The Athena Missile Guidance Computer was designed by Seymour Cray at Sperry Rand Corporation. It was designed to guide the silo-launched Titan-1 missile. It cost about $1,800,000 and weighed over 18,000 lbs. It spent most of its operational life in a missile silo.
The computer, when declared surplus by the Federal Government, went to various US universities. The one at Carnegie was used as an undergrad project until 1971, when the former EE undergrad students (Athena Systems Development Group) orchestrated its donation to the Smithsonian. It joined a sister unit, the Atlas Mod I Guidance Computer, at the Smithsonian.
It had a Harvard architecture design; separate data and instruction memories were used.
A Frieden terminal with paper tape equipment was used with the Athena, as well as an operating console. An interesting feature is the mode "battleshort". In this mode, referred to as "melt-before-fail", the power to the machine could NOT be shut off by a failsafe. <[1]
The Athena used a massive motor-generator set with 440 volt 3 phase AC input. I hooked this up from the lab mains, and got the generator set going initially. When the generator was started, the building lights dimmed, and there was no question that the machine was on. The motor generator control unit (seen behind the console) weighed a ton, and the motor/generator itself weighed over 2 tons.
The last launch supported by an Athena computer was a Thor-Agena missile launched in 1972 from Vandenberg AFB in California. It was used on over 400 missile flights. In its operational life, it never launched a missile in anger. The 18 Titan-1 Missile Complexes were only a stop-gap measure (awaiting the Minuteman Missile) and none of the complexes were operational for more than four years.