| rdfs:comment
| - 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
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| abstract
| - 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 environmental conditions such as high shock, acceleration, or vibration that preclude the use of other computers. Since an airborne, computer-controlled missile only gets one chance to execute its mission, the design specifications of the D-17B required very high reliability. This was achieved by using DRL (diode-resistor) logic extensively and only using DTL (diode-transistor) logic where gain or inversion was required in this fully solid-state computer. In the early 1960s when the D-17B was designed, transistors were not as reliable as they are now, thus the designers used transistors only when necessary. The rotating disk memory, with non-destructive readout (NDRO), also enhanced the reliability of the computer. In actual, real-time situations involving Minuteman missiles, the mean time between failures (MTBF) was over 5.5 years.
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