> > I think whats needed is a ddc capable adapter box separate from the
> > card is better. that box can have headers or whatever switching
> > arrangement is necessary to tell the card what the preferred mode is.
> > that way whatever fixed mode hardware is "standardised".
>
> Actuallty, that's an excellent idea. Why couldn't we deal with
> fixed-frequency monitors by having a DDC box that taps the appopriate
> signals from the video connector?
This idea sounds very promising. There are a variety of possible uses.
(a) Telling a OGC / OGD card what video mode to use.
(b) Testing a OGC / OGD card's response to various DDC requested
modes, without needing a truckload of monitors.
(c) Telling some other (ATI/Nvidia/...) chip what video mode to use.
(d) ???
For (c) it would be useful to add a small circuit to allow converting
RGBHV sync to composite sync or sync-on-green. IIRC google can find
this.
We still have the question of how to set the mode of the DDC box.
(1) jumper or switches
(2) RS-232 port
(3) ???
For use with (b) the RS-232 option would allow automating the test.
Actually, you could automate it with jumper pins, but it would be a hassle.
It would be useful to have some circuit/chip that detects if the mode
actually generated matches the mode requested. If it doesn't match,
disconnect the video output to protect the monitor. Hopefully we can
trust the OGC/OGD boards, but if the DDC box is used with some other
graphics chip, and the mainboard firmware requests 640x480 but the
DDC box says use 1200x1024, which will the chip generate?
Some monitors have this sort of protection builtin, but others do not.
I don't know what sort of circuit/chip they use to do this, or if it
would be suitable for this DDC box.
This would also be useful for automating the test of the OGC/OGD cards.
Otherwise someone gets to go blind staring at an oscilloscope screen.
> IIRC, DDC supplies its own power,
> because it's supposed to work even when the monitor is powered off.
Why does DDC need to work if the monitor is powered off?
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