As far as I can tell from looking at the screen bitmaps in BeebEm it works but I haven't been able to test it properly. If someone could give it a go and provide feedback/a screenshot that would be great.
You'll need the VideoNuLA support ROM installed as well as this version of STEM. Then just CHAIN "T.VNULA" - this test/demonstration is not integrated with the menu.
Big list of known faults:
- There's some kind of incompatibility with the VideoNuLA support ROM VDU extensions, probably around claiming vectors. (I'm not saying this is the support ROM's fault, just that this incompatibility exists - I need to investigate, and may come back with questions later.) This is worked around in T.VNULA by enabling the extensions just long enough to select mode 101 then turning them off before enabling STEM - I am assuming the support ROM doesn't un-set the mode when the VDU extensions are turned off.
- It just assumes it's in one of the VideoNuLA 3bpp-bit attribute modes without checking. The output is wrong (but interestingly so) in mode 0 or 3, and the 2bpp-bit attribute modes will look even weirder.
- Double-width text almost certainly won't look right. The fact that there's a mandatory background pixel column at the right of each character means this is never going to look good in 3bpp-bit modes anyway, but right now it will just be terrible. (Reverse video, underlining and graphics characters will all inevitably suffer from this too.)
- I'm using Rich's "(M%ANDM%*2)*2" trick to modify the OS font bitmap to get a 5-pixel-wide font, so some characters (notably 'w') look terrible.
- It's dog slow - it's a debug build, and I've disabled the "fast path" which normally plots "simple" characters in an optimised way.
- Lots of other stuff I've probably forgotten.
That said, please share and enjoy!