Super gameboy color?

Discussion of programming and development for the original Game Boy and Game Boy Color.
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ceriux
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Super gameboy color?

Post by ceriux » Sun Nov 01, 2015 1:14 pm

Hey i was doing some reading and i found out that you can actually mod a super gameboy cartridge and add a link cable port. i also read that the only extra chip from the super gameboy (compared to a regular gameboy) is a chip that grabs video and button input. would it be possible to gut a gameboy color and solder on all the stuff to the super gameboy cart and convert it to a super gameboy color?

or are the gameboy and gameboy color systems far too differnt? just a thought figured i'd ask?

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Re: Super gameboy color?

Post by lidnariq » Sun Nov 01, 2015 1:25 pm

The video output from the DMG is just a 2bpp stream, and a full frame of that data is only 160×144×2÷8=5760 bytes. The Super Gameboy works by using the SNES's DMA to copy those 6KB of data into the SNES's PPU.

However, the GBC emits a 15bpp stream, requiring eight times as much data to be transfered, and the SNES can't keep up.

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ceriux
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Re: Super gameboy color?

Post by ceriux » Sun Nov 01, 2015 1:34 pm

thanks for the info glad i didnt try this on my own !

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Re: Super gameboy color?

Post by tepples » Sun Nov 01, 2015 1:41 pm

That's why Nintendo waited until the GameCube era to make something like this, as its "high-speed port" is fast enough to pass GBC or GBA full-color output.

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Re: Super gameboy color?

Post by ccovell » Sun Nov 01, 2015 3:46 pm

tepples wrote:That's why Nintendo waited until the GameCube era to make something like this, as its "high-speed port" is fast enough to pass GBC or GBA full-color output.
N64 era. There are CGB and GBA WideBoy64s.

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Re: Super gameboy color?

Post by tepples » Sun Nov 01, 2015 4:12 pm

Yet they weren't produced in quantity. Was there some limit of the N64 cart bus preventing this? Frame rate problems? Or was it just Nintendo being a dog in the manger?

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Drew Sebastino
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Re: Super gameboy color?

Post by Drew Sebastino » Sun Nov 01, 2015 6:36 pm

tepples wrote:Was there some limit of the N64 cart bus preventing this?
Well, he just gave an example. :/ The amount of them has nothing to do with if they actually work. I find it incredibly hard to believe that the N64 can't stream 4x the amount of data as the SNES.

Anyway though, Would it be possible to actually just use the SNES's video hardware to emulate the GBC's instead of just sending a pre competed image? Oh, wait, the GBC has 32 palettes, 16 for sprites and 16 for BGs, doesn't it... I was about to suggest that you'd just use half of the bits for sprites, and use a 2bpp BG layer, but then I also remembered that color 0 on each BG palette is a unique color. At least with the BG though, you can layer 2 2bpp layers on top of each other, with one of the layers having tiles being a solid color (presumably any regular tile, just with all 4 entries in the palette being the same). Actually, you could still have the GBC BG layer on the SNES if you use all 4 2bpp layers in mode 0: have 2 BG layers, each for 8 palettes, and have the other 2 BG layers be the palettes of color 0. I'm still at a loss with sprites though, unless you want to have a "copy" of every 2bpp sprite graphic so that you can use the top 8 colors as an extra palette. I'm not sure how feasible this would be though. The BG should be fine though.

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Re: Super gameboy color?

Post by tepples » Sun Nov 01, 2015 6:39 pm

GBC has 8 palettes for backgrounds and 8 palettes for sprites, just like the Super NES. BUT: Color 0 of each background palette is significant, unlike the Super NES where only the first background palette's color 0 is ever used. And there's CHR HDMA to quickly move data from ROM or RAM to VRAM. And a lot of games rewrite background palettes during draw time.

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Drew Sebastino
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Re: Super gameboy color?

Post by Drew Sebastino » Sun Nov 01, 2015 6:56 pm

tepples wrote:GBC has 8 palettes for backgrounds and 8 palettes for sprites, just like the Super NES. BUT: Color 0 of each background palette is significant, unlike the Super NES where only the first background palette's color 0 is ever used.
Well, like I was saying, just have it to were there are 2 2bpp BG layers, one with solid tiles that goes behind the regular one. Just thinking, you would actually need to have an extra solid tile somewhere in vram. I doubt the GBC will use it all.
tepples wrote:And there's CHR HDMA to quickly move data from ROM or RAM to VRAM. And a lot of games rewrite background palettes during draw time.
How much data can you change each scanline?

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Re: Super gameboy color?

Post by tepples » Sun Nov 01, 2015 7:00 pm

Espozo wrote:Well, like I was saying, just have it to were there are 2 2bpp BG layers, one with solid tiles that goes behind the regular one.
It would take all four layers (background color 0, window color 0, background, window), leaving no room for a border.
Espozo wrote:
tepples wrote:And there's CHR HDMA to quickly move data from ROM or RAM to VRAM. And a lot of games rewrite background palettes during draw time.
How much data can you change each scanline?
HDMA on GBC copies 16 bytes after each of up to 144 scanlines.

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Drew Sebastino
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Re: Super gameboy color?

Post by Drew Sebastino » Sun Nov 01, 2015 7:14 pm

tepples wrote:window
Wait, what?
tepples wrote:HDMA on GBC copies 16 bytes after each of up to 144 scanlines.
Well, then that's perfect, isn't it?
tepples wrote:leaving no room for a border.
I didn't really expect to have enough resources for a border...

Actually, wait, why not just make a border with sprites? This whole thing will probably be more limited than the regular Super Gameboy, but that's what I was expecting.

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Re: Super gameboy color?

Post by Dwedit » Mon Nov 02, 2015 8:26 am

There are very few games programmed to properly support both GBC and SGB mode simultaneously. Some games go to color, but then restrict the graphics quality because it's a SGB. I've heard of one game that properly supports SGB and GBC mode at the same time (full color, then changes the border periodically).
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ceriux
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Re: Super gameboy color?

Post by ceriux » Wed Nov 04, 2015 3:33 am

I just wish I could play my pokemon games in full color :(

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Re: Super gameboy color?

Post by lidnariq » Wed Nov 04, 2015 11:16 am

Why not get a used gamecube and gameboy player?

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tokumaru
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Re: Super gameboy color?

Post by tokumaru » Wed Nov 04, 2015 11:56 am

lidnariq wrote:Why not get a used gamecube and gameboy player?
I considered doing this, but optical drives have the annoying tendency to fail, and considering how old the GameCube is, I wouldn't expect a used one to last very long. If only you didn't need to use a disc in order to boot the Game Boy hardware...

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