with apologies to Aerosmith
I used to use a DEC VR290-DA VAXstation monitor with my Linux box. It's a typical fixed-frequency monitor with sync on green.
SVGATextMode and XFree86 supplied the required video signals.
The only hardware I used was a trivial sync adapter. It was a cheap trick; it added AC-coupled negative sync pulses to the green video signal. This shifted the raster up a little bit, making the green signal slightly brighter than the others, but I usually couldn't tell.
VGA R o--------------------------o R BNC G o---------------------+----o G+S | B o--------------------------o B 220ohm +68µF | H o------/\/\-----||----+ 220ohm +68µF | V o------/\/\-----||----+
I connected the ground returns appropriately, of course; they're not shown. The pinout for the VGA connector is in the FAQ.
The only hard part about building this circuit was soldering wires onto the DB15 connector; if you can avoid it, do. Use a DB9 connector and an adapter, or get the end of a DB15 cable and break out the wires.
Now, don't go doing this with your fancy, expensive fixed-frequency monitor. My victim was free; I paid for it by carrying it home. For all I know, this particular monitor had unusually forgiving sync amplifiers or something. My technique may not work for any other monitor.
I didn't have an oscilloscope handy to look at the waveforms, so I can't tell you how ugly they were. Probably butt-ugly. But it worked for me.
The only problem I had configuring XFree86 was finding the right sync width and blanking interval timings. In fact, I didn't find any. I just tried the timings for a nearby VESA mode, cribbed from a modeline that came with XFree86, and they worked. Let me know how these numbers work for your VR290.
Here's the Monitor section from my old XF86Config:
Section "Monitor" Identifier "Primary Monitor" VendorName "Digital Equipment Corporation" ModelName "VR290" HorizSync 53-55 # 54kHz VertRefresh 59-61 # 60Hz # # scan rate: 54khz (found specs on the Web) # refresh rate: 60Hz # h-back-porch: 320ns (cribbed from 1024x768@70Hz) # h-sync-width: 1.81us # v-back-porch: 53.1us # v-sync-width: 106us # sync-polarity: - (what my cable needs) # # (insert (modeline 1152 864 80.59e6 54e3 60 320e-9 1.81e-6 53.1e-6 106e-6)) Modeline "1152" 80.590000 1152 1176 1320 1496 864 866 871 900 -hsync -vsync EndSection
I derived my TextConfig modelines directly from my XF86Config modeline.
I had to boot blind, as this monitor doesn't support the usual PC video modes. Occasionally, I had to borrow my girlfriend's multisync monitor to fix massive lossage. I ran SVGATextMode as early as possible, which let me watch most of the boot sequence and, of course, log in on the console.
I ran XDM at one time, but every software upgrade seemed to break it, so I punted it in favor of SVGATextMode alone. I don't like XDM much anyway, because it makes it hard to run the server with custom options.