PC Engine SuperGrafx mod

Started by thumpin_termis, January 02, 2007, 08:13:46 AM

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Just wondering out loud for those who may want to mod a SuperGrafx system.   I don't know if anyone has even thought about this very minor issue (but annoying to some - like me!), but if anywhere, I'm sure this is the place to find such people.

According to multimods.com, 2 games will not work correctly with a modded SuperGrafx for some reason.  

Quote*  Certain games have known issues with region mods on the SuperGrafx system:

       1. Aldynes - plays fine, but if you allow the system to go into Attract Mode (demo at beginning), it will freeze.
       2. Space Harrier - game apparently loads and then quickly freezes.

The ONLY reason that I can think of Aldynes (a jp supergrafx game) freezing up is because of the pin 29 ground mod - which would be required only to play US games, not JP games.  This is because once the switch is set to JP mode, the whole entire logic of the system is EXACTLY the same as an unmodded system, MINUS the aforementioned pin 29 of HuC6280.  

And I'm not sure which version of Space Harrier (regular pc-engine HuCard game) he was mentioning, but if it's just the JP version that freezes, then it's got to be the same issue as above.  If both or just the US version of the Space Harrier has this problem, I can only guess it'd be some kind of internal compatibility issue with the SGX and would give up on this problem.

Now, if not grounding pin 29 cures the problems the above two games, then one can either:
1. Use an SPDT switch just to either ground or not to ground pin 29 of HuC6280.
2. Add a DPDT switch instead of the SPDT switch to the known ic mod, and have one side control the ICs like it normally would, and the other side control the ground of pin 29.
3. Find a 9PDT(!) switch and do the same as the known 8PDT switch mod, except this 9PDT switch would also control the ground of pin 29 in addition to the 8 data pins.  (Can you even buy a 9PDT switch? You might have to custom build this one, which in case, might as well go with option 2!)

Okay, so maybe this is a whole lotta rambling for just 2 games, but if the above works, this would be the ONLY true way to get a system that plays 100% of the chip games.  That's gotta be worth something, no?   :P

So anyone knows/thought about this issue, please post!


As far as I know Space Harrier fails because the SGX is in SuperGrafx mode.  I'd be surprised to find it fails to run if the system's in PCE mode.


QuoteAs far as I know Space Harrier fails because the SGX is in SuperGrafx mode.  I'd be surprised to find it fails to run if the system's in PCE mode.
Ah, that could be it.  Unfortunately, I don't have a copy of Space Harrier to test it out...

Anyone get Space Harrier working okay on a SuperGrafx system, modded or not?