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. The D-17B weighs approximately , contains 1,521 transistors, 6,282 diodes, 1,116 capacitors, and 504 resistors. These components are mounted on double copper-clad, engraved, gold-plated, glass fiber laminate circuit boards. There are 75 of these circuit boards and each one has been coated with a flexible polyurethane compound for moisture and vibration protection. The high degree of reliability and ruggedness of the computer are evidenced by the strict requirements of the weapons system. Use of the D-17B is especially appropriate when high reliability is necessary under extreme environment