Hacking nitro2k01's SGB Enabler for EZ Flash Jr

nitro2k01

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As many people here might know, EZ Flash Jr doesn't work well with SGB. While we're waiting for an official solution from EZ Flash Team, I've developed my own, basically software only, solution for it. It's a modified version of the EZ Flash Jr kernel 1.04e. This is beta software, and I would appreciate feedback from anyone interested in using it, especially on a NTSC SNES or on a SGB2.

FAQ:
What was the problem and how does the SGB Enabler work?
The SGB contains a full Gameboy CPU and the SNES is used to show the graphics and sound from the Gameboy. But before the SNES allows an image to be shown, it needs a message from the Gameboy to validate the cartridge. Unfortunately, EZ Flash Jr holds the CPU in reset (basically locks it up) while it’s loading its own firmware. Because of this, the timing is thrown off. The SNES never gets the message and only shows a black screen forever.

But the Gameboy CPU is still running in the background. The SGB Enabler sends the same commands as the Gameboy boot ROM would normally send, and the SNES allows an an image to be shown.

How do you use the SGB Enabler?
Simply copy the included ezgb.dat file to the root of the SD card, overwriting the existing file. Then start the Super Gameboy. (download link at the bottom of the page.) You do not need to touch the reset button on either the cartridge or SNES. It just works.

Does the SGB Enabler restore all SGB functions?
Yes, it enables the game to use colorization and border graphics, and even special sound effects in the few games that use those. And Space Invaders 94’s SNES arcade mode works as well.

Is the SGB Enabler safe to use?
Yes. The SGB Enabler only modifies the kernel (menu), and doesn’t touch the firmware (FPGA). Therefore, you can simply restore it to its original state by copying the original ezgb.dat file from EZ Flash Team onto the SD card, and there’s no risk of bricking. You do not need to upgrade to FW5 (which Team EZ Flash removed). It’s recommended to use FW4.

Can I still use the SGB Enabler on a DMG/GBC?
Yes, the only downside is that the boot time is longer because it always tries to send the commands to wake up the SGB as explained above. I will try to figure out a way to fix this later, but this is just an early beta version to get feedback from users. If this is a problem, simply replace ezgb.dat with the original file from EZ Flash. (Detecting the hardware is not as straightforward as it seems because the EZ Flash Jr has an internal boot ROM that erases the initial registers that programmers normally use to detect which type of hardware the game is running on.)

Does the SGB Enabler work on both PAL and NTSC Super Gameboys?
I only have a PAL SNES, but I’ve region modded it so I can select PAL or NTSC. In my testing, I’ve made sure the SGB Enabler works in both PAL and NTSC mode, but feedback from someone who has a real NTSC SGB would be appreciated.

The SNES reset button doesn’t work!
Please use the reset button on the cartridge, or power cycle the SNES to restart.

My blog post about it (same content as this post) : https://blog.gg8.se/wordpress/2021/08/19/nitro2k01s-sgb-enabler-for-ez-flash-jr/
 

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  • kernel104-sgbenabler.zip
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FAST6191

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No SGB here but very nice to see.

For those wondering what the SGB is and why they might care I quite like this series of articles
https://loveconquersallgam.es/post/2350461718/fuck-the-super-game-boy-introduction
https://loveconquersallgam.es/search/super+game+boy

Equally for my money Bomberman SGB ranks right up there in terms of best classic multiplayer bomberman -- I was never a great fan of the kitchen sink approach of later games so if you are thinking PCE/TG16 (the best of the 16 bit efforts, though the others are no slouch), Saturn or maybe the Bomberman Live thing then I put it up there with those. On the other hand I am also a fan of bother Bomberman 64 and Atomic Bomberman so maybe don't take my word on things here.
 

joyrider3774

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Hey,

Thanks for this i tested it and seems to be working fine, i did notice but i might need to test some more that if you ran a sgb enabled game that changed the colors and you press reset on the ez cartridge that the borders remain, but if you run a normal gameboy game then without sgb support the color (palette) still remains. I don't consider this a real problem thouh as you said we can just power cycle it. For what it's worth i do you your kernal with a beta of the firmware 5 as i need to to make the ez flash work on my "gb boy colour" (the fake gbc clone) but it works fine as far as i can tell in that combination. But i did not test much
 

eastpixel

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Oh yes! You solved my exact problem from today. Can also confirm that it is working.

Hardware: Retron 2HD + Super GameBoy + EZ-FLASH Junior = works. :toot:
 

Es1238623

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Hey! I'm running into some issues with a black screen when trying to use it with my NTSC SNES. Any solutions?
 

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