Re: CG14 and 16bit colour

[Michael <macallan1888%gmail.com@localhost>]

Hello,

On Tue, 23 Apr 2024 08:45:46 -0500
Andrew Ball <asbatwrk%gmail.com@localhost> wrote:

> Hello Michael,
> 
>   MM> I did a lot of work on the cgfourteen, sx and xf86-video-suncg14
>     > drivers, one thing I didn't expect was people asking for 8bit
>     > acceleration in X, mostly because with a 4MB cg14 you're limited
>     > to 1152x900 in 24bit colour, in 8bit you could go all the way to
>     > 1920x1200. So I wrote code for that.  
> 
>     Thanks for your work on this.  Out of interest, can they be made
> to send 1152x864 or 1920x1080?  Does the driver (or X11) have any
> concept of 8-bit greyscale?

From the driver's point of view 8bit greyscale is just 8bit with a
certain colour map. Also, cg14 is pretty much freely programmable when
it comes to video modes. I've seen OF scripts to make it do 1920x1080.

>   MM> Looking at the headers files, it looks like at least the DAC
>     > supports 16bit colour as well, which would allow 1600x1200 in
>     > more than 8bit colour.  
> 
>     I can see that being nice for 100 DPI on a 20" (visible diagonal)
> 4:3 screen.  I seem to remember that X11 shipped with 100 DPI bitmap
> fonts.

That, and scalable fonts. Most TFTs these days are bigger than
1152x900, native resolution just looks better than scaled.

have fun
Michael