Well, I've learn some on vga drivers for Plan 9, and tried to run
my cute cube Pen4 box which include VIA P4M266 + VT8233
chipset sitting VGA chip in its northbridge.   The graphic chip's
id is 5333/8d04, where a short manual says it called ProSavage8.

I added a selection candidate for 0x8D03 after 0x8A25/26 in
all of vgas3.c, vgasavage.c under /sys/src/9/cp and virge.c
under /sys/src/cmd/aux/vga.
Yes, it boot 1600x1200x32 graphics,  however, I have 6.5 folded
rio windows horizontally.   I think it's correct in vertical direction.
Where I can touch the sources, because I have no tech manual
for this chip set.

the output of aux/vga -ip 1600x1200x32 is also included.

Kenji