The A8PicoCart is a multi-cart for the Atari 8-bit XL/XE computer.
When plugged into a PC by USB it becomes a Mass Storage device allowing ROM/CAR/XEX & ATR files to be copied to the cartridge. When plugged into an Atari these files are shown on the menu and the device will either emulate the selected cartridge type or act as a XEX file launcher. It also has (very) limited support for ATR.
The A8PicoCart is not intended for use in the Atari 400 or Atari 800 computers.
Manual
https://github.com/robinhedwards/A8PicoCart/blob/main/A8PicoCart%20Manual.pdf
STL Files for 3D printing
https://github.com/robinhedwards/A8PicoCart/tree/main/cartridge%20shell%203d%20print%20files