ABB · AC 800M Controllers ABB PM856AK01 3BSE066490R1 — AC 800M Processor Unit, 24 MHz / 16 MB PM856AK01 is an AC 800M processor unit based on the PM856A CPU, with 24 MHz clock frequency, 16 MB memory and 0.46 ms performance for 1,000 Boolean operations. 01 / Overview AC 800M Processor Unit PM856A CPU with TP830 baseplate and termination hardware. PM856AK01 is the 3BSE066490R1 processor-unit package for the ABB AC 800M controller family. The package includes the PM856A CPU,