Support for portrait screens in Plan 9 (e.g., on the bitsy)
has always depended on the underlying hardware being
able to present a portrait frame buffer, with the pixels
still in row-major order. That is, the "rotation" is done
in hardware, not software.
Some video cards support this; others do not.
To my knowledge, none of the current vga drivers
would provide access to such capability anyway,
but adding that (if you have helpful hardware and
know which register bit to flip) would be close to
trivial.
The easiest way to see what a gnot screen would have
been like is to boot a large monitor oriented in
landscape mode and then run
window 0 0 800 1024 rio
to get a gnot-sized sub-rio. Then pretend it's in black
and white and a lot slower.
Russ
