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Oswald
Registered: Apr 2002
Posts: 5094 |
Forcing Hires when in multicolor through d011?
doing linecrunch...
when the timing is bad (d011 write is +-1 line off) the effect is suddenly in black and hires ?
while d016 = d8 and d800 all bytes are set to multicolor. |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
I’m sure u set ECM accidently and together with MC you get illegal mode hence black. Then you think the chars are in MC but they’re not? |
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Oswald
Registered: Apr 2002
Posts: 5094 |
I cant set ecm, when the only change is setting d012 (irq pos) +-1 ? :) |
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Oswald
Registered: Apr 2002
Posts: 5094 |
also ecm+multicol, then sprites are visible under illegal mode ? because I have sprites under char layer, and they are visible, so its not illegal mode I suppose ? |
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ChristopherJam
Registered: Aug 2004
Posts: 1409 |
More information? Like, is it displaying your bitmap data but just in the wrong mode, or is it some other repeating or nonrepeating garbage?
Also, what was d011 before the write, and what value are you writing? |
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soci
Registered: Sep 2003
Posts: 480 |
Illegal mode is hiding stuff by using black on black but you can put sprites in between to reveal what's there. |
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Oswald
Registered: Apr 2002
Posts: 5094 |
maybe its that I have ecm mode before linecrunch starts, so maybe it remains in ecm + multicolor illegal mode which looks like hires pixel? but iirc I have removed that ecm mode switch on and change into hires stayed. more tommorow. the effect in question will be shown at gubbdata now. |
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Oswald
Registered: Apr 2002
Posts: 5094 |
Quote: Illegal mode is hiding stuff by using black on black but you can put sprites in between to reveal what's there.
I thought thats not possible, because some article blabbled about reading out data with sprite-gfx collision using a sprite containing 1 pixel only. but then it can be "read" out much simpler :) |
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TWW
Registered: Jul 2009
Posts: 545 |
Wasn't that reading RAM inder $00/$01 IO? |
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Oswald
Registered: Apr 2002
Posts: 5094 |
clarence suggests that delaying linecrunch +-1 rline may stretch another char row, which contains d800 values that are hires even in multicolor. will test later. |
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Digger
Registered: Mar 2005
Posts: 437 |
Just read this https://spectrum.ieee.org/ns/pdfs/commodore64_mar1985.pdf which left me hopeful someone discovers a way to unlock the illegal mode and use it for multicolour ECM. Or at least something more than reading the screen pixels via sprite collisions (which is still very cool regardless). |
