the M18 FADAC was an old POS we used in the 1970"s and early 80"s. it was so delicate it spent most of the time in the fixit shop. most FDC's just used long hand, and slide rules.
utill the pockett calculator came out in the early 80's. than we used a programable "texas instruments" sceintific calculator that was a private purchase by the unit. I think the M15 was a predacessor of the FADAC? dont know what thay use now.http://en.wikipedia.org/wiki/Gun_Data_Computer
I was writing this up, and i have a bare bones data sheet on it, but the picture is a photocopy of a photocopy so i cant post it .