Reset from Sega CD Quirks

Discussion in 'Technical Discussion' started by Bibin, Jun 4, 2012.

  1. Bibin

    Bibin

    DON'T LET THE SUN LAUGH AT YOU. Member
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    Ghost in the Machine
    Noticed a little funsy today.

    I've always played with the fact that if you throw a cartridge into the genesis while CD music is playing, it'll crash the Sega CD software but the music continues to play off the CD (looping, in fact). Resetting lets the music continue to play (custom soundtracks!) and the cart game will start up.

    I only noticed today though that RAM isn't cleared whatsoever during this reset process, allowing for some fun:

    http://www.youtube.com/watch?v=u1EmgeAXB-4

    I've tried this on my CDX, and unfortunately the cd music stops on reset.

    Is this because my first genesis has no TMSS that this works at all?
     
  2. sasuke

    sasuke

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    I know that part of the reason why the Sega CD software crashes when the cart is inserted is because of the way the Sega CD is mapped in the address bus. When there is no cart, the CD BIOS and RAM are at the beginning of the address bus. When the cart is inserted, the cart is at the beginning and the BIOS is 4MB after it.

    I assume that the CD continues looping because the SUB-CPU program isn't touched after the cart is switched, and the Sega CD does not reset when the Geneis does, so it continues to run. The CDX could be stopping because they share the same reset line, unlike the stand alone Genesis and Sega CD. The TMSS program also does not touch any Sega CD hardware, so that might not be the problem.

    Also, interesting SOR glitch. :)
     
  3. dsrb

    dsrb

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    OT: Has anyone properly hacked SoR2 to have difficulty beyond Mania? If the mode you glitched into is harder – which it definitely seems – then there should be a way to do it properly and with greater control over whichever settings, algorithms, etc. are involved. It may well be as simple as changing a few values in RAM, but deliberately this time.
     
  4. Bibin

    Bibin

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    Ah, I forgot Mania exists - is the mode I seem to have it playing in definitely harder than mania, or is it just mania?
     
  5. Sik

    Sik

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    being an asshole =P
    The game doesn't show Mania in the options screen, so no. Probably it's set to some out-of-range value, and thereby it's reading the difficulty parameters out of some random place (in other words, garbage). Meaning don't expect it to make any sense at all.

    Reminds me of how I had SOR1 in some bootleg 4-in-1 cart and it wouldn't clear the options. The result is that the default difficulty is garbage. One of the values you could get (if you pressed left it wouldn't trigger the range check) actually made the third boss lose in 1 hit. Conveniently appropriate because I used to have problems with that one boss. The game in general seemed harder in that setting though...
     
  6. Ravenfreak

    Ravenfreak

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    Hacking Sonic Drift, Writer at Sonic Cage Dome
    So I tried this out on my Model 2 Sega CD, and the game never boots up all the way. (It locks up after the licensed by sega screen...) and I don't have a Genesis without the TMSS so I'm not sure if that's the reason why it won't boot up or if it's because I have a Model 2 Sega CD. However this is rather interesting. xD