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Space Invaders for Super Game Boy
http://forums.nesdev.com/viewtopic.php?f=12&t=1191
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Author:  dXtr [ Sat Mar 04, 2006 1:04 pm ]
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tepples wrote:
See Space Invaders, which had separate engines for Game Boy (GBZ80) and Super NES (65C816 + SPC700).


sorry.. I know this a bit OT, but is there any documentation on how this actually worked? it could be intresting as an alternate method for snes homebrew coders to try out their code on a snes using a super gameboy and a gb flash cart. or is this a just a bad idea?

Author:  Bregalad [ Sat Mar 04, 2006 2:27 pm ]
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Sorry, I don't know much about Space Invaders. It is a gameboy cart that has special things when played trough a Super Game Boy ? The game has direct acess to SNES CPU and APU ?
Game faqs record it as have two separate version for Game Boy and SNES.

Author:  tepples [ Sat Mar 04, 2006 2:50 pm ]
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Bregalad wrote:
Sorry, I don't know much about Space Invaders. It is a gameboy cart that has special things when played trough a Super Game Boy ? The game has direct acess to SNES CPU and APU ?
Game faqs record it as have two separate version for Game Boy and SNES.

Three versions were reviewed in Nintendo Power:
  1. A Game Boy version
  2. A Super Game Boy version, which contained both a Game Boy version and a Super NES version
  3. A Super NES version, which also had a 2-player simultaneous mode

Author:  dXtr [ Sat Mar 04, 2006 5:18 pm ]
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I did some searching on the super gameboy and found this text file:
http://www.rawer.de/marc/Gameboy/Docs/Sgb.txt

it describes the commands used by the super gameboy games..

but I couldn't really find any clues on how they managed to boot the snes version of space invaders from the gb cartridge.

Author:  cdoty [ Sat Mar 04, 2006 6:08 pm ]
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dXtr wrote:
I did some searching on the super gameboy and found this text file:
http://www.rawer.de/marc/Gameboy/Docs/Sgb.txt

it describes the commands used by the super gameboy games..

but I couldn't really find any clues on how they managed to boot the snes version of space invaders from the gb cartridge.


It ran as a normal GB cartridge, and was able to send commands to the SNES. There's a document somewhere about the communication protocol. I think it was able to send over code blocks (But, if I remember correctly it was limited in size). It's also how they set the boarders for game (Donkey Kong was one of them if I remember correctly). There was a homebrew rom that utilized the SGB.

Here's another document about the SGB:
http://www.devrs.com/gb/files/sgbhard.txt

Author:  tepples [ Sat Mar 04, 2006 7:14 pm ]
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(using names given in Sgb.txt)

I'm guessing Super NES WRAM Transfer ($0F, $10), GameBoy Window Mask ($17), and Set Program Counter ($12). The format for "CharSet Transfer" tiles is exactly the same as the normal Super NES or PC Engine tile format.

Author:  dXtr [ Sun Mar 05, 2006 6:13 am ]
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so they transferd the program over into the snes ram and set the 65816's program counter to that ram adress, is that what you mean?

Author:  tepples [ Sun Mar 05, 2006 9:49 am ]
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That's what I'm guessing. Space Invaders looks as if it could be small enough to fit in RAM.

Author:  dXtr [ Sun Mar 05, 2006 10:56 am ]
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yeah, it sounds like the moste probable way they did it. but I was kind of hoping that it was executed directly from the gb cart. =/
oh well.. then I know it possible to a certain extent to test code this way.

Author:  tepples [ Sun Mar 05, 2006 12:48 pm ]
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And there's a lot more usable PRG RAM in the Super NES than in the NES (128 KB vs. 2 KB).

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