3 ms·

On the Atari and Amiga, the horizontal/vertical scan rates are constant I can't speak to the Atari, but my memory is that this is not true of the Amiga. The A

On the Atari and Amiga, the horizontal/vertical scan rates are constant I can't speak to the Atari, but my memory is that this is not true of the Amiga. The Amiga could do this amazing thing where it would display multiple resolutions on a monitor at the same time, divided horizontally. Analog was flexible that way. An Amiga could even display two different resolutions from two different sources on the same monitor at the same time. This was part of my workflow when I used an Amiga to do live TV news graphics around 1990.

bitwize 4y ago
Yes, because the scan frequency didn't change -- that's what I'm trying to say (my terminology may have been a bit off). The timings of the horizontal and vertical sweep of the beam were constant; upon mode change the CRTC changed how scanout occurred, doubling the width or height of pixels in lower resolution mode but it didn't change the scan frequency, allowing the mode change to occur while the beam kept moving along. PC monitors were analog too, but with PC monitors from EGA onwards, changing modes meant potentially changing scan frequency, which required the monitor to sync with the signal at the new frequency. Apparently a high-quality Sony monitor could do this instantly but many of us were slumming it with monitors that took a while to sync.
- Moru 4y ago
  The Amiga could do a lot more than the Atari with the gfx chip. The Atari had three modes, 320x200, 640x200 and 640x400 so two horizontal and two vertical resolutions. It also can change frequency between 50 and 60 Hz but that wasn't instant, it took a couple of frames to stabilize. This I think you could use to get borderless screens with even higher resolution but I've forgotten exactly how it worked. For the highest resolution you needed a better monitor though so I didn't have much experience with that one. The Atari Falcon also had more resolutions with instant switch but my memory is getting quite fuzzy there :-)

bitwize 4y ago

Yes, because the scan frequency didn't change -- that's what I'm trying to say (my terminology may have been a bit off). The timings of the horizontal and vertical sweep of the beam were constant; upon mode change the CRTC changed how scanout occurred, doubling the width or height of pixels in lower resolution mode but it didn't change the scan frequency, allowing the mode change to occur while the beam kept moving along. PC monitors were analog too, but with PC monitors from EGA onwards, changing modes meant potentially changing scan frequency, which required the monitor to sync with the signal at the new frequency. Apparently a high-quality Sony monitor could do this instantly but many of us were slumming it with monitors that took a while to sync.

Moru 4y ago
The Amiga could do a lot more than the Atari with the gfx chip. The Atari had three modes, 320x200, 640x200 and 640x400 so two horizontal and two vertical resolutions. It also can change frequency between 50 and 60 Hz but that wasn't instant, it took a couple of frames to stabilize. This I think you could use to get borderless screens with even higher resolution but I've forgotten exactly how it worked. For the highest resolution you needed a better monitor though so I didn't have much experience with that one. The Atari Falcon also had more resolutions with instant switch but my memory is getting quite fuzzy there :-)