Caviar 21200 (WDAC21200) Controller Board. Western Digital 585020B PCB, board number WDC 60-600585-002. This is the genuine controller board for a Western Digital Caviar 21200 (WDAC21200) hard drive, managing data read/write operations and drive logic. Ideal for data recovery specialists or for repairing vintage WDAC21200 drives with a matching board failure.Part number: 585020B, PCB# WDC 60-600585-002