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Action Replay/Gameshark codes

Discussion in 'Engineering & Reverse Engineering' started by re-inferno, Jul 13, 2005.

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  1. re-inferno

    re-inferno

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    example:

    Code for infinite rings for the European Sonic2 would be

    FFFE21 00FF

    Now can anyone tell me how to modify the adress offset so that this code works for a US Sonic 2 version? (in Gens for example)

    Or is there good link that describes anything ARP/Genesis related?
     
  2. Elusive

    Elusive

    Sparkster the Rocket Knight Member
    Sonic 2 is the same game, no matter what region it is played it. European Sonic 2 is the same as American Sonic 2, for example. Anything, including codes, should work the same for an 'European' Sonic 2 ROM as it does for an 'American' Sonic 2.

    Unless by which you mean A and B 'version' codes, but I don't understand them either, what with the game being universal.
     
  3. re-inferno

    re-inferno

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    no.

    inserting "FFFE21 00FF" in Gens does nothing, it only works with Codes starting with 00... or 0... which in the ARP-Codebook are referred to as "JAP" or "US" Version codes.
    I somewhere read thet there's a difference in the offset adress.. can't remember, and comparing "US" "JAP" and "EUROPEAN" codes from the book that have the same effect, I can't find a pattern.

    I would need that conversion to show that Sonic 2 contained an alternate Super Sonic palette that was later used for S&K's Hyper Sonic, (if it's not already known) but I only have the code found on the (European) genesis/sonic 2, so no proof till I find a conversion.
    (oh yeah, I could rig up the real hardware and make serveral photographs of the animated palette :P )
     
  4. ICEknight

    ICEknight

    Researcher Researcher
    Gens handles PAR codes incorrectly, so try Kega Fusion instead.

    UK version = European version
     
  5. drx

    drx

    mfw Researcher
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    try putting a ':' between the address and the value. eg. FFFE21:00FF

    btw, rings are at FFFE20, so FFFE20:0063 would be better.
     
  6. Aurochs

    Aurochs

    Единый, могучий Советский Союз! Tech Member
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    Well, that just gives you 99 rings. =P

    Try putting in FFFE20:7FFF. That comes out to decimal 32,767, which is effectively infinite. Don't know how the HUD will react to that number, though.

    And fuck! I've been editing savestates to get 7 emeralds (for testing my hack), and I completely forgot about PAR codes! Damnit...
     
  7. drx

    drx

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    :rolleyes:
    when you use those codes in gens, their frozen anyway.
     
  8. LocalH

    LocalH

    roxoring your soxors Tech Member
    I'm pretty sure that the A and B codes are just for either rev.0 or rev.1 (and if I remember correctly, that was the case more so with the Game Genie than the PAR). I've not looked at them in detail recently, but I'm pretty sure that there's some difference in terms of where exactly ROM code is located in the binary. However, I'm pretty sure that RAM locations didn't change across revisions, so that code should work. Since rings is a word value, by modifying FFFE21, you're modifying just the least-significant byte, forcing the game to always give you a low byte of FF.

    Also, as has been said, Sonic 2 is Sonic 2 is Sonic 2. If the A code doesn't work, use the B code equivalent, and vice versa. Sonic 2 is one of the games that doesn't care about the region. It does check the 50/60Hz flag, but only to correct the music tempo (despite that debate we had here a while back, I never saw concrete proof either way, so I revert to the belief I hold by inspecting the game's behavior in Kega, especially after booting at one frame rate and then switching to the other without rebooting).

    If you use PAR codes on hardware, make sure to split it after the 5th hex digit in the address part, but other than that, the codes work directly on hardware, both ROM and RAM hacks. So FFFE21:00FF turns into FFFE2 100FF on a real PAR.
     
  9. LOst

    LOst

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  10. re-inferno

    re-inferno

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    Ok, thank you!
    I got it running with Kega Fusion (Gens/+ really seem to only accept codes that start with 00 or Game Genie codes...)
     
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