In <URL:news:local.netbsd.port-arm32> on Sat 07 Nov, Markus Baeurle wrote:
> Hi Kjetil!
> 
> In message <Marcel-1.46-1104213340-0b0+YEw@kjetilbt.eunet.no> you wrote:
> 
> > > (IIRC). It says that you should feed back HSync from pin 13 to pin 11
> > > (Monitor ID 0) to tell the computer to output CSync on the VSync line (pin
> > > 14). I did so and it works well for RISC OS, no difference to a connection
> > > on the D-Sub input.
> > 
> > This also tells RISC OS that your monitor is only able to use 15kHz modes.
> > At least that is what the TRM claims.
> 
> That's also in the welcome guide, but I don't think this is correct as I can
> use all my modes although I have made the link.

OK, that is good to know as I need that as well.

> > > How is the switching between separate and common sync done by the Risc PC?
> > > I would assume it's hardware but I`m not so sure because there is a bit in
> > > the VIDC control register to control this. (I only have a datasheet for
> > > the old VIDC but I don't think it was dropped in the VIDC20.)
> > 
> > I can check that if you like, as I have the VIDC20 data sheet.
> > I just asks ARM for it.
> 
> That would be great. I need to know which bit it is for the VIDC20.
> I'm pretty sure something has changed because the old VIDC only has two bits
> to set the number of bits per pixel so they must have extended these.
> The number of bits this is shifted in the RiscBSD source code tells me the
> same.

The bits to use are in the External Register at address C in hex.
The bits are:
19 and 18: syn-VS
	00 VSYNC
	01 nVSYNC
	10 CSYNCxnor
	11 nCSYNC
17 and 16: syn-HS
	00 HSYNC
	01 nHSYNC
	10 CSYNCnor
	11 nCSYNCnor

I hope this is what you need. If you need more information, I can
scan in the data sheet and mail it to you.

> > > I hope somebody can help me.
> > 
> > You could also buy or make a boks to generate composite sync directly
> > from the video output. I found a couple of these on the Net. At least
> > one of them are able to draw the power from the video port.
> 
> I tried that with the PC with disappointing results. The picture quality was
> quite bad with all kinds of distortion that even got worse with every access
> to the HD or CDROM! Maybe my mistake was to use an OR and not an XOR gate.
> Anyway, I find it much easier to hack the RiscBSD kernel as I'm compiling
> these myself anyway.

Did you make this yourself, or did you buy a high-quality one?

Kjetil B.
mailto:kjetil@thomassen.priv.no
http://home.eunet.no/~kjetilbt/