Multiscan demo programming

[larsef]

First of all, I wonder if there exists a multiscan (VGA/AGA) demo for the A1200/A4000? I have been looking for demos to my A1200 but I have only found PAL or NTSC demos, not multiscan demos. I'm interested in this because I only have a SVGA-screen and can only look at PAL/NTSC demos through a VGA-TV box which gives really crap quality. It would be interesting to see what can be done in multiscan mode. I realize multiscan mode slows things down, but I do get high resolution instead.

I have been thinking about programming a multiscan demo myself. My thought is to open a multiscan screen in a system friendly way and take over from there. The question is, how do I take it over? I want to use raster interrupts to make things smooth and I want to get direct access to the screen. I don't want to access the screen in a system friendly way, because that would only slow things down.

Any thoughts/suggestions?

[Karlos]

You could just get a graphics card and kick the crap out of the framebuffer ;-)

Seriously though, VGA modes really do suck up chip ram bandwidth. They are good for showing static images and what not but I'm not sure you could realistically accomplish from a demo perspective.

[skurk]

Here's one you can start with: clicky

Written by Fabio "Maverick" Bizzetti.

[darkcoder]

There are more limitations in Multisync modes. Anyway, I did a small multisync demo, back in 1996! :-)
It's really a technical proof-of-concept rather than an artistic effort, but it's definetly Multisync.
My effort was not only to make it work at different scanrate, but to allow the user to switch video mode at run-time.

You can find it on aminet, demo/euro/BeamCtrl.lha

Let me know if you like it!