4 ms·

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

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.

bombcar 1y ago
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.
- II2II 1y ago
  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.
numpad0 1y ago
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.
- mbreese 1y ago
  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!
- II2II 1y ago
  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.
- teddyh 1y ago
  Also the NeXT “Megapixel” displays. But note that none of these were compatible.
kps 1y ago
It was pretty common for RS232 (-ish) DB25 connectors not to populate unused pins.

bombcar 1y ago

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.

II2II 1y ago
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.

numpad0 1y ago

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.

mbreese 1y ago
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!
II2II 1y ago
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.
teddyh 1y ago
Also the NeXT “Megapixel” displays. But note that none of these were compatible.

kps 1y ago

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