How do different resolutions (pixel sizes) work? I get that everything memory related (including color mode and depth) could be switched on a raster line.
In theory it should be possible to change the frequency of the video signal mid screen as well, but I have a hard time to imagine switching repeatedly every frame wouldn't have driven the monitors of the time crazy. Even multi-sync monitors needed probably a couple of frames to sync, right?
It’s basically just an SD TV signal, the vertical height in lines doesn’t change, it largely just swaps if each line outputs 320 or 640 pixels during its assigned time period.
Having interlaced and non interlaced modes at once seems a bit funky though, but I assume it just forces everything into interlaced with the non interlaced mode sections having the same line sent on both fields?
AmigaOS does indeed enable the extra half line when any visible viewports are interlaced. Fortunately that just works because the individual “non-interlaced” fields are still legible when shifted back and forth by a half line.
Forgot to add this earlier. Later versions of AmigaOS that support non-15kHz rates will promote all screens to the lowest screen mode that can suppprt all visible screen resolutions. So, if you drag a NTSC:High Res Interlaced (640x400@60i) screen down in front of a Multiscan:Productivity (640x400@70p) screen, then the front screen will also display in Prpductivity mode.
weinzierl · · focus · HN ↗
In theory it should be possible to change the frequency of the video signal mid screen as well, but I have a hard time to imagine switching repeatedly every frame wouldn't have driven the monitors of the time crazy. Even multi-sync monitors needed probably a couple of frames to sync, right?
fredoralive · · focus · HN ↗
Having interlaced and non interlaced modes at once seems a bit funky though, but I assume it just forces everything into interlaced with the non interlaced mode sections having the same line sent on both fields?
LocalH · · focus · HN ↗
LocalH · · focus · HN ↗