Complex sentence: The D-17B is a computer used in missile guidance systems, specifically the Minuteman I NS-1OQ missile guidance system, which contains a D-17B computer, the associated stable platform, and power supplies.
Split into simpler sentences: The D-17B is the computer used the Minuteman I NS-1OQ missile guidance system. The complete guidance system contained a D-17B computer, the associated stable platform, and power supplies.