First post, by Andrew0Red
I've searched and searched, finding no good solutions, so I'll post this one, even if it isn't perfect:
What I did: In Nvidia control panel:
1) Change resolution -> userdefined -> create one of 1280x600 (i.e. a 2.1333 ratio)
2) Adjust desk size and placement -> Full screen (as opposed to conserve-aspect-ratio or no-stretch)
In dosbox.conf:
1) Fullresolution = 1280x600
Scaler = normalx3
And - voila! - I now have 320x200 pixels, taking up a 4:3 portion of the screen!
Technical notes: Nvidia card, and it already had resolutions of 1280x??? and ???x600, so I knew both should work.
Hope this helps someone out there!
- Andrew Red