The D37D Minuteman III flight computer was initially supplied with the LGM-30G missile, as part of the NS-20 navigation system. The NS-20 D37D flight computer is a miniaturized general purpose (serial transmission) digital computer. The new NS-50 missile guidance computer (MGC) is built around a 16-bit high-speed microprocessor chip set. They are both designed to solve real-time positional error problems under the adverse conditions encountered in airborne weapon systems.
Pursuit guidance is a form of guidance widely used in older ground attack missiles. In pursuit guidance, the missile is steered so that the velocity vector of the missile always points at the target. In the early days of guided missiles where the computers were analog this was an easy implementation in the hardware. It found particular use in the early laser-guided bombs with the aerodynamically stabilized birdies on the front of the bomb.
The Sigma 30 is an inertial navigation system produced by SAGEM for use with artillery applications including howitzers, multiple rocket launchers, mortars and light guns. It is currently produced for more than 25 international programs, including France (CAESAR, 2R2M, MLRS), Sweden (FH77 BD, Archer), India,Polish PT-91M tank and the United States (topographic survey). Sigma 30 can also be integrated in more complex systems (Positioning and Azimuth Determination System).