Sanni's Open Source Cartridge Reader HW5 Rev5 adds an optional battery for RTC support to the bottom of the main board. I remixed the design to make room for the battery.
Project: https://github.com/sanni/cartreader/
Buy a kit from me here: https://bonzosretro.shop/products/sanni-cart-reader-v5
Buy only the 3D print from me here: https://bonzosretro.shop/products/3d-print-sanni-open-source-cart-reader
The author remixed this model.
Adds space for RTC battery