Re: How is graphics rendered in various older computing devices supported by NetBSD

[Martin Husemann <martin%duskware.de@localhost>]

On Tue, Oct 01, 2019 at 03:35:42AM +0530, Arvind Arvind Pro wrote:
> Or is the graphics/text rendered based on the type of graphics
> adapter- eg SVGA(Super Video Graphics Adapter) / EGA(Extended Graphics
> Adapter) and so on? If someone can shed more light on this it would be
> very helpful.

Heh, those are pretty modern graphic cards ;-)

Indeed the rendering depends on the framebuffer device and is done
differently in various drivers. Many of the old graphics adpaters have
hardware acceleartion (e.g. for scrolling) and the framebuffer driver
makes use of that. A classic example is the cg6 device used on old
sun machines, see:

	https://man.netbsd.org/cgi-bin/man-cgi?cgsix+.sparc+NetBSD-current

Most (all?) of these drivers use a common library called "rasops", see

	https://man.netbsd.org/cgi-bin/man-cgi?rasops+.sparc+NetBSD-current

and attach a "wsdisplay" console device:

	https://man.netbsd.org/cgi-bin/man-cgi?wsdisplay+.sparc+NetBSD-current

You can find the various drivers by doing a "full search" on nxr for rasops:

	https://nxr.netbsd.org/s?n=25&start=0&q=rasops&sort=relevancy&project=src

Does that answer your question?

Martin