2x PS/2 for keyboard and mouse
1x 6 pin DIN IEC/serial port for 1541 connection etc.
1x USB for power only when NOT plugged in C64.
USB for data (flashing) is on PCB.
As often with Individual products it's not finished and currently 1541 emulation does not support loading a d64, so it's pretty useless even if customers think it's similar to 1541U. Currently, it's not.