The 3 Axis Parallel Interface board is designed to form the bridge between the PC based control software (EMC) and the X, Y, Z stepper motor drivers. In reality, the board itself is mostly wires. The three stepper motor cables plug in along the right edge, and a standard PC ATX power supply hard drive power plug goes at the bottom.
The six sets of pads in the center of the board are zero ohm resistors. The single resistor in the lower right corner is 100 ohms.