RL_Dane, (edited ) 
Hey #Amiga folks,
In my little exploration, I'm re-creating the A500 I would've gotten in Christmas 1989 rather than the Macintosh SE I actually got.
My understanding is that the original A500 is capable of displaying 640x400 (NTSC -- I'm in the US) with 4 bitplanes...
So why does workbench display 640x200? (At least, that's what it looks like to me based on the non-square pixels I'm seeing in font rendering)
Update: to avoid interlacing. I forgot abt that 😅
Many thanks for the explanations!