Posted By
Csabo
on 2016-11-15
02:16:59
|  Can we turn off the screen partially?...
Can we turn off the screen partially? This issue came up in 2009. While this can't be done with $FF06, it can be done with some trickery. Check out gerliczer's new technology demo called Screenoff (comes with full source).
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Posted By
Luca
on 2016-11-16
02:16:59
 | Re: Can we turn off the screen partially?...
Eureka! I tested it on the real machine: it works exactly as you can see on the major emulators! Didn't spent time to look into it yet, so I dunno how many shutoff areas can be achieved in one frame, but this means that one could easily save in great amount some of the rastertime in the areas he doesn't work into! To do an easy example, if you code a big plasma with some special features, stretching it below fullscreen would not simply "avoid too many calculations" but truly saving machine time!
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Posted By
Degauss
on 2016-11-16
03:19:12
| Re: Can we turn off the screen partially?...
I did this in Metamerism in the Twister and in the Tunnel-Part. I turned off the screen in the upper and lower third to get some extra cycles. My idea was to use $FF1D to "rewind" or "fast-forward" the screen-generation. Theres two things you have to take care of with this approach:
1) At the end of the screen $FF1D must have a "normal" value again, otherwise this will blow up the screen-generation
2) To turn on/off the border and to maintain a proper screen-signal, FF1D has to run accross or circumvent certain values. E.g. If you want to turn the display off, you could write $C8 to $ff1d in order to let TED think its the end of the visible area. Then again you have to roll FF1D back to some other value to NOT let come across the vblank area - otherwise TED would start to generate a TV-Signal again in the middle of the screen.
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Posted By
Chicken
on 2016-11-26
20:55:45
 | Re: Can we turn off the screen partially?...
Nicely done  This was partially (pun intended  ) discussed before in the various topics about max. screen resolutions and how to achieve them. For instance Crown's Magic Picture Show created three visible areas (if I recall correctly) and not one "big screen". Also back in the days of XeO3 development this was mentioned as a way to save some cycles.
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