AN/FST-2 Radar Data Processing SystemTwo bays of the AN/FST-2. The left side of the photo shows the center bay which houses the transfer switch and all the power supplies. The right hand bay houses all the electronics. The electronics bay is duplicated on the other side of the power bay. The AN/FST-2 is a redundant system with two complete and independent systems operating at all times. Each system processes data all the time but only the active system transmits data to the direction center and controls the height finder radar. The neon lamp panel in the center right was used to verify the operation of the system. Each flip-flop had a lamp on both the Q and Qbar output, one for a one, the other for a zero, and both at once if the tube burned out. The memory for this system was a magnetic drum which was synchronized to the radar pulse rate. Data was written on the drum in quarter mile increments. One radar quarter mile was 3.09 microseconds. The two black boxes were PPI (plan position indicators) for the main sweep. There were two more behind the curtain in the "Blue Room", which were used for clutter mapping, where you would literally block the video by drawing on the crt with a black grease pencil.
The AN/FST-2 had approximately 7100 vacuum tubes in three bays of racks, powered by two 400 cycle motor generator sets. The system would process the raw radar data, antenna position information, and IFF data, and transmit it (at 1200 baud, I think) over dedicated phone lines to the SAGE Direction Center, where it was processed and displayed by the AN/FSQ-7 located there.