FANUC A20B-8100-0665 is a Main CPU PCB designed for compatible FANUC Series 21i-B CNC systems. It integrates the PMC-SB7 function and Ethernet communication, providing the core processing platform for CNC operation and machine-control tasks. The board is commonly fitted in A02B-0285-Bxxx control-unit configurations and works with compatible CPU processor modules. It is suitable for CNC main-board replacement, maintenance, and repair. All parameters and machining programs should be backed up before replacement and reloaded as required. [stock available]