[rescue] SS20 screen not found

[Romain Dolbeau]

Le mer. 29 oct. 2025 à 14:26, Ethan Hawke via rescue
<rescue at sunhelp.org> a écrit :
> > The main thing
> > I'd need is some specification of how the module is supposed to
> > identify itself and provide the included logo image and such,

Either the host PROM or the device PROM will contain the required
fcode (Forth for OpenBoot) to initialize the device so it's usable as
a console.
I have not looked at the cg14, but for the cg3 or TGX the PROM are
floating around (for e.g. 'tme'), it's not very complicated, just
setting up the clocks and DAC and some basic functions (display
characters, things like that). The TGX one also has some acceleration
for scrolling, but the (T)GX have quite a bit of documentation
available.
It's not particularly difficult to recreate a 'simple' device like the
cg3 or cg6 (only a single 8-bits plane, no fancy multi-planes like
e.g. the cg4) except for the acceleration, my emulated cg6 only had
the bare minimum for modern NetBSD (blitting, essentially).
24-bits is not very hard (actually 24-bits direct color is easier than
8-bits indexed, not CLUT!) but slow.

> > I'm thinking a better move for now would be to replace it with an SBus
> > framebuffer card

If you can live with 8-bits, then a TGX+ (which can do 1280x1024 with
no hassle, easier on LCDs than 1152x900) is your best option.
There are third-party 24-bits SBus devices, but they are a lot more
exotic and less well supported/documented than the TGX+...
Or you could roll your own, but let me tell you it can get expensive
and time-consuming :-)

> I am not aware of any detailed (programming) documentation for the
> cgfourteen system, just the brief datasheets.

NetBSD has quite a bit of acceleration with the cg14, so there's some
examples there, but it's not comprehensive.

Cordially,

-- 
Romain Dolbeau