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Soniccd123
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A Sega Genesis repro PCB with FeRAM support

by Soniccd123 Fri Jul 31, 2020 1:31 pm

Hello,

I'm a old time reader of racketboy but never posted anything. I've been comunicating with Ziggy587 about his thread http://www.racketboy.com/forum/viewtopic.php?f=56&t=36353, i noticed a lack of cartridge PCBs projects available online for Sega Genesis with save support here and everywhere and also schematics explaining how do they work.

I know that there are ready made PCBs for sale with this purpose but often, for non US residents, they are quite expensive, with PCBs production services being considerably cheaper. Also, this is not a versatile solution considering the needs of each individual

So, with lots of time in my hands thanks to COVID-19, i've decided to build my own cartridge with saving capabilities and make it open and available for the online comunity, thinking about modding possibilities this opens and also to improve my design if needed, as i'm not a engineer, just a amateur who likes electronics.

I also dislike battery backed saves (thats a very personal opinion based on some bad past experiences lol) so i've decided to buid the cart based of non volatile FeRAM. I know this may be not ideal for some people, but as the project is open, this can be easily modified for battery SRAM use.

Finally, here it is: https://github.com/soniccd123/Genesis-FeRAM-Cart

It uses a 27C322 32Mb UV EPROM as the main ROM, a FM1808 256Kb FeRAM for saving and some glue logic. All was designed using KiCAD and can be easily modified for other ROM and RAM types as needed. I've also included a rudimentary DIP switch based bank switching circuit for the possibility of burning multiple files to the ROM. I've already built some units and it works in real hardware with no problems.

I hope this can be useful for someone, i'm open for feedback if any problems arrive and be welcome to make modifications to the board as needed.

Soniccd123

Edit: The gerber files for producing the board are included in the GitHub project.
Last edited by Soniccd123 on Fri Jul 31, 2020 2:46 pm, edited 1 time in total.
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Ziggy587
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Re: A Sega Genesis repro PCB with FeRAM support

by Ziggy587 Fri Jul 31, 2020 1:45 pm

Awesome, thanks so much for sharing this!

I haven't had a chance to look at the schematic yet, but does the dip switches control the ROM and the RAM? Or just the ROM?
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Soniccd123
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Re: A Sega Genesis repro PCB with FeRAM support

by Soniccd123 Fri Jul 31, 2020 2:37 pm

Ziggy587 wrote:Awesome, thanks so much for sharing this!

I haven't had a chance to look at the schematic yet, but does the dip switches control the ROM and the RAM? Or just the ROM?


For now just the ROM, it is possible to control the RAM also, but this needs some thinking, maybe use two DIP switches?
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