TRANSISTOR MUSEUM™ Historic Transistor Photo Gallery
Transistor Size (1/4” Diameter X 1/4”H) Standard T0-5 Case Date Codes 7111 (1971) and 6741A (1967) Stamped Box ID for TI R212 Polaris Transistors	TEXAS INSTRUMENTS R212 TYPE Germanium PNP Alloy Junction Transistor USAGE Polaris Missile Guidance Computer DATE INTRODUCED Late 1950s CASE STYLES Gold Plated Metal AVAILABILITY Rare (Polaris Program Specific)
HISTORIC NOTES By the mid 1950s, transistor technology had matured to the extent that the military was interested in utilizing these unique devices in “mission-critical” defense programs.  One of the first documented large scale military uses of transistors was the Polaris missile program, which was initiated in 1956 when the Navy began funding a program to develop a ballistic missile that could be launched from a submerged submarine. The inertial guidance computer carried onboard each Polaris missile was developed at the MIT Instrumentation Laboratory, and these first versions used discrete transistor components, such as the R212, while later versions used integrated circuits as this technology became available.  Hundreds of Polaris missiles were produced until 1972, when the Poseidon missile was deployed as a replacement.    Texas Instruments was a major supplier of semiconductors for the Polaris program, beginning with germanium transistors in the 1950s and ICs in the 1960s.  There is a wealth of informative literature documenting the Polaris guidance computer program (and the related Apollo program) authored by Eldon C. Hall, who managed this work at MIT.  (See “Journey to the Moon: The History of the Apollo Guidance Computer”, by Eldon C. Hall, published in 1996 by AIAA).
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