Military computers
This article specifically addresses US armed forces military computers and their use.
History
Some of the earliest computers were military computers.
Military requirements for portability and ruggedness led to some of the earliest transistorized computers, such as the 1959 AN/MYK-1 (MOBIDIC),
the 1960 M18 FADAC,
and the 1962 D-17B;
the earliest integrated-circuit based computer,
the 1964 D-37C;
as well as one of the earliest laptop computers, the 1982 Grid Compass.
Military requirements for a computer small enough to fit through a submarine's hatch led to the AN/UYK-1.
Construction
Typically a military computer is much more robust than an industrial computer enclosure. There will be more structure inside to support the components, the plug-in cards will be individually supported and secured to assure they do not pop out of their sockets, the processor and heat sink will be secured, memory will be glued into their sockets, and so forth. This is to assure nothing moves during the shock events.