It can be forth try unless we have to find other way to add a new
softswitch to support video mode for EGA and VGA. Apple II can't add new
softswitches unless we should be able to modify softswitch logic on the
motherboard.
You don't need to modify the motherboard.
The softswitches are in the vga card and only affect the video coming
out of the vga card.
I have read if I understand, but I want to give you my thought. They
claim to add incompatible video mode. Do you mean to add new softswitch for
VGA? If it is the issue, I would suggest to have 256 colors at 320x200
resolution. Total bytes are 64,000. You can divide it into 32,000. Main
memory will have 32,000 bytes and aux memory will have 32,000 bytes. Both
of them start at $2000 through $9D00...
Hmmm, we have to think carefully about this things.
Nowadays a common 17" LCD has 1280*1024 pixel, and this means 1.280
kilobytes @8bit screen depht... or 3 times as much for real color...
(did we mention color palletes yet ?)
Does an Apple II eat this ?