Logic Analyzer, 16 Digital Channels Upgrade, incl. P6616 Probe and Accys, Option for MDO4000C Series Oscilloscopes. The Tektronix MDO4MSO is a permanent upgrade for any model and adds 16 digital channels; contains digital probe P6616 and accessories. The upgrade is activated by an once used application module hardware key, the key is after activation of the function no more necessary.