This 1950s to 1970s calculator / computer was used to predict the devastation of nuclear bombs.  It was an Army field instrument for calculating after effects to predict casualties & devastation.  There are two, 2, calculators in original case and 26 page technical directions on use.  Included also is a card with sample calculation examples.    This 1st calculator is titled “Calculator, Nuclear Yield” that measures Yield from Cloud Bottom or Top.  On the backside it reveals answers based upon Fireball in Flash to Bang in seconds to minutes and the blast destruction yield.  The 2nd calculator is titled “Entry – Exit Time After Burst that starts at 1 hour to 10 hours and days to weeks that gives RADS dose rate.  The case is titled “Calculator Set, Radiac and Nuclear Yield: ABC-M28A1.  NSN 6665-00-130-3626.   The obvious calculation results will be “Oh by the way you have a few hours to weeks to live”.  Each calculator is double sided and measures 4.5 inches in diameter and made of celluloid plastic.  It is very bizarre and controversial, but is a piece of our American calculating history when folks were forced into a defensive mode like building underground bomb safes to school drills of hiding under a desk.  The potential of world wide nuclear war is still of concern, but this rarely found calculator is truly an amazing machine to predict the casualties.