AVGCART
AVGCART - THE average SD multicart for 8bit Atari
FPGA based multicart for 8bit Atari computers, extensible with SIO and/or ECI/PBI cables
supports CAR (cartridge dump) files up to 1MB and most bankswitching types
supports XEX (executable) files
supports ATR (floppy image) files (read/write) - support is limited without an optional SIO or ECI/PBI cable due to Atari cartridge port constraints (e.g. SW that uses RAM under OS does not work)
This seems to be something strange not related to the AVG cart at all.
The first error message on your picture above pops up from time to time when using/testing SDX. Unfortunately, I could not find the source for it so far.
Running SDX on a 800XL with IDE+ Rev C and 256 KiB Compy Shop memory extension. The files are not found though they even there, as DIR reports.
The other errors show up from time to time as well. It is not predictable when it will happen. But as I saw it sever
