rasters4 by bitsnbites

screenshot added by marcus256 on 2014-08-07 11:22:25

platform :	Commodore 64 Commodore 64
type :	256b 256b
release date :	august 2014

popularity : 49%

49%

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alltime top: #33911

marcus256 [code]

added on the 2014-08-07 11:22:25 by marcus256

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My first C=64 release. It's awesome (and frustrating) to code the 6510 again! Unfortunately not tested on a real 64 (hope the filter sounds OK).

Pretty straight forward code here. Besides standard raster routine and sine table I squeezed in a "tune" and some variations.

added on the 2014-08-07 11:26:31 by marcus256

Great for a firstie! I tested it on some real hardware:

PAL C64G 8580 - timing bugs and white dots (thanks to the new VIC chip) in the sideborder, filters sound ok.

PAL C64C 6581 - timing bugs in the sideborder, filters sound ok.

NTSC C64 6581 - screen flickers, filters sound ok. Couldn't see any timing bugs, possibly because my NTSC TV doesn't show much of the border area.

If you set Vice to display full borders (or debug borders) in the Vic II settings menu, you'll see the timing bugs in the emulator as well.

rulez added on the 2014-08-07 15:19:41 by mermaid

@mermaid: Thanks for testing! I actually have a PAL breadbox, but no means for transferring the file from my Linux box. :-/ Will have to learn to do better raster timing then...

added on the 2014-08-07 16:03:25 by marcus256

You cannot have too much rasterbars in your life =)

However, here is a quick hack to push the "jitter" out of view:

Code:


        ;-----------------------------------------------------------------------
        ; Display raster bars
        ;-----------------------------------------------------------------------

        ; Main raster loop
        ldx #start_line

wait_line
        cpx $d012
        bne wait_line
	nop ; push jitter out of sight

next_line
        lda colors-start_line,x

	ldy #9
delay
	dey
        bne delay
	bit $ea

	sta $d020
        inx
        bne next_line

Will only work on PAL machines though.

For jitter-free, "stable" rasters I recommend reading up on the articles over at
codebase64.

added on the 2014-08-07 17:23:49 by ruk