I have a 15 pin VGA monitor, but the computer I wanna use with it has a 14c VGA connection, and I can’t find any adapters, would it be possible to use?
Oh, and if it isn’t but you know there’s adapters, please send me links
Sounds like it’s always safe - the worst that will happen is the monitor won’t produce a picture.
Pin 9 is required by most, if not all, plasma and lcd TV’s to supply back to the computer graphics card information about the available resolution of the monitor. Pin 9 carries a 5 volt signal to the DDC (display data channel). New computer monitors (LCD or CRT) do not seem to need this pin, and work fine without it — as a result the majority of VGA cables labeled as “15 pin” really only have 14 pins, and this is never explained or noted in the packaging or product specifications!
Apparently, according to the link provided by @EdS, pin 9 is used as a back channel to the graphics card for the attached monitor to signal its native resolution. (Meaning, if it’s missing on the side of the computer, this signal would be of any use anyway, as there’s no notion of native resolutions in the design of the graphics adapter.)
There ARE adapters, I had one once for that very reason. May still have it, but it would be buried somewhere. The one I had was probably about one inch thick overall (that’s including the M & F connectors).
Early vga cards needed to “hear” from the monitor what resolution it wanted. Early Macs had to do this also, especially considering the fixed frequency nature of early color Macs.
The original VGA 15 pin connector had 4 pins (4, 11, 12 and 15) that the monitor or cable could either short to ground to leave open, allowing cards to distinguish between up to 15 different things that could be attached to it (only 4 combinations were actually defined). I had used the same idea in my older Merlin 2 computer but with 2 signals for 3 different options, and it worked ok.
Later on this scheme was replaced with an I²C interface (using pins 12 and 15) that connected to a small EEPROM chip inside the monitor. This chip could indicate the manufacturer, the model, available video modes and so on in a standard format.
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