This is a Atari PBI & ECI Bus extender, for adding expansion board with ease, called Atari Bus EXtender for Atari XE Computers or ABEX for short.
This project expand somehow the Atari 1090XL Bus Expansion in the early 80s but with a simple layout and using only 3.3v compliant electronics. No 5V is available on the bus, and all signals are converted to 3.3v level.
The Bus recall somehow the AteoBus from Amiga 1200 Computers but using a more common nowadays PCI-Express Bus Slots with 64 pins.
Right now there are 2 boards desinged for this bus:
1- Atari DUO Cart (a porting of the famous Uno-Cart Project)
2- Atari MegaRAM (a PortB PIA Emulator) with 1024K RAM memory banked
More boards can be added as soon they do not interfere with the others like using the PBI Protocol device in available in ROM. For example a simple RS232 Board can be designed using a STM32F407 as port EXPANDER with R: handler in internal flash, or a SDCard Hard Drive Simulator can be designed as well.
Even WiFi or Ethernet Controller can be achived flawlessly.
Everything is up to you, using your mind to open the world to this wonderful machine like Atari 130XE.