DIY Coprocessors For The Game Boy Color

Back in the olden days, when video games still came on cartridges, the engineers and programmers making these carts had a lot of options. One of the most inventive, brilliant, and interesting cartridges to come out of the 90s was Star Fox for the Super Nintendo. Star Fox featured a coprocessor chip, the Super FX, that was effectively a GPU used to draw polygons in the frame buffer. Without this, Star Fox wouldn’t be 3D, Yoshi’s Island wouldn’t be as cute, and there wouldn’t be an always-on processor in your computer with the potential to spy on everything you do.

gameboy-coprocessor-cartridgeThe Super FX chip, the Capcom-developed Cx4 coprocessor, and the Nintendo DSP all lived in a cartridge, but the technology to put a better computer in a cartridge never made it to Nintendo’s handheld devices. Cheap, powerful microcontrollers are everywhere now, and it’s not that hard to make a board with card edge connectors, leading [Anders] to build a Super FX for the Game Boy Color.

Game Boy cartridges are simple — just a memory controller and some memory is all you need. Drop in a microcontroller, and you have a Game Boy coprocessor. This cartridge features the MBC1 memory bank controller, 512kB of Flash, and 8KB SRAM. These are fairly standard parts, but there’s one last trick up the sleeve of this board: a KE04 from NXP, an ARM Cortex-M0+ microcontroller running at 48MHz . This microcontroller is, effectively, the GPU for the Game Boy.

This ARM-powered coprocessor is able to convert the framebuffer into tiles in just 2ms, giving the system plenty of time for image processing and rendering. Due to the limitations of the Game Boy, the best resolution offered by this coprocessor is either 160×96 or 128×128 pixels, short of the complete 160×144 pixel display in the Game Boy Color.

Even though [Anders] is still working on programming this thing to show off the power of his Game Boy coprocessor, he has a few demos to show off. The most impressive is a Wolfenstein-like clone. That’s extremely impressive and categorically impossible on a stock Game Boy Color.

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Overclocking a Starfox game cartridge

Some of our younger readers will never have experienced this before, but back in the day your video games would slow way down if there were too many moving objects on the screen. The original Castlevania comes to mind, but many will remember the problem while playing the fantastically three-dimensional Super Nintendo game Starfox. [Drakon] isn’t putting up with that hardware shortfall any longer, he hacked this cartridge to run at 42 MHz, twice as fast as the design spec.

We only occasionally look in on the cart hacking scene so it was news to us that three different versions of a pin compatible chip were used in this hardware. The first two suffer from the slowdown problem, but the final revision (SuperFX GSU 2) doesn’t. It can also be overclocked as high as 48 MHz but because of the video frame rate you won’t see added improvement with the extra 6 MHz.

[Drakon] used a Doom cartridge as a guinea pig because it offers the most RAM, and set to work rerouting the traces for the ROM chip to an EEPROM so that the hardware can be used with different games. He also took this opportunity to patch in the faster clock signal.

Snega2usb preorder now available

We’ve been watching the development of the snega2usb since it’s debut on Hackaday. Now it’s grown up and is ready to be manufactured. In the low quality video above [Matthias] shows some of the latest high quality additions to the board. It now has a case, shiny new firmware,  production made PCB, and game pad ports.  The snega2usb is shipping this December for those who preorder now.

snega2usb update: usb snes and sega cartridge reader

When we first posted [Matthias_H]’s USB reader for SNES game carts, it was met with enthusiasm. The snega2usb allows you to play SNES and Sega games on your pc right off the cartridge. The latest revision is even more amazing than the first.  [Matthias] has added the ability to read Sega Genesis/Mega Drive cartridges as well as the ability to save games directly to the cartridge. The board has also been updated from the rats nest it used to be to a smart looking dual sided PCB. So far [Matthias] hasn’t had any trouble reading cartridges, even ones with the SuperFX chips. [Matthias] also launched a site for the project where the lastest information on its development can be found.  [Matthias] is getting close to a production version which will feature better firmware, console quality connectors and a shiny case.