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Cold War Radar

The SAGE Computer

The SAGE system was composed of different elements and equipment:

Computer:

The AN/FSQ-7 computer was made up of 32 000 different pieces, 60 000 vacuum tubes, 3 000 miles of wire . Each computer had 600 000 resistors, 170 000 diodes and weighed about 275 tons.  It was so large that it occupied the space of a four story-building.

It was able to complete its calculations in mili-seconds.   Like computers today, it used binary numbers which allowed it to work so quickly.  This meant that everything was made up of 2 numbers, 1 and 0 not all the numbers from 0 to 9.  This was not a far stretch because many electronic devices used a binary system, for example, on or off. 

The datar from the radar stations would be sent in groups of pulses which were then given binary numbers.  The computer then converted and displayed this information so that people viewing it could understand.

Memory:

There were three types of memory used by the SAGE computer to store information and data.

Core Memory Storage: Every computer had two types of core memory storage.  The enlarged one could hold 2,228,224 bits of data, and the small core memory storage could hold 139,264 bits.

Drum Memory: This drum memory units could help the core memory when needed.  Most of the time however, it was a secondary memory, used from programs.  It could magnetically record 3,000,000 bits of data, moving at 2, 814 RPMs.

Magnetic Tape Storage: These units held 1,150,000 binary words and gave a back-up to the program needed to run the computer.

Program: 

The program used by SAGE was the Direction Centre Active (DCA).  It was needed to run the computers and had around 88,000 instructions.

Data:

Data came from all three radar lines to SAGE centres to be processed, showing aircraft and their altitude, speed, and destination in 90 seconds.

Radar gave the majority of the data that SAGE used.  Height finders and Long Range Radars (LRRs) were used heavily and Gap Filler Radars (GRF) gave the data from lower altitudes.  The Identification Friend or Foe (IFFs), a piece of equipment located in friendly aircraft, projecting signals to identify itself, also provided information on the nature of the aircraft.