D37D 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 . They accept and process data and generate steering signals with sufficient accuracy and speed to meet the requirements of the inertial guidance and flight control systems of the Minuteman ICBMs . Computer operation is controlled by an internally stored program which is loaded from a magnetic tape cartridge at the launch facility ( LF ) . Both the D37D computer and the MGC are designed and programmed to control the Minuteman III missile throughout the powered portion of flight . After thrust termination they also control the PBV for the reentry vehicle ( RV ) deployment phase . In addition , they control the alignment of the inertial platform and test / monitor the guidance & control ( G & C ) system and other components to determine continued readiness while missiles are in alert status . The D37D computer began to be replaced by the MGC in 2000 as part of the Guidance Replacement Program ( GRP ) , with fielding planned through 2008 . The MGC incorporates the amplifier assembly functions . When a launch is commanded , a complete retesting of the G & C system is made prior to entering the flight program . During flight , the computer uses missile attitude , change of attitude rate , and velocity signal inputs to solve a series of guidance , steering , and control equations . It also generates missile steering commands and controls staging and thrust termination . Finally , the computer determines whether or not to provide pre - arm signals to the warhead . The pre - arm decision is based on flight safety checks made during powered flight . Missile Guidance Set ( MGS ) . The Autonetics Division of Rockwell International produced all three generations of the Minuteman Missile Guidance Set ( MGS ) . The MGS includes the Gyro Stabilized Platform ( GSP ) , Digital Control Unit ( DCU ) , Missile Guidance Set Control ( MGSC ) and the Amplifier Assembly . The MGS is an inertial guidance system which directs the flight of the missiles . The guidance system operates while the missile is in alert status , thus enabling the missile to be launched in less than one minute . Once the missile is launched , the guidance system cannot be changed or affected from the ground , a feature which prevents enemy interference with the planned trajectory of the missile . During first - stage flight , the computer in the guidance and control ( G & C ) section sends commands to the nozzle control unit ( NCU ) to keep the missile on the precise course required for the reentry vehicles ( RVs ) to reach their designated targets . At the proper instant , the computer sends commands which separate an almost exhausted motor from the missile , and ignites the next stage motor . The G & C section then sends steering commands to the thrust vector control ( TVC ) unit of each succeeding motor stage to keep the rocket on course . The incorporation of current - technology electronics with each generation of the guidance system has resulted in a smaller , more capable , and less vulnerable system . = References =