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Forums > C64 Coding > Forcing Hires when in multicolor through d011?
2018-06-30 08:02
Oswald

Registered: Apr 2002
Posts: 4314
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.
2018-06-30 08:10
JackAsser

Registered: Jun 2002
Posts: 1472
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?
2018-06-30 12:15
Oswald

Registered: Apr 2002
Posts: 4314
I cant set ecm, when the only change is setting d012 (irq pos) +-1 ? :)
2018-06-30 12:18
Oswald

Registered: Apr 2002
Posts: 4314
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 ?
2018-06-30 12:30
ChristopherJam

Registered: Aug 2004
Posts: 867
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?
2018-06-30 13:28
soci

Registered: Sep 2003
Posts: 410
Illegal mode is hiding stuff by using black on black but you can put sprites in between to reveal what's there.
2018-06-30 19:43
Oswald

Registered: Apr 2002
Posts: 4314
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.
2018-06-30 19:46
Oswald

Registered: Apr 2002
Posts: 4314
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 :)
2018-06-30 21:34
TWW

Registered: Jul 2009
Posts: 444
Wasn't that reading RAM inder $00/$01 IO?
2018-07-01 02:22
Oswald

Registered: Apr 2002
Posts: 4314
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.
2018-07-02 20:56
Digger

Registered: Mar 2005
Posts: 295
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).
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