"From the manual"
The PRC100 Control Panel is a discrete control panel that provides conventional VTR-type control of Tektronix video disk recorders.
One PRC100 controls up to four video channels using the Profile Protocol over a single RS422 connection. The PRC100 can be used to capture incoming video feeds such as news, commercials, and syndicated shows. Playback of single clips is facilitated by the jog and shuttle functions.
Introduced some time in 1996.