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Demos Amiga Demoscene Archive Forum / Coding / FMODE=3


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#1 - Posted: 2 Apr 2023 04:08 - Edited
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Hi.. for fun I have started coding for amiga again..

I had an old project that never finished, that I wanted too tinker with.

so for purly fun I have been playing around with Bartman's exellence VSCode plugin.

this old project had the graphics in Screen size 368x283..

Back in the old days I never figured out how to open this screen size with FMODE=3..

I have aligned Bitplanes to 64bit. So bitplane width becomes 384x283. with using mod -8.

My currect copper settings uses this

[ Screen1 ] Mem: 0000A41C | Adr: 0000A440 | Size: 109120
[ DDFSTRT ] 092: 0028
[ DDFSTOP ] 094: 00D8
[ DIWSTRT ] 08E: 1F61
[ DIWSTOP ] 090: 3AD1

I'm not really sure whats wrong here.. but there are clearly a problem. The graphics repeat at the left side and the right side is being cut off.

Any sugestions are more than welcome

Corrupted Graphics

Note: Yes I know the palette is wrong.
#2 - Posted: 5 Apr 2023 13:23
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you have to make sure the "horizontal datafetch" and mod are set so the bitmap will restart with a multiple of eight at *each lines*. Plus, On UAE it does repeating, but on real hardware it crashes the machine very hard.

... some years ago I did a 320x AGA copperlist with horizontal scroll and FMOD=$33, so no overscan but I had to consider 48 bytes per plane/line.

#3 - Posted: 9 Apr 2023 00:42
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Thanks you.

I have now something too focus on.. I have been looking at Hardware setup, if I missed some bits.
#4 - Posted: 14 Apr 2023 20:28 - Edited
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For our demo "The ventures of Prince Dakkar and his pilgrimage to the abyss" we used overscan 384x170, C2P skipped only visible pixels.

This is the copper settings we used:
[ DDFSTRT ] 092: 0018
[ DDFSTOP ] 094: 00a0
[ DIWSTRT ] 08E: 555C
[ DIWSTOP ] 090: FDD4
[ BPLCON1 ] 102: 7777
[ DIWHIGH ] 1E4: E000
[ FMODE ] 1FC: 0003

Hope it helps!
#5 - Posted: 15 Apr 2023 13:50
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Ohh that is good timing ..

I had it working in winuae but on real hardware I found out the Screen was off center ..

so i'll give your values a test .. thanks.


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