A small PCB buffering the ACSI signals similar to the circuit Atari used in the STE/TT models. Buffer ICs are socketed and can be replaced easily. No DMA IC is included!

 

This PCB is only for 520/1040 STF/STFM (PCB C070789 and C103088). It is not designed to fit into 260ST/520ST and MegaST.

 

You don't need this in STE/TT models!