Most dual-monitor setups in the DOS era used Hercules ... and signal timing. The first VGA adapters would have 256kB of video RAM, 16 and 256-color palettes, and a maximum resolution of 800× ...

Old-school Macintosh-to-VGA ... working monitors around. Unless it’s a genuine Apple-approved CRT with the proprietary DA-15-based video connector, you are going to need at least an adapter ...