Nyan Cat NES

Discussion in 'Nintendo Game Development' started by derekb, Aug 11, 2011.

  1. l_oliveira

    l_oliveira Officer at Arms

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    MMC3 is the most common mapper chip, the most powerful of the common mappers, with controls for both chr and prg banking, mirroring type and it has a scanline counter for dividing the screen...

    You can't go wrong with MMC3.
     
  2. Calpis

    Calpis Champion of the Forum

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    It would be incredibly wasteful for a demo like this to be written for MMC3 since NROM *16/8* is more than sufficient for the animation and music here! Hell, this kind of demo doesn't even need CHR-ROM, you'd have space left over if you used internal VRAM for CHR >_< Also the Mega Man games don't make extensive use of CHR bankswitching, most (MM1,MM2,MM4,MM6) use CHR-RAM so no bankswitching at all. CHR-RAM allows for much better animation (tile granularity) at the cost of CPU time and code complexity since you'll have to schedule and prioritize VRAM updates and probably implement a variable framerate.
     
    Last edited: Aug 28, 2011
  3. aliman

    aliman Member

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    by da way: today's ma 16th^^
     
    Last edited: Sep 1, 2011
  4. l_oliveira

    l_oliveira Officer at Arms

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    I suggested the MMC3 because it's powerful, useful (for other projects) and is the most common mapper out there.

    Last thing I was thinking of was saving resources... ;-)
    More like saving hassle ... :thumbsup:

    Megaman games with CHR-RAM:

    MEGAMAN (UNROM)
    MEGAMAN2 (MMC1 CHRAM)
    MEGAMAN4 (MMC3 CHRAM)
    MEGAMAN6 (MMC3 CHRAM)

    Megaman Games with CHR-ROM:
    MEGAMAN3 (MMC3 CHROM)
    MEGAMAN5 (MMC3 CHROM)

    :thumbsup:
     
    Last edited: Sep 1, 2011
  5. derekb

    derekb Well Known Member

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    I'm having a trouble doing palette cycling and was wondering if anyone could help, when I change a palette color my entire background winds up pushing itself down for some reason, my lil code snip is

    Code:
     
    lda	 $2002 
    lda #$3F 
    sta $2006 
    lda #$00 
    sta $2006 
    lda #$0F 
    sta $2007 
    RTS 
    
    before:

    [​IMG]

    after code runs:

    [​IMG]

    (the boxes on top are just reference points to see whats happened)

    if anyone has an idea off top of their head of what would cause this please lmk
     
  6. aliman

    aliman Member

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    is the project still going on?
    just asking^^
     
  7. derekb

    derekb Well Known Member

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    yeah I'm just really really busy lately, someone on nintendoage offered me some help I just havent had time to look into it
     
  8. aliman

    aliman Member

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    cool^^
    can't wait for the next release:thumbsup:
     
  9. derekb

    derekb Well Known Member

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    friendly update, I finally got around to working on this again, added time counter for how long you've been nyan'ing for
     
  10. derekb

    derekb Well Known Member

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    bumping because I'm still having that palette issue, writing to memory does modify the palette correctly but then my nametable winds up scrolling and I really don't get why it's happening, any help appreciated

    just modifying palette with a simple

    LDA #$3F
    STA $2006
    LDA #$00
    STA $2006


    LDA #$06
    STA $2007
     
  11. Calpis

    Calpis Champion of the Forum

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    Are you setting $2006 to #$0000 when you're done with it? $2006 is used by the PPU for rendering outside of Vblank.
     
  12. derekb

    derekb Well Known Member

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    you know what I am not, lemme try that and see if it fixes it, I implemented a workaround but proper code use would def be better :)

    also I will be done with this rom this weekend, I added a nice counter for how long youve had nyan cat going as well as a reverse Tac Nayn mode

    edit: that fixed it, thanks for correcting my oversight Calpis
     
    Last edited: Jun 13, 2012
  13. H360

    H360 Familiar Face

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    First link is DOOOOOOOOOOMED by Megaupload

    [​IMG]
     
  14. derekb

    derekb Well Known Member

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    first link was really outdated anyway, heres the latest video, I've since moved some of my CHR tiles around so that I can add the actual tac nayn graphics

     
    Last edited by a moderator: May 25, 2015
  15. H360

    H360 Familiar Face

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    That is excellent! A real great job you have done right there.

    Only suggestion I have, is to make one of the buttons hide / show the timer.
     
  16. derekb

    derekb Well Known Member

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    added the Tac Nayn sprite swap in
     
  17. derekb

    derekb Well Known Member

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    ay ay ay, calpis I'm having another palette issue, ive pmd you

    basically for some reason every once in awhile my overwriting of the palette bytes will mess up and wind up placing a value in the wrong position, pardon the length of code, I was looping but wanted to make sure it was definitely not the loop

    LDA #$2002
    LDA #$3F
    STA $2006
    LDA #$00
    STA $2006

    ; update bg palette
    LDA #$0F
    STA $2007
    LDA #$10
    STA $2007
    LDA #$20
    STA $2007
    LDA #$30
    STA $2007
    LDA #$0F
    STA $2007
    LDA #$00
    STA $2007
    LDA #$10
    STA $2007
    LDA #$2D
    STA $2007
    LDA #$0F
    STA $2007
    LDA #$3D
    STA $2007
    LDA #$10
    STA $2007
    LDA #$30
    STA $2007
    LDA #$0F
    STA $2007
    LDA #$10
    STA $2007
    LDA #$20
    STA $2007
    LDA #$30
    STA $2007


    ; update sprite palette
    LDA #$2002
    LDA #$3F
    STA $2006
    LDA #$10
    STA $2006


    LDA #$0F
    STA $2007
    LDA #$10
    STA $2007
    LDA #$20
    STA $2007
    LDA #$30
    STA $2007
    LDA #$0F
    STA $2007
    LDA #$00
    STA $2007
    LDA #$10
    STA $2007
    LDA #$2D
    STA $2007
    LDA #$0F
    STA $2007
    LDA #$3D
    STA $2007
    LDA #$10
    STA $2007
    LDA #$30
    STA $2007
    LDA #$0F
    STA $2007
    LDA #$10
    STA $2007
    LDA #$20
    STA $2007
    LDA #$30
    STA $2007


    LDA #$00
    STA $2006
    LDA #$00
    STA $2006

    for the most part this works correctly, but occasionally one of the values gets written into the wrong position and throws the entire purpose off, does anyone have any suggestions?
     
    Last edited: Jun 15, 2012
  18. derekb

    derekb Well Known Member

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    built my first cart version of the rom, works fine except for the switch to Tac Nayn, palette either glitches out like I already knew happened, or for some reason a background tile wil randomly change which doesnt happen in any of the emulators, will have to muck with it some more i guess
     
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