• Summer Games

    From Andreas Kohlbach@3:770/3 to All on Saturday, June 08, 2019 16:45:02
    I was recently playing Summer Games by Epyx on the Commodore 64 (well in
    an emulator). I noticed again the smooth animation of the guy with the
    torch lightning the Olympic Fire. I was stunned back in 1984 when I saw
    it on the real machine.

    Only today I notice that the guy, the fire and eight doves were on the
    screen at the same time at some point. I would imagine these are all
    sprites. But the C64 only had eight hardware sprites. But with eight
    doves, the torch carrier and possibly the flame after being ignited I
    count at least ten sprite. How did they pull it off?
    --
    Andreas

    My random thoughts and comments
    https://news-commentaries.blogspot.com/

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  • From Tom Lake@3:770/3 to Andreas Kohlbach on Saturday, June 08, 2019 14:56:42
    On Saturday, June 8, 2019 at 4:45:03 PM UTC-4, Andreas Kohlbach wrote:
    I was recently playing Summer Games by Epyx on the Commodore 64 (well in
    an emulator). I noticed again the smooth animation of the guy with the
    torch lightning the Olympic Fire. I was stunned back in 1984 when I saw
    it on the real machine.

    Only today I notice that the guy, the fire and eight doves were on the
    screen at the same time at some point. I would imagine these are all
    sprites. But the C64 only had eight hardware sprites. But with eight
    doves, the torch carrier and possibly the flame after being ignited I
    count at least ten sprite. How did they pull it off?
    --
    Andreas

    My random thoughts and comments
    https://news-commentaries.blogspot.com/

    As long as the doves stay in the sky and the fire stays OUT of the sky and away
    from the ground, they might have used vertical interrupts to switch sprite sets
    as the electron beam hit certain parts of the screen. Think of it like a layer cake. Each
    layer can have up to eight sprites which are independent of the sprites in any other layer. On the 64, the layers can be different widths. You can have dozens
    of sprites on the screen at the same time but each group of eight can only stay
    in its own
    layer.

    --- SoupGate-Win32 v1.05
    * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)
  • From Frank Linhares@1:229/101 to Tom Lake on Saturday, June 08, 2019 20:32:30
    As long as the doves stay in the sky and the fire stays OUT of the sky
    and away from the ground, they might have used vertical interrupts to switch sprite sets as the electron beam hit certain parts of the screen. Think of it like a layer cake. Each
    layer can have up to eight sprites which are independent of the sprites
    in any other layer. On the 64, the layers can be different widths. You
    can have dozens of sprites on the screen at the same time but each group of eight can only stay in its own
    layer.

    Many of the demo scene demos from back in the day (and currently) took advantage of vertical interrupts to make incredible demos. I would bet that Epyx did the same.

    frank%netsurge%demonic
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  • From Andreas Kohlbach@3:770/3 to Frank Linhares on Sunday, June 09, 2019 17:03:26
    On Sat, 08 Jun 2019 20:32:30 +1300, Frank Linhares wrote:

    As long as the doves stay in the sky and the fire stays OUT of the sky and away from the ground, they might have used vertical interrupts to switch sprite sets as the electron beam hit certain parts of the screen. Think of it like a layer cake. Each
    layer can have up to eight sprites which are independent of the sprites in any other layer. On the 64, the layers can be different widths. You can have dozens of sprites on the screen at the same time but each group of eight can only stay in its own
    layer.

    Many of the demo scene demos from back in the day (and currently) took advantage of vertical interrupts to make incredible demos. I would bet that Epyx did the same.

    Thank you and Tom. So vertical interrupts might made this
    happen. Amazing, because in 1984 the Commodore 64 was only two years old.
    --
    Andreas

    My random thoughts and comments
    https://news-commentaries.blogspot.com/

    --- SoupGate-Win32 v1.05
    * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)
  • From Tom Lake@3:770/3 to Andreas Kohlbach on Sunday, June 09, 2019 15:18:35
    On Sunday, June 9, 2019 at 5:03:27 PM UTC-4, Andreas Kohlbach wrote:
    On Sat, 08 Jun 2019 20:32:30 +1300, Frank Linhares wrote:

    As long as the doves stay in the sky and the fire stays OUT of the sky and away from the ground, they might have used vertical interrupts to switch sprite sets as the electron beam hit certain parts of the
    screen.
    Think of it like a layer cake. Each
    layer can have up to eight sprites which are independent of the
    sprites
    in any other layer. On the 64, the layers can be different widths. You can have dozens of sprites on the screen at the same time but each
    group
    of eight can only stay in its own
    layer.

    Many of the demo scene demos from back in the day (and currently) took advantage of vertical interrupts to make incredible demos. I would bet that Epyx did the same.

    Thank you and Tom. So vertical interrupts might made this
    happen. Amazing, because in 1984 the Commodore 64 was only two years old.
    --
    Andreas

    My random thoughts and comments
    https://news-commentaries.blogspot.com/

    The technique was documented in the Commodore 64 Programmer's Reference manual which was available at the beginning of January 1983 so it wasn't one of those hidden features that had to be discovered by users.

    Tom L

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  • From Frank Linhares@1:229/101 to Andreas Kohlbach on Sunday, June 09, 2019 20:03:34
    Thank you and Tom. So vertical interrupts might made this
    happen. Amazing, because in 1984 the Commodore 64 was only two years old.

    Between the VI's, Sprites and the SID chip; it was the best selling perswonal computer. It pushed limits way beyond limits.

    frank%netsurge%demonic
    disksh0p!bbs // bbs.diskshop.ca // mystic goodness
    home of SciNet // https://diskshop.ca/scinet

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