Going blotchy means the scan drive got turned off.  You're just
watching the charge decay.

Geforce 2 Gos use the second CRTC and RAMDAC for the screen as the
silicon is specialised to drive flat panels.  This is what makes Gos
different from normal dual head nvidia chips.

Plan 9 programs CRTC/RAMDAC pair 1.If you connect a vdu to the
external VGA connector you will most probably see a picture.

You need all the hacks I did to make my Inspiron 4100 work.
Unfortunately, that's still 3rd edition. I don't have a date yet when
I shall be converting the laptop to 4th edition, and won't be doing
any hacks before then.

You are welcome to the aux/vga code as it was when I got the
4100 working. There is great similarity between it and the 4th
edition code, but you will not be able to escape having to understand
the nvidia driver, which is done by reading he Xfree86 4 source
as 'documentation'.