2021-01-06 03:52:10 +00:00
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Apple II Cycle Counting Megadmo
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Demosplash 2018 1st place Retro Demo
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by Vince "deater" Weaver, VMW Productions
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2018-09-26 18:01:14 +00:00
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Memory Map:
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$0000-$0100 = ZERO PAGE
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$0100-$0200 = STACK
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$0400-$0800 = TEXT/GR PAGE0
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$0800-$0C00 = TEXT/GR PAGE1
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$0C00-$0fff = we use this as TEXT/GR offscreen buffer
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$1000-$1fff = 4k free
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$2000-$3fFF = HGR1 page ; note we never use HGR2 ($4000-$6000)
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$4000-$9600 = roughly 20k(?)
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$9600-$BFFF = DOS3.3
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$C000-$FFFF = peripherals/ROM
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2018-10-02 04:32:57 +00:00
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Largest can load from $4000 to $9600 = 22,016
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Largest can load from $1000 to $9600 = 34,304
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$4000-$C000 = 32768
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2018-09-29 17:24:13 +00:00
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C64:
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Apple II:
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Starring:
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Three pages page flipping. Hires colors subset of Lores so
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can replicate a blocky color image. Could in theory animate this
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at 60Hz. Also could flip between 4 pages, but need the 8k of
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HGR page2.
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2018-10-01 03:07:57 +00:00
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For cycle-counting timing, jmp one into a bit $C055 instruction
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which is EOR $C0,X (4 cycles)
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2018-10-01 05:34:41 +00:00
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Note, discover that the LORES and HIRES pages aren't exact matches
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for each other, even when using same color. Half-pixel off?
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2018-09-29 17:24:13 +00:00
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E-mail:
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Half screen text, half 40x96 lores.
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Text is also interlaced top/bottom to create new chars (including
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some lowercase) on Apple II+ and before w/o lower case.
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Trouble as the built-in font is offset a frame on II vs IIe?
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Also annoyance, my GR compressor uses Grey2 (color $a) as encoding,
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which means can't use a GR image to hold plain black spaces (char $a0)
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