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MaPa

New Direction - 1k intro

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Hi, here is our latest production. 1k intro presented at Forever 14 -Elvis Lives party where it took 2nd place. Source code included as always. Enjoy.

 

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    New Direction
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1k intro for Forever 14 party

     code: MaPa
     msx: PG

contact: [email protected]
    [email protected]

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post-3960-0-52387100-1363545447_thumb.png post-3960-0-57567000-1363545452_thumb.png post-3960-0-91284600-1363545456_thumb.png post-3960-0-69737600-1363545460_thumb.png

 

New Direction.zip

Edited by MaPa
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Wow, awesome sideways color bars! What an awesome feat of cycle counting and precise timing. Love the three instruction display list. Way to go!

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Just wow! How did you cram so many colours in a scanline? I guess I will have to look at the source, but it still won't help me, I'm sure :)

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Awesome! nice trick with VSCROLL to avoid ANTIC screen-DMA access :]

Edited by seban

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So the record for colors in a line is something like 85 then? :)

I think there is up to 90 colors in a line (overscan).

 

How?

Easily ;) Simple GTIA mode 9 with midscanline background color changes with VSCROLL trick help to avoid screen DMA and allow more changes.

 

Just wow! How did you cram so many colours in a scanline? I guess I will have to look at the source, but it still won't help me, I'm sure :)

I wrote it just above.. and surely you would find it out from the sources too :)

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Nice. I'm about to sleep and will be left wondering (after having quick look in debugger) how the hell the thing works despite the Refresh cycles.

 

It would appear the horizontal bars move by a single pixel per frame - so I'm thinking now that a diagonal colour bar effect should be possible then.

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It would appear the horizontal bars move by a single pixel per frame - so I'm thinking now that a diagonal colour bar effect should be possible then.

 

Yea! Does HSCROL still work with the VSCROL no-DMA trick? If so, you could use HSCROL to shift bit pattern up to 8 16-color pixel widths each line and change the COLBK kernel each line to make the pattern diagonal.

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VSCROLL trick - disable badlines - DMA at first row

 

 

G2F -> Special -> Disable badlines

 

Mode -> GED+ -> Save ASM

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HScrolling is still OK with the VScrol line extender trick although with HScrolling you lose more cycles per scanline as there is more graphics DMA.

In GTIA modes HScrolling is only valid in 2 colour clock chunks due to how the pixel data is combined.

 

My first impression was that it was a PMG overlay trick but of course we don't have the speed for that. I'm going to have to single-step this, I really never thought the CPU would be fast enough for so many colour changes.

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HScrolling is still OK with the VScrol line extender trick although with HScrolling you lose more cycles per scanline as there is more graphics DMA.

 

You lose 8 cycles per "mode" line when enabling HScrol. Only at first scanline of line extended with VScrol, the remaining scanlines are without any DMA (only stupid RAM refreshes in display area). In case of this intro there already is wide screen so HScrol does not make it any worse and it is used to scroll.

 

 

My first impression was that it was a PMG overlay trick but of course we don't have the speed for that.

 

AFAIK in GTIA mode 9, you can overlay the graphics only with 5th player. Normal players will not OR with background.

 

 

I'm going to have to single-step this, I really never thought the CPU would be fast enough for so many colour changes.

 

 

And as we have no DMA and all cycles are left to the CPU then 8 pixels wide bar equals to 8 CPU cysles, so LDA #imm, STA $abs with 6 cycles is fast enough. Only "problem" are 9 RAM refreshes in left part of the screen, where the 6 cycles of LDA/STA will hit two refreshes, lenghten it to 8 cycles.. exactly the size of the bar ;)

Edited by MaPa
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Great effect and lovely intro, so nice to see people still making the humble Atari sit up and fetch :)

Edited by Mclaneinc

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