I remember that cursed not-PS2 port especially.

VGA connectors were a DE-9 shell with 15 pins in them, and were used widely for many years to connect monitors to computers. There are other connectors that crammed 19 pins into a DE-9 shell. 25 might be a bit too much, but 19 is pretty close.

They're just DE shells, not DE-9

What's the physical contradiction, then? I don't get it.

The physical contradiction is that the standard requires a particular pitch of the pins, and a specific distance of the pins from the shell.

What's the point of "9", then? And how do you explain DE15 (popularized by VGA)?

> What's the point of "9", then?

Originally? Because that was the naming convention that Cannon designated. Later, because the shell size wasn't sufficient to determine the number of pins.

> And how do you explain DE15 (popularized by VGA)?

Cannon's D-series connectors started with 2 rows, at the "normal density" of 326/3000 of an inch between pins. They later expanded the range of connectors with "high density" and "double density" connectors that put more pins at greater densities into the original shell sizes. DE15 is in the "high density" range.

In a world with 3D printers, everything can potentially exist.

So if I put USB type C into a DB shell should I call it a DB-USB-C?

Yes, of course. You should be able to fit more than one in there, with a hub in the connector housing!

Man-made horrors etc.

"DB" already means 25 pins, so well, it's quite hard to both have 25 and 9 pins at the same time.

That is still pedantically different from a DB-25 of which we ripped out pins until it had only nine. The result would be "a DB-9" in big quotes, as it would't be "a", but more like "3/4 of a DB-25".

> "DB" already means 25 pins, so well, it's quite hard to both have 25 and 9 pins at the same time.

No, it doesn't. All of the D-Subs are readily available in high density versions:

  DA-15 | DA-26
  DB-25 | DB-44
  DC-37 | DC-62
  DD-50 | DD-78
  DE-9 | DE-15

The high density versions are commonly used in aerospace applications. Garmin is pretty fond of them.

There are also double density connectors putting 52 pins in a DB housing and whopping 100 connectors in the DD housing.

Also DE-15 is the standard connector used for VGA.

There’s also a now-quite-rare 23pin variant, which was used for the Amiga video port. Those connectors are getting harder to find these days, some people have resorted to modifying 25pin connectors when making Amiga video cables

DE-15 is none other than VGA.

DB housing can fit 25 pins in 2 rows. But it can also fit 9 really honkin big pins in 1 row, with a custom mold & pins. 3x groups of 3x12-gauge pins for 60A 3-phase delta power connector in a DB sized shell would probably work for a while before you burn your house down.

You mean this?

https://adamconn.com/product/8w8-connector

It's 8 pins, so, sorry, I'm not accepting it as DB9-of-doom. Maybe DB-8-of-doom.

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