ECS and AGA could do non-interlaced 400 line scanning.
ECS could do non-interlaced 640x480 (+overscan) with 4 colors. In the documentation, 35 nanosecond pixels.
AGA same, but with 256 (or 262144 HAM) colors.
ECS could do non-interlaced 640x480 (+overscan) with 4 colors. In the documentation, 35 nanosecond pixels.
AGA same, but with 256 (or 262144 HAM) colors.
I think Commodore made one monitor that supported a bi-modal scan rate, and it was something like twice as expensive as the the regular Amiga monitor range. I also recall a somewhat exotic NEC 17" flat-face CRT monitor that was completely out of the question pricewise for almost anybody except institutions, that also could do it by virtue of having a continuously variable sync clock from 15 khz up to 45 or so.
The problem is not VGA 31 kHz modes, but old 15 kHz ones.
Most Amiga modes are 15 khz. The average person with an A500 or A1200 would have a 1084S and get zero value out of the new modes.